Showing papers in "Avian Diseases in 2007"
TL;DR: Results from the two HPAI H5N1 viruses from Asia indicate that these viruses did not persist as long as the wild-type AIVs, and that a significant interaction exists between the effects of temperature and salinity on the persistence of AIV.
Abstract: Although fecal-oral transmission of avian influenza viruses (AIV) via contaminated water represents a recognized mechanism for transmission within wild waterfowl populations, little is known about viral persistence in this medium. In order to provide initial data on persistence of H5 and H7 AIVs in water, we evaluated eight wild-type low-pathogenicity H5 and H7 AIVs isolated from species representing the two major influenza reservoirs (Anseriformes and Charadriiformes). In addition, the persistence of two highly pathogenic avian influenza (HPAI) H5N1 viruses from Asia was examined to provide some insight into the potential for these viruses to be transmitted and maintained in the environments of wild bird populations. Viruses were tested at two temperatures (17 C and 28 C) and three salinity levels (0, 15, and 30 parts per thousand sea salt). The wild-type H5 and H7 AIV persistence data to date indicate the following: 1) that H5 and H7 AIVs can persist for extended periods of time in water, with a duration of infectivity comparable to AIVs of other subtypes; 2) that the persistence of H5 and H7 AIVs is inversely proportional to temperature and salinity of water; and 3) that a significant interaction exists between the effects of temperature and salinity on the persistence of AIV, with the effect of salinity more prominent at lower temperatures. Results from the two HPAI H5N1 viruses from Asia indicate that these viruses did not persist as long as the wild-type AIVs.
325 citations
TL;DR: Between December 2003 and January 2004 highly pathogenic avian influenza (HPAI) H5N1 infections of poultry were declared in China, Japan, South Korea, Laos, Thailand, Cambodia, Vietnam, and Indonesia, and an outbreak was reported in Malaysia.
Abstract: Between December 2003 and January 2004 highly pathogenic avian influenza (HPAI) H5N1 infections of poultry were declared in China, Japan, South Korea, Laos, Thailand, Cambodia, Vietnam, and Indonesia. In 2004 an outbreak was reported in Malaysia. In 2005 H5N1 outbreaks were recorded in poultry in Russia, Kazakhstan, Mongolia, Romania, Turkey, and Ukraine, and virus was isolated from swans in Croatia. In 2004 HPAI H5N1 virus was isolated from smuggled eagles detected at the Brussels Airport and in 2005 imported caged birds held in quarantine in England. In 2006 HPAI was reported in poultry in Iraq, India, Azerbaijan, Pakistan, Myanmar, Afghanistan, and Israel in Asia; Albania, France, and Sweden in Europe; and Nigeria, Cameroon, and Niger in Africa; as well as in wild birds in some 24 countries across Asia and Europe. In 2003, over 25,000,000 birds were slaughtered because of 241 outbreaks of HPAI caused by virus of H7N7 subtype in the Netherlands. The virus spread into Belgium (eight outbreaks) a...
251 citations
TL;DR: The Asian H5N1 HPAI viruses have changed from producing inconsistent respiratory infections in 2-wk-old domestic ducks to some strains being highly lethal in ducks with virus in multiple internal organs and brain, unlike these viruses in gallinaceous poultry, which are highly lethal irrespective of the host age.
Abstract: Avian influenza (AI) viruses are a diverse group of viruses that can be divided into 144 subtypes, based on different combinations of the 16 hemagglutinin and nine neuraminidase subtypes, and two pathotypes (low and high pathogenicity [HP]), based on lethality for the major poultry species, the chicken. However, other criteria are important in understanding the complex biology of AI viruses, including host adaptation, transmissibility, infectivity, tissue tropism, and lesion, and disease production. Overall, such pathobiological features vary with host species and virus strain. Experimentally, HPAI viruses typically produce a similar severe, systemic disease with high mortality in chickens and other gallinaceous birds. However, these same viruses usually produce no clinical signs of infection or only mild disease in domestic ducks and wild birds. Over the past decade, the emergent HPAI viruses have shifted to increased virulence for chickens as evident by shorter mean death times and a greater propensity for massive disseminated replication in vascular endothelial cells. Importantly, the Asian H5N1 HPAI viruses have changed from producing inconsistent respiratory infections in 2-wk-old domestic ducks to some strains being highly lethal in ducks with virus in multiple internal organs and brain. However, the high lethality for ducks is inversely related to age, unlike these viruses in gallinaceous poultry, which are highly lethal irrespective of the host age. The most recent Asian H5N1 HPAI viruses have infected some wild birds, producing systemic infections and death. Across all bird species, the ability to produce severe disease and death is associated with high virus replication titers in the host, especially in specific tissues such as brain and heart.
190 citations
TL;DR: H5 Eurasian RRT-PCR was invaluable in H5 outbreak diagnosis and management by virtue of its rapidity and high degree of sensitivity and specificity and provides a platform for automation that can be applied for large-scale intensive investigations, including surveillance.
Abstract: Real time reverse transcriptase (RRT)–polymerase chain reaction (PCR) for the detection of Eurasian H5 avian influenza virus (AIV) isolates was adapted from an existing protocol, optimized, and validated using a number of genetically diverse H5 isolates (n = 51). These included 34 “Asian lineage” H5N1 highly pathogenic avian influenza (HPAI) viruses (2004–2006), plus 12 other H5 isolates from poultry outbreaks and wild birds in the Eastern Hemisphere (1996–2005). All 51 were positive by H5 Eurasian RRT-PCR. Specificity was assessed by testing representative isolates from all other AI virus subtypes (n = 52), non-AI avian pathogens (n = 8), plus a negative population of clinical specimens derived from AI-uninfected wild birds and poultry (n = 604); all were negative by H5 Eurasian RRT-PCR. RNA was directly extracted from suspect HPAI H5N1 clinical specimens (Africa, Asia, and Europe; 2005–2006; n = 58) from dead poultry and wild birds, and 55 recorded as positive by H5 Eurasian RRT-PCR: Fifty-one ...
175 citations
TL;DR: The observed differences in pathology between ducks infected at different ages is unclear and may be associated with a variety of factors including the virus strain, host immune response, host cell maturation, and capacity to support viral replication.
Abstract: Ducks and other wild aquatic birds are the natural reservoir of type A influenza viruses, which normally are nonpathogenic in these birds. However, the Asian highly pathogenic avian influenza (HPAI) viruses have evolved from producing no disease or mild respiratory infections in ducks to some strains producing severe systemic disease and mortality. To further understand the pathogenicity of these strains in ducks, we studied the gross and histologic lesions and tissue distribution of viral antigen in 2- and 5-wk-old white Pekin ducks infected with different Asian-origin H5N1 AI viruses. Seven of eight 2-wk-old ducks inoculated with A/Egret/HK/757.2/02 developed acute disease, including severe neurological dysfunction and death. However, this virus killed only two of eight 5-wk-old ducks. Two additional viruses, A/Vietnam/1203/04 and A/Crow/Thailand/04, also produced high mortality in 2-wk-old ducks. Microscopic lesions and AI viral antigen were observed most frequently in the nasal cavity, brain, heart, adrenal glands, and pancreas. Another virus, A/Thailand PB/6231/04, killed three of eight 2-wk-old ducks but did not induce neurological signs. Furthermore, older ducks infected with this virus did not present clinical signs or gross lesions, and their tissues showed very few microscopic lesions. All the viruses studied established systemic infections in both younger and older ducks, with viral replication in tissues correlating with the severity of the clinical signs. The differences in mortality induced by HPAI H5N1 viruses in ducks are reflected in the pathological findings and antigen distribution in tissues. However, the observed differences in pathology between ducks infected at different ages is unclear and may be associated with a variety of factors including the virus strain, host immune response, host cell maturation, and capacity to support viral replication.
131 citations
TL;DR: A comprehensive quality assurance strategy, encompassing both broadly based risk-reduction practices and targeted testing to detect pathogens of concern, has been associated with a lower incidence of Salmonella Enteritidis infections in both egg-laying flocks and humans in a number of countries.
Abstract: Of more than 2500 identified Salmonella serotypes, only a small proportion are common in poultry flocks. However, there is an epidemiologically important connection between poultry products and human infections because many of the serotypes that are most prevalent in humans (such as Salmonella Typhimurium and Salmonella Enteritidis) are similarly common in poultry. The scope of food safety efforts for poultry products has been broadened in recent years to include more attention to animal production (or preharvest) issues. The goal of preharvest poultry food safety is to minimize opportunities for the introduction, persistence, and transmission of flock infections with Salmonella and other human pathogens. This objective can be pursued either by general strategies directed against all Salmonella serotypes (and in some instances against other pathogenic microorganisms as well) or by more specific strategies that are designed to act with precision against particular Salmonella serotypes with distinctive public health or economic significance. Risk assessment studies have recommended intervention at multiple steps in the farm-to-table continuum as the most productive overall approach. A comprehensive quality assurance strategy, encompassing both broadly based risk-reduction practices and targeted testing to detect pathogens of concern, has been associated with a lower incidence of Salmonella Enteritidis infections in both egg-laying flocks and humans in a number of countries. Although the emphasis in these types of programs is primarily on risk reduction, testing provides essential verification of the efficacy and cost-effectiveness of risk-reduction practices (and identifies flocks infected with uniquely problematic serotypes). Vaccination can enhance the short-term responsiveness of control programs to address problems involving specific serotypes of elevated significance.
127 citations
TL;DR: It is recognized that the number of clinical cases does not truly reflect the levels of infection, and countries should adopt integrated control programs using the combination of measures best suited to the local environment.
Abstract: Numerous lessons have been learned so far in controlling H5N1 avian influenza in Asia. Early detection of incursions of virus prevented establishment of the disease in several countries, notably Japan, South Korea, and Malaysia. In countries where detection of early cases was delayed, infection is endemic and has been for three or more years. Control measures implemented in these countries need to reflect this finding. Vaccination will continue to be one of the key measures used in these endemically infected countries. Used alone, vaccination will not result in elimination of H5N1 viruses from a country, but, if used correctly, it will markedly reduce the prevalence of and susceptibility to infection. Vaccination has already played a valuable role in reducing the adverse effects of H5N1 viruses. Mass culling also reduces the level of infection in infected areas. However, the long-term benefits are limited in endemically infected countries owing to the high probability of reinfection on restocking unless other measures are used in parallel. Full epidemiological studies have not been conducted in many infected countries. Nevertheless, it is recognized that the number of clinical cases does not truly reflect the levels of infection. Domestic ducks and large live poultry markets have played a key role in the persistence of infection, because they can be infected silently. In tackling this disease, countries should adopt integrated control programs using the combination of measures best suited to the local environment. All surveillance data should be shared, both positive and negative, and should include information on cases of infection and disease. Socioeconomic and ecological implications of all control measures should be assessed before implementation, especially the impact on the rural poor.
123 citations
TL;DR: Although the ability of these Salmonella isolates to colonize different regions of the reproductive tract in laying hens was reflected in deposition in both yolk and albumen, there was no indication that any specific affinity of individual isolates for particular regions of this tract produced distinctive patterns of deposition in eggs.
Abstract: Internal contamination of eggs by Salmonella Enteritidis has been a significant source of human illness for several decades and is the focus of a recently proposed U.S. Food and Drug Administration regulatory plan. Salmonella Heidelberg has also been identified as an egg-transmitted human pathogen. The deposition of Salmonella strains inside eggs is apparently a consequence of reproductive tissue colonization in infected laying hens, but the relationship between colonization of specific regions of the reproductive tract and deposition in different locations within eggs is not well documented. In the present study, groups of laying hens were experimentally infected with large oral doses of Salmonella Heidelberg, Salmonella Enteritidis phage type 13a, or Salmonella Enteritidis phage type 14b. For all of these isolates, the overall frequency of ovarian colonization (34.0%) was significantly higher than the frequency of recovery from either the upper (22.9%) or lower (18.1%) regions of the oviduct. No significant differences were observed between the frequencies of Salmonella isolation from egg yolk and albumen (4.0% and 3.3%, respectively). Some significant differences between Salmonella isolates were observed in the frequency of recovery from eggs, but not in the frequency or patterns of recovery from reproductive organs. Accordingly, although the ability of these Salmonella isolates to colonize different regions of the reproductive tract in laying hens was reflected in deposition in both yolk and albumen, there was no indication that any specific affinity of individual isolates for particular regions of this tract produced distinctive patterns of deposition in eggs.
122 citations
TL;DR: This study has contributed to the harmonization of AI PCR protocols in EU laboratories and influenced AI laboratory contingency planning following the first European reports of H5N1 highly pathogenic AI during autumn 2005.
Abstract: Many different polymerase chain reaction (PCR) protocols have been used for detection and characterization of avian influenza (AI) virus isolates, mainly in research settings. Blind ring trials were conducted to determine the most sensitive and specific AI PCR protocols from a group of six European Union (EU) laboratories. In part 1 of the ring trial the laboratories used their own methods to test a panel of 10 reconstituted anonymized clinical specimens, and the best methods were selected as recommended protocols for part 2, in which 16 RNA specimens were tested. Both panels contained H5, H7, other AI subtypes, and non-AI avian pathogens. Outcomes included verification of 1) generic AI identification by highly sensitive and specific M-gene real-time PCR, and 2) conventional PCRs that were effective for detection and identification of H5 and H7 viruses. The latter included virus pathotyping by amplicon sequencing. The use of recommended protocols resulted in improved results among all six laboratories in part 2, reflecting increased sensitivity and specificity. This included improved H5/H7 identification and pathotyping observed among all laboratories in part 2. Details of these PCR methods are provided. In summary, this study has contributed to the harmonization of AI PCR protocols in EU laboratories and influenced AI laboratory contingency planning following the first European reports of H5N1 highly pathogenic AI during autumn 2005.
119 citations
TL;DR: The need for more ornithologic input into epidemiological studies of HPAI H5N1 is highlighted as there is only limited evidence that some wild birds can carry the virus asymptomatically, and no evidence from wild bird outbreaks that they have done so over long distances on seasonal migration routes.
Abstract: There is much debate about the relative roles of poultry movements and wild bird movements in the spread of highly pathogenic avian influenza H5N1. This article looks at the problem from an ornithologic perspective. Outbreaks in wild birds are examined in relation to three scenarios of possible wild bird involvement in virus transmission. These scenarios are examined separately for five phases of the outbreak that began in 1997 and which has recently become more dynamic in terms of virus spread. Most outbreaks in wild birds seem to reflect local acquisition of infection from a contaminated source, followed by rapid death nearby. Outbreaks in Europe in early 2006 indicate that the virus can be spread further by wild birds and thus that they can become infected and travel varying distances before dying, and probably passing the infection to other wild birds before death. There is only limited evidence that some wild birds can carry the virus asymptomatically, and no evidence from wild bird outbreaks that they have done so over long distances on seasonal migration routes. Other potential sources of infection and evidence for asymptomatic infection in wild birds are discussed, and the need for more ornithologic input into epidemiological studies of HPAI H5N1 is highlighted.
111 citations
TL;DR: Comparison of infected birds with one group of turkeys that were negative for enteric viruses by the methods used here suggests that astrovirus and/or rotavirus may affect production, and the full impact on flock performance needs to be further determined.
Abstract: A longitudinal survey to detect enteric viruses in intestinal contents collected from turkeys in eight commercial operations and one research facility was performed using molecular detection methods. Intestinal contents were collected from turkeys prior to placement, with each flock resampled at 2, 4, 6, 8, 10, and 12 wk of age. The samples were screened for astrovirus, rotavirus, reovirus, and turkey coronavirus (TCoV) by a reverse transcriptase and polymerase chain reaction (RT-PCR), and for groups 1 and 2 adenovirus by PCR. Rotavirus was the only virus detected prior to placement (7 of 16 samples examined). All of the commercial flocks were positive for rotavirus and astrovirus from 2 until 6 wk of age, and most were intermittently positive until 12 wk of age, when the birds were processed. Of the 96 samples collected from birds on the farms, 89.5% were positive for astrovirus, and 67.7% were positive for rotavirus. All flocks were negative for TCoV, reovirus, and group 1 adenovirus at all time points, and positive for group 2 adenovirus (hemorrhagic enteritis virus) at 6 wk of age. All the flocks monitored were considered healthy or normal by field personnel. Turkeys placed on research facilities that had been empty for months and thoroughly cleaned had higher body weights and lower feed conversion rates at 5 wk of age when compared to turkeys placed on commercial farms. Intestinal samples collected at 1, 2, and 3 wk of age from these turkeys were free of enteric viruses. This report demonstrates that astroviruses and rotaviruses may be present within a turkey flock through the life of the flock. Comparison of infected birds with one group of turkeys that were negative for enteric viruses by the methods used here suggests that astrovirus and/or rotavirus may affect production. The full impact on flock performance needs to be further determined.
TL;DR: The development of a multiplex reverse transcriptase–polymerase chain reaction (RT-PCR) assay specific for astroviruses and avian rotavirus in turkey-origin and chicken-origin samples is detailed.
Abstract: Recent studies have revealed the presence of astroviruses and rotavirus in numerous poorly performing and healthy chicken and turkey flocks in the United States. The phylogenetic analysis of the sequence data produced during these studies has identified four groups of avian astroviruses circulating in the United States: turkey astrovirus types 1 and 2 (TAstV-1 and TAstV-2), avian nephritis virus (ANV), and a chicken-origin astrovirus (CAstV). As the molecular epidemiology of poultry enteric disease is poorly understood, the development of updated diagnostic assays is crucial to the continued surveillance and management of enteric disease in affected as well as healthy flocks. This report details the development of a multiplex reverse transcriptase–polymerase chain reaction (RT-PCR) assay specific for astroviruses and avian rotavirus in turkey-origin and chicken-origin samples. The assay consists of two multiplex tests, one for turkey-origin samples and one for chicken-origin samples. The turkey s...
TL;DR: Molecular diagnostic tests recently have proven themselves to be invaluable in controlling disease outbreaks around the world and the development of internal controls, robotics, and bead reagents are providing improved performance of existing tests, and new technologies will likely provide better tests for the future.
Abstract: Molecular diagnostic tests are commonly used to diagnose avian influenza virus because they are sensitive and can be performed rapidly, with high throughput, and at a moderate cost. Molecular diagnostic tests recently have proven themselves to be invaluable in controlling disease outbreaks around the world. Several different methods, including traditional reverse transcription-polymerase chain reaction (PCR), real-time reverse transcription-polymerase chain reaction, and nucleic acid sequence-based amplification among others, have been described for the diagnosis of avian influenza in poultry with many different variations of primers, probes, enzymes, etc. Few of these tests have been validated, with the understanding that validation should be described as a level of comparison testing to show "fitness for purpose." None of the molecular diagnostic tests are validated for all species or specimen types that might be presented to a diagnostic laboratory. The sensitivity and specificity for all the molecular tests are governed by three critical control points, including RNA extraction, enzymes used for amplification, and the sequence of primers and probes. The RNA extraction step is of particular concern, since high-quality RNA is needed for any of the molecular tests. Some sample types, including cloacal (fecal) swabs and tissues, are difficult to process, with issues of poor RNA extraction or PCR inhibitors being common. The development of internal controls, robotics, and bead reagents are providing improved performance of existing tests, and new technologies will likely provide better tests for the future. With any molecular test, assay assurance must be performed on an ongoing basis, which includes the use of proficiency panels to measure test performance.
TL;DR: Each country reported isolations of H5N2 virus from poultry and the large-scale use of inactivated and recombinant H5 vaccines in their AI control programs and in Colombia, AI was reported for the first time when antibodies to H9N2 were detected in chickens by routine surveillance.
Abstract: Between 2002 and 2005, three outbreaks of highly pathogenic avian influenza (HPAI) occurred in the Americas: one outbreak in Chile (H7N3) in 2002, one outbreak in the United States (H5N2) in 2004, and one outbreak in Canada (H7N3) in 2004. The outbreak in Chile was limited to a large broiler breeder operation and a nearby turkey flock and represented the first outbreak of HPAI in that country. The outbreak of HPAI in the United States occurred in Texas and was limited to one premise where chickens were raised for sale in nearby live-bird markets. The outbreak in Canada was the largest of the three HPAI outbreaks, involving 42 premises and approximately 17 million birds in the Fraser Valley, British Columbia. In each of the HPAI outbreaks, the disease was successfully eradicated by depopulation of infected farms. All other reports of infections in poultry and isolations from wild bird species pertained to low pathogenicity avian influenza (LPAI) viruses. Animal Health Officials in Canada reported ...
TL;DR: Outbreaks of H5N1 highly pathogenic avian influenza (HPAI) occurred in various types of domestic poultry in Thailand during 2004–05, causing serious socioeconomic consequences to the poultry industry, the social community, farmers' livelihood, and human health.
Abstract: Outbreaks of H5N1 highly pathogenic avian influenza (HPAI) occurred in various types of domestic poultry in Thailand during 2004-05. H5N1 viruses were also detected in humans and other mammalian species. Infections were mainly detected in backyard chickens and domestic ducks. The geographic distribution of the 2004 outbreaks was widespread throughout Thailand; most outbreaks occurred in the Central Region, the southern part of the Northern Region, and the Eastern Region. In 2005, the H5N1 outbreaks continued and showed a clustered pattern in four provinces in the southern part of the Northern Region and in one province in the Central Region. H5N1 HPAI outbreaks caused serious socioeconomic consequences to the poultry industry, the social community, farmers' livelihood, and human health. After key measures were implemented, the incidence of the outbreaks declined remarkably in 2005.
TL;DR: Similar measures undertaken to control H9N2 outbreaks have not been successful in the affected areas, with continuing increased mortality and heavy production losses in broilers and layers, respectively, and a similar strategy has been devised to combat the spread of newly introduced H5N1 HPAIV.
Abstract: From November 2003 to June 2004 an epidemic of high pathogenicity avian influenza (HPAI) virus of subtype H7N3 affected the major layer and broiler-breeder raising areas of the country. This was accompanied by an outbreak of low pathogenicity avian influenza (LPAI) virus of type H9N2 in broilers and layers, which continued during 2005. Subsequently, in February 2006 avian influenza virus (AIV) subtype H5N1 was for the first time found in two isolated commercial flocks in this country. The HPAI outbreak of 2003–2004 was eventually overcome by enforcing biosecurity measures, controlling poultry movements, using inactivated vaccines, and introducing a comprehensive AI surveillance network throughout the country. However, similar measures undertaken to control H9N2 outbreaks have not been successful in the affected areas, with continuing increased mortality and heavy production losses in broilers and layers, respectively. A similar strategy has been devised to combat the spread of newly introduced H5...
TL;DR: The CEO vaccine replicated faster and reached higher viral genome copy number than the TCO vaccine in the conjunctiva and trachea of eye drop–inoculated and contact-exposed birds, attaining peaks of viral DNA as elevated as those observed in inoculated birds.
Abstract: The aim of this study was to evaluate the replication of live attenuated infectious laryngotracheitis virus vaccines in selected tissues and their ability to transmit to contact-exposed birds. Four-week-old specific-pathogen-free chickens were eye drop-inoculated with tissue culture origin (TCO) and chicken embryo origin (CEO) vaccines. Contact-exposed chickens were housed in direct contact with eye drop-inoculated chickens from the first day postinoculation. Virus isolation and real-time polymerase chain reaction were used to detect the presence of live virus and viral DNA, respectively, in the trachea, trigeminal ganglia, eye conjunctiva, cecal tonsils, and cloaca from eye drop-inoculated and contact-exposed birds at days 2, 4, 5 to 10, 14, 18, 21, 24, and 28 postinoculation. No differences were observed in the ability of the TCO and CEO vaccines to replicate in the examined tissues. Both vaccines presented a localized replication in the eye conjunctiva and the trachea. Both vaccines were capable of transmitting to contact-exposed birds, attaining peaks of viral DNA as elevated as those observed in inoculated birds. The CEO vaccine replicated faster and reached higher viral genome copy number than the TCO vaccine in the conjunctiva and trachea of eye drop-inoculated and contact-exposed birds. The viral DNA from both vaccines migrated to the trigeminal ganglia during early stages of infection. Although the CEO and TCO vaccines were not recovered from the cecal tonsils and the cloaca, low levels of viral DNA were detected at these sites during the peak of viral replication in the upper respiratory tract.
TL;DR: The results confirm the excellent level of protection induced by rFP-AIV-H5 in SPF chickens against two recent Asian HPAI H5N1 isolates.
Abstract: A recombinant fowlpox-avian influenza (AI) H5 vaccine (rFP-AIV-H5) expressing the hemagglutinin of the A/turkey/Ireland/1378/83 H5N8 AI isolate has been used in Central America since 1998 to control H5N2 low pathogenicity AI. Previously, this vaccine was shown to induce full protection against a panel of H5 highly pathogenic (HP) AI isolates, including HPAI H5N1. Here, we evaluate the efficacy of rFP-AIV-H5 against escalating doses of HPAI H5N1 A/chicken/SouthKorea/ES/03 isolate and against the HPAI H5N1 A/chicken/Vietnam/0008/2004 isolate. In both studies, 1-day-old specific pathogen-free (SPF) chickens were vaccinated by subcutaneous route with rFP-AIV-H5 and challenged 3 wk later by the oronasal route. In the first study, full protection was observed up to a challenge dose of 6.5 log10 embryo infectious dose (EID50), and the 50% chicken infectious dose was estimated to be 3.1 and 8.5 log10 EID50 in the control and the rFP-AIV-H5-vaccinated group, respectively. A 2–4 log10 and >4 log10 reductio...
TL;DR: Results indicate that HS plays a role as an attachment factor for IBV, working in concert with other factors like sialic acid to mediate virus binding to cells, and may explain in part the extended tropism of IBV Beaudette.
Abstract: The avian coronavirus infectious bronchitis virus (IBV) strain Beaudette is an embryo-adapted virus that has extended species tropism in cell culture. In order to understand the acquired tropism of the Beaudette strain, we compared the S protein sequences of several IBV strains. The Beaudette strain was found to contain a putative heparan sulfate (HS)-binding site, indicating that the Beaudette virus may use HS as a selective receptor. To ascertain the requirements of cell-surface HS for Beaudette infectivity, we assayed for infectivity in the presence of soluble heparin as a competitor and determined infectivity in mutant cell lines with no HS or glycosaminoglycan expression. Our results indicate that HS plays a role as an attachment factor for IBV, working in concert with other factors like sialic acid to mediate virus binding to cells, and may explain in part the extended tropism of IBV Beaudette.
TL;DR: The results suggest that a test model including vaccination of chickens at 3wk, bleeding at 6 wk, and quantitative assessment of serologic response by using a standardized hemagglutination inhibition assay system can be an excellent predictor of vaccine efficacy.
Abstract: A study was conducted to evaluate efficacy of inactivated, reverse genetics-based H5N3 avian influenza vaccines and the predictive ability of a vaccination/serology model for testing vaccine batches. Serologic response, protection against mortality, and protection against viral shedding from trachea and cloaca were assessed for vaccines prepared varying only in antigen content. When the birds were grouped according to serologic response, a clear association with protection could be seen. In general, for birds possessing a nonmeasurable titer (<10), mortality after challenge was a near certainty. Low titers of 10 to 40 resulted in the prevention of mortality but not viral shedding. Titers greater than 40 prevented mortality and reduced viral shedding. The results suggest that a test model including vaccination of chickens at 3 wk, bleeding at 6 wk, and quantitative assessment of serologic response by using a standardized hemagglutination inhibition assay system can be an excellent predictor of vac...
TL;DR: TaqMan reverse transcriptase-polymerase chain reaction assays for rapid detection of all AI viruses (influenza type A) and for identification of H5N1 of the Eurasian lineage allow definitive confirmation of an AI virus as H5 within hours, which is crucial for rapid implementation of control measures in the event of an outbreak.
Abstract: Highly pathogenic avian influenza (AI) H5N1 viruses have been spreading from Asia since late 2003. Early detection and classification are paramount for control of the disease because these viruses are lethal to birds and have caused fatalities in humans. Here, we described TaqMan reverse transcriptase-polymerase chain reaction assays for rapid detection of all AI viruses (influenza type A) and for identification of H5N1 of the Eurasian lineage. The assays were sensitive and quantitative over a 105–106 linear range, detected all of the tested AI viruses, and enabled differentiation between H5 and H7 subtypes. These tests allow definitive confirmation of an AI virus as H5 within hours, which is crucial for rapid implementation of control measures in the event of an outbreak.
TL;DR: This study collected the first Salmonella prevalence and antimicrobial resistance data on pasture poultry farms and found that flocks reared conventionally had higher prevalence than in pasture, and pasture isolates found to have resistance were from the Southeast.
Abstract: The objective of this study was to compare Salmonella prevalence and antimicrobial resistance between pasture and conventional poultry farms. We collected the first Salmonella prevalence and antimicrobial resistance data on pasture poultry farms. Fecal droppings were collected from 31 farms from Wisconsin (nine farms from each production type) and the Southeast (North Carolina, Virginia, and South Carolina; five conventional and 10 pasture poultry farms) in a 1-yr period. The specimens were cultured for Salmonella and tested for resistance to 12 antimicrobials. A univariate analysis was conducted to determine the significant differences in prevalence and resistance. At the farm level, no significant difference in Salmonella prevalence was found on 33% pasture and 47% conventional poultry farms (P = 0.4928). On an individual specimen level, flocks reared conventionally had higher prevalence than in pasture (P < 0.0001). Of all the isolates found to have resistance, 80% were from the Southeast. Of ...
TL;DR: Genetic analysis indicates independent, spontaneous mutations in fljB in at least four distinct Salmonella Typhimurium strains of animal origin circulating in nature, identifying four “distinct” strains.
Abstract: Although Salmonella remains one of the leading causes of foodborne illnesses in the United States, the Salmonella enterica serovars and genetic types associated with most infections appear to fluctuate over time. Recently, the Center for Disease Control and Prevention (CDC) has reported an increase in cases of salmonellosis caused by Salmonella 4,[5],12:i:−. Similarly, this unusual Salmonella serovar has been isolated from cattle and poultry in the state of Georgia. We examined the genetic relatedness of Salmonella 4,[5],12:i:−, isolated from several different poultry companies and dairy farms in Georgia, by pulsed-field gel electrophoresis (PFGE). Several Salmonella 4,[5],12:i:− isolates had PFGE patterns identical or similar to PFGE patterns of Salmonella Typhimurium isolated from numerous animal sources. We identified distinct PFGE patterns for Salmonella 4,[5],12:i:− and matching Salmonella Typhimurium PFGE patterns, identifying four “distinct” strains. We focused a more specific analysis on ...
TL;DR: An overview of the changing properties that have been observed during the current H5N1 outbreaks is provided.
Abstract: The H5N1 virus currently circulating is continuing to evolve, and it has already resulted in the extension of its host and geographical range. It is likely that H5N1 will become a global problem for the poultry industry. How many of the recent H5N1 changes observed have been induced by changing patterns in poultry raising? A change in attitude on the use of high-quality vaccines is a change that would drastically help in the control of the current epidemic in the poultry industry. This article provides an overview of the changing properties that have been observed during the current H5N1 outbreaks.
TL;DR: Examination of contact and airborne transmission of the H5N1 virus to chickens in a negative-pressure isolator using various numbers of infected chickens and separate compartments found that the contact transmission did occur inefficiently when one or two chickens were infected, whereas the transmission was efficient when four poultry were infected.
Abstract: Typically highly pathogenic avian influenza (HPAI) viruses spread very rapidly among chickens within sheds. However, the spread was slower than expected for the initial 10 days of the index farm in Japan during 2004. This slow spread, as well as the lack of gross lesions, clinical signs, or high mortality, hindered the field veterinarian from reporting a suspected HPAI outbreak to the veterinary office. To understand the field conditions for the slow virus spread, we examined contact and airborne transmission of the H5N1 virus to chickens in a negative-pressure isolator using various numbers of infected chickens and separate compartments. We found that the contact transmission did occur inefficiently when one or two chickens were infected, whereas the transmission was efficient when four chickens were infected. Airborne transmission of the HPAI virus was also dependent on the number of infected chickens and was less efficient than contact transmission. These data together with field observations suggested that number of infected chickens, chicken house types, and amount of environmental contamination might affect the virus transmission efficiency to chickens.
TL;DR: The use of gallinacin single-nucleotide polymorphisms as molecular markers for genetic selection for Salmonella Enteritidis resistance might result in reduced bacterial burden via development of an enhanced innate immune response.
Abstract: Salmonella enterica serovar Enteritidis is a gram-negative bacterium that negatively affects human and animal health. Many eukaryotes use antimicrobial peptides (α-defensins, β-defensins, γ-defensins, and cathelicidins) in innate immune responses to fight bacterial infections. Poultry gallinacins are the functional equivalents of mammalian β-defensins. Two related advanced intercross lines of chickens were analyzed for association of gallinacin genotypic variation with Salmonella Enteritidis burden levels in the cecum and spleen after infection. Thirteen genes of the chicken β-defensin cluster (GAL1–13) were sequenced from individuals of each advanced intercross line, plus the founder broiler sire and representatives of the highly inbred Leghorn and Fayoumi founder dam lines. The mean was 17 single-nucleotide polymorphisms (SNPs) per kilobase. One single-nucleotide polymorphism per gene was genotyped with SNaPshot to test for statistical associations with Salmonella Enteritidis colonization after...
TL;DR: In this article, a set of primers were designed to detect and amplify viruses from each of the six ALV subgroups: A, B, C, D, E, and J. The results showed that the contaminant was a subgroup A ALV.
Abstract: Avian leukosis viruses (ALVs) are common in many poultry flocks and can be detected using an enzyme-linked immunosorbent assay or any other test designed to identify p27, the group-specific antigen located in gag. However, endogenous retroviruses expressing p27 are often present and can be confused with exogenous ALVs. A more specific and informative assay involves targeting the variable envelope glycoprotein gene (gp85) that is the basis for dividing ALVs into their different subgroups. We designed polymerase chain reaction (PCR) primers that would specifically detect and amplify viruses from each of the six ALV subgroups: A, B, C, D, E, and J. Subgroup B and D envelopes are related, and our B-specific primers also amplified subgroup D viruses. We also designed a set of common primers to amplify any ALV subgroup virus. To demonstrate the usefulness of these primers, we obtained from the Center for Veterinary Biologics in Iowa culture supernatant from chicken embryo fibroblasts infected with an ALV that was found to be a contaminant in two commercial Marek's disease vaccines. Using our PCR primers, we demonstrate that the contaminant was a subgroup A ALV. We cloned and sequenced a portion of the envelope gene and confirmed that the ALV was a subgroup A virus. Unlike typical subgroup A viruses, the contaminant ALV grew very slowly in cell culture. We also cloned and sequenced a portion of the long terminal repeat (LTR) from the contaminant virus. The LTR was found to be similar to those LTRs found in endogenous ALVs (subgroup E) and very dissimilar to LTRs normally found in subgroup A viruses. The E-like LTR probably explains why the contaminant grew so poorly in cell culture.
TL;DR: Serogroups O, serotypes K1 and K5, and genes cvaC, iss, iutA, papA, tsh, and usp, which have been thought to be related to virulence, were examined for their association with E. coli strains isolated from diseased and healthy chickens.
Abstract: The virulence factors of avian pathogenic Escherichia coli (APEC) isolated in Japan were investigated. Serogroups O, serotypes K1 and K5, and genes cvaC, iss, iutA, papA, tsh, and usp, which have been thought to be related to virulence, were examined for their association with E. coli strains isolated from diseased and healthy chickens. The frequently recognized serogroups O1, O2, and O78 were found in 56 of 125 (44.8%) strains of diseased chickens (APEC) versus 13 of 100 (13.0%) strains of healthy chickens (commensal E. coli), a significant difference at risk ratio < 0.01. Although iss, iutA, and tsh were widely distributed in the APEC irrespective of O serogroup, papA, usp, and the K1 serotype were detected in serogroup O2 of APEC. The kfiD gene related to the K5 capsule and VT, LT, and ST genes related to exotoxins were not detected in any strains examined.
TL;DR: A universal avian endogenous internal control (bird β-actin) is developed and applied to influenza A diagnosis and proves an excellent strategy both for avoiding false negative diagnostic results and for standardizing virus quantification studies.
Abstract: Real-time reverse transcriptase–polymerase chain reaction (RRT-PCR) is becoming an established first-line diagnostic assay as well as a precise quantification tool for avian influenza virus detection. However, there remain some limitations. First, we show that the sensitivity of RRT-PCR influenza detection can be 10- to 100-fold inhibited in oropharyngeal and cloacal swabs. Adding 0.5 U of heat-activated Taq DNA polymerase successfully reverses PCR inhibition. Second, an excellent strategy for detecting false negative samples is the coamplification of an internal control from each sample. We developed a universal avian endogenous internal control (bird β-actin) and apply it to influenza A diagnosis. Moreover, this internal control proves useful as a normalizer control for virus quantification, because β-actin gene expression does not change in infected vs. uninfected ducks. A combined panel of wild bird cloacal swabs, wild bird tissue samples, experimental duck swabs, and experimental duck and ch...
TL;DR: It is concluded that broiler-breeder progenies from 30- to 50-wk-old grandparents vaccinated with the AAV 8/11 vaccine were adequately protected against challenge with theAAV 8 and 11 serotypes and the Stanford strain.
Abstract: An avian adenovirus (AAV) was isolated from liver samples of two 2-wk-old broiler-breeder flocks obtained from grandparents vaccinated at 10 and 17 wks of age with an autogenous inactivated vaccine containing the European AAV 8 (8565 strain) and 11 (1047 strain) serotypes (AAV8/11 vaccine). Affected broiler-breeders exhibited clinical signs and macroscopic and microscopic lesions associated with inclusion body hepatitis (IBH). The isolated adenovirus, identified as Stanford, was molecularly characterized as European serotype 9. The pathogenicity of the Stanford strain was confirmed after inoculation of specific-pathogen-free (SPF) chickens at 1–7 days of age, causing 100% and 20% mortality, respectively. The level of protection against IBH was evaluated in two broiler-breeder progenies from AAV 8/11–vaccinated grandparent flocks and a commercial broiler flock by challenge at 1 or 7 days of age with the AAV 8 and 11 serotypes and/or the Stanford strain. The broiler-breeder progenies and the commer...