Showing papers in "Avian Diseases in 2013"
TL;DR: Two of the eight APEC strains tested in chickens were able to induce 25% mortality in 1-day-old chicks, and both groups were multidrug resistant.
Abstract: SUMMARY. Avian pathogenic Escherichia coli (APEC) infection is responsible for great economic losses to the poultry industry worldwide and there is increasing evidence of its zoonotic importance. In this study, 219 E.coli isolates from 84 poultry flocks in Egypt, including 153 APEC, 30 avian fecal E. coli (AFEC), and 36 environmental E. coli, were subjected to phylogenetic grouping and virulence genotyping. Additionally, 50 of these isolates (30 APEC from colisepticemia and 20 AFEC) were subjected to a moreextensive characterization which included serogrouping, antimicrobial susceptibility analysis, screening for seven intestinal E. coli virulence genes (stx1, stx2, eae, espP, KatP, hlyA ,a ndfliCh7), multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), andin vivo virulence testing. More than 90% of the total APEC examined possessediroN,ompT,hlyF,iss ,a ndiutA, indicating that Egyptian APECs, like their counterparts from the United States, harbor plasmid pathogenicity islands (PAIs). The majority of APEC and AFEC were of phylogenetic groups A, B1, and D. For the 50-isolate subgroup, more than 70% of APEC and 80% of AFEC were multidrug resistant. Among the subgroup of APEC, MLST analysis identified 11 sequence types (ST) while seven STs were found among AFEC. Based on PFGE, the genetic relatedness of APEC and AFEC ranged from 50%–100% and clustered into four primary groups at 50% similarity. Two of the eight APEC strains tested in chickens were able to induce 25% mortality in 1-day-old chicks. APECs were distinguished from AFECs and environmental E. coli by their content of plasmid PAI genes, whereas APEC isolated from colisepticemia and AFEC were not distinguishable based on their antimicrobial resistance patterns, as both groups were multidrug resistant. Avian E. coli strains from broiler flocks in Egypt show similar sequence types to E. coli associated with human infection.
59 citations
TL;DR: The age at which a vaccinated chicken elicits an immunologic response to the HVT/ND prepared for this study, and thus is protected from ND virus, was assessed in commercial broiler chickens after in ovo vaccination of 18-day-old embryos.
Abstract: SUMMARY Newcastle disease (ND) is prevalent worldwide and causes significant clinical and economic losses to the poultry industry. Current vaccine programs using live attenuated vaccines and inactivated vaccines have limitations, and new vaccines with distinct features are needed. To offer an alternative solution to control ND, a turkey herpesvirus vector Newcastle disease vaccine (HVT/ND) expressing the fusion gene of Newcastle disease virus (NDV) has been developed. First, immunogenicity of the HVT/ND was evaluated in specific-pathogen-free layer chickens after vaccination by the in ovo route to 18-day-old embryos or by the subcutaneous route to 1-day-old chicks. Antibodies against NDV were detected at 24 days of age using a commercial NDV enzyme-linked immunosorbent assay (ELISA) kit and the hemagglutination inhibition test. At least 90% of chickens were protected against challenge with velogenic neurotropic NDV Texas GB strain (genotype II; pathotype velogenic) at 4 wk of age, while none of the nonvac...
58 citations
TL;DR: It is illustrated that backyard chickens do not seem to pose a major risk to public health, although zoonoses do comprise a notable portion (5.9% of all infectious cases) of isolated agents.
Abstract: A 5-yr retrospective study was conducted to characterize the spectrum of diseases causing mortality in 1301 backyard chickens submitted to the California Animal Health and Food Safety laboratory in Davis, California. Infectious diseases were diagnosed in the majority (60.4%). Viral diseases comprised 50% of the infectious entities, followed by bacterial diseases with an incidence of 39%. Marek's disease in the viral group and Escherichia coli in the bacterial group were the most commonly diagnosed infectious diseases. Zoonotic agents including Aspergillus sp., Salmonella sp., Listeria sp., Mycobacterium sp., Candida sp., and Baylisascaris sp. were detected in 46 (3.5%) birds. Among noninfectious conditions, fatty liver hemorrhagic syndrome and reproductive tract adenocarcinoma were the leading causes of mortality. This analysis provides an overview of backyard chicken diseases for practitioners and avian pathologists working with backyard poultry. In addition, this study illustrates that backyard chickens do not seem to pose a major risk to public health, although zoonoses do comprise a notable portion (5.9% of all infectious cases) of isolated agents.
58 citations
TL;DR: Although there has been significant progress in the understanding of the functions of a number of viral genes in the pathogenesis of the disease, the characteristics of the latent infection, how it differs from tumor phase, and whether latency is a prerequisite for the tumor phase are all important questions still to be answered.
Abstract: Despite the remarkable progress in our understanding of Marek's disease (MD) and the causative Marek's disease virus (MDV) biology, a number of major features of this complex viral disease remain unknown. Significant information on critical aspects of virus latency in lymphoid cells, and the virus-host interaction in MDV-induced lymphoma, remains to be identified. Moreover, the nature of the unique milieu of the feather follicle epithelial cell that allows cytolytic infection to continue, despite maintaining the latent infection in the lymphoid cells, is not fully understood. Although there has been significant progress in our understanding of the functions of a number of viral genes in the pathogenesis of the disease, the characteristics of the latent infection, how it differs from tumor phase, and whether latency is a prerequisite for the tumor phase are all important questions still to be answered. Reticuloendotheliosis virus-transformed cell lines have been shown to support MDV latency in a manner almost identical to that seen in MDV-transformed cell lines. There are increasing data on the role of epigenetic regulation, including DNA methylation and histone modifications, in maintaining viral latency. Onset of MD tumor is relatively rapid, and recent studies based on chromosomal integration and T-cell repertoire analysis demonstrated the clonal nature of MD lymphomas. Among the viral determinants of oncogenicity, the basic leucine zipper protein Meq is considered to be the most important and the most extensively studied. Deleting the Meq proteins or abolishing some of the important interactions does affect the oncogenicity of the virus. In addition, the noncoding sequences in the viral genome, such as the viral telomerase RNA and the virus-encoded microRNAs, also have significant influence on MDV-encoded oncogenesis.
52 citations
TL;DR: A candidate live vaccine for avian pathogenic Escherichia coli (APEC) was constructed from a virulent field APEC O78 strain by mutation of the aroA gene, highly similar to the parent wild-type strain in respect of colony morphology, motility, growth in suspension, hemagglutination, Congo Red binding, HEp-2 cell adhesion, and the elaboration of surface antigens type 1 fimbriae and flagella.
Abstract: A candidate live vaccine for avian pathogenic Escherichia coli (APEC) was constructed from a virulent field APEC O78 strain by mutation of the aroA gene. The mutant was highly similar to the parent wild-type strain in respect of colony morphology, motility, growth in suspension, hemagglutination, Congo Red binding, HEp-2 cell adhesion, and the elaboration of surface antigens type 1 fimbriae and flagella, although production of curli fimbriae was reduced marginally. The mutant proved avirulent when inoculated into 1-day-old chicks by spray application and when presented again in the drinking water at 7 days of age. Chickens and turkeys vaccinated with an O78 aroA mutant were protected against a challenge at 6 wk of age by virulent APEC strains.
48 citations
TL;DR: Infection with C. jejuni affected the incidence of hock marks and pododermatitis in both breeds of birds, but the differences were greater with the fast-growing breed compared with the uninfected control birds.
Abstract: SUMMARY Campylobacter spp. are frequently carried by poultry, but they are not believed to cause significant disease in these animals. Modern poultry breeds have been selected to grow rapidly under intensive conditions, but recently, consumers have moved toward purchasing birds produced in higher welfare, free-range or organic systems. Birds reared in these systems tend to be a slower growing breed and are fed a different diet. Birds reared in such systems are stocked at a lower density compared with the standard conventional broilers, and they have access to environmental enrichment, such as perches. In previous research, these slower growing birds have been shown to have different levels of Campylobacter carriage in commercial rearing conditions, but the reasons for, and effect of, these different levels are unknown; is it the bird breed, diet, or environmental conditions? In this study, experimental flocks of fast- and slow-growing breeds of broiler chickens were reared to a standard commercial slaught...
44 citations
TL;DR: A questionnaire was widely distributed in 2011 to estimate the global prevalence of Marek's disease (MD) and gain a better understanding of current control strategies and future concerns and indicated increasing MD incidence was likely due to higher virulent strains, while the presence of other immunosuppressive diseases was a more common explanation.
Abstract: A questionnaire was widely distributed in 2011 to estimate the global prevalence of Marek's disease (MD) and gain a better understanding of current control strategies and future concerns. A total of 112 questionnaires were returned representing 116 countries from sources including national branch secretaries of the World Veterinary Poultry Association, vaccine, breeder, and production companies, as well as MD researchers from various backgrounds. Each country listed on a questionnaire was recorded as an individual entry, and on average there were 2.0 entries per country (median 1; range 1-13). All flock types were listed as having increased MD incidence during the last 10 yr in close to 50% of countries by at least one respondent, with the majority of these countries located within French-speaking Africa, Eastern Europe, East Asia, and South America. Only 18 countries (16%) indicated increasing MD incidence was likely due to higher virulent strains, while the presence of other immunosuppressive diseases was a more common explanation. Increased use of CVI988/Rispens was cited as the most likely reason for decreasing MD incidence in 49 countries (42%). In the United States, MD incidence has continued to decrease during the last 10 yr, reaching a record low in 2007 (0.0008%) as measured by leukosis condemnation rates in broilers at slaughter. However, a recent increase of leukosis condemnations in North Carolina and Pennsylvania needs to be closely monitored.
43 citations
TL;DR: The data obtained in this study indicate that the immune response produced by a spray vaccine against E. coli is mainly a cellular response, especially relevant to the sites in contact with the pathogen.
Abstract: SUMMARY Avian pathogenic Escherichia coli is a current problem in the poultry industry, causing mortality and economic losses. This paper evaluates the dynamics in immune response after the use of spray vaccination against E. coli and, thereby, seeks to understand how the vaccine can provide protection. During the early stages of response to vaccination the presence of antigen-presenting cells is predominant, but these diminish within the first 7 days after vaccination. The immune correlate of protection of vaccination using the E. coli vaccine Poulvac E. coli (aroA-deficient mutant strain) probably does not depend on the production of circulating antibodies (as assessed through the presence of B lymphocytes) and is linked to the presence of CD4+TCRVβ1+. These cells act on mucosa tissue stimulating the production of immunoglobulin A. Vaccination stimulated a high state of immunocompetence, as assessed by measurement of several cellular subsets. This state of “immune alertness,” however, may be associated ...
43 citations
TL;DR: This review will focus on the recent advances that have been made in the discovery, description, and characterization of the multitude of viruses that reside in the poultry gut.
Abstract: SUMMARY Despite the importance of the poultry gut, remarkably little is known about the complex gut microbial community. Enteric disease syndromes such as runting-stunting syndrome in broiler chickens and poult enteritis complex in young turkeys are difficult to characterize and reproduce in the laboratory. A great deal of work has been done to characterize the bacterial population in the poultry gut, leading to useful performance-based interventions such as direct-fed microbial preparations. Advances in the application of rapid molecular diagnostics and the advent of the next generation of nucleic acid sequencing have allowed researchers to begin to decipher the microbial community in complex environmental samples. Researchers have made great strides recently in placing names to some of the unknown and undescribed small viruses in the poultry gut such as parvoviruses, picornaviruses, picobirnavirus, and calicivirus. Investigation into the novel avian astroviruses continues, and recent progress has been m...
43 citations
TL;DR: These studies provide strong evidence that detection and quantitation of Marek's disease virus serotype 1, HVT, and MDV-2 in poultry house dust using qPCR is robust, sensitive, reproducible, and meaningful, both biologically and commercially.
Abstract: SUMMARY. Results are presented from four studies between 2002 and 2011 into the feasibility of routinely monitoring Marek's disease virus serotype 1 (MDV-1) in broiler house dust using real-time quantitative PCR (qPCR) measurement. Study 1 on two farms showed that detection of MDV-1 occurred earlier on average in dust samples tested using qPCR than standard PCR and in spleen samples from five birds per shed assayed for MDV-1 by qPCR or standard PCR. DNA quality following extraction from dust had no effect on detection of MDV-1. Study 2 demonstrated that herpesvirus of turkeys (HVT) and MDV serotype 2 (MDV-2) in addition to MDV-1 could be readily amplified from commercial farm dust samples, often in mixtures. MDV-2 was detected in 11 of 20 samples despite the absence of vaccination with this serotype. Study 3 investigated the reproducibility and sensitivity of the qPCR test and the presence of inhibitors in the samples. Samples extracted and amplified in triplicate showed a high level of reproducibility e...
39 citations
TL;DR: It was determined that most of these Newcastle disease virus isolates recovered from the pigeons belonged to a relatively poorly studied sublineage VIb/2, which is equivalent to class II genotype VIb.
Abstract: SUMMARY. Monitoring programs for highly dangerous avian diseases in the Russian Federation from 2001 to 2009 detected 77 samples that were PCR positive for avian paramyxovirus serotype-1 (APMV-1) from sick or dead feral and domestic pigeons. Nucleotide sequences of the fusion (F) gene, including a nucleotide sequence encoding the F protein cleavage site, were determined for these isolates. All of the studied isolates possessed virulent F0 protein cleavage sites (112KRKKRF117, 112RRQKRF117, or 112KRQKRF117). Intracerebral pathogenicity index (ICPI) values determined for seven of the isolates exceeded the value of 0.7 (the range from 0.8 to 1.41). Based on partial genome sequencing and phylogenetic analysis, the isolates were assigned to two individual sublineages within class II genotype VIb. It was determined that most of these Newcastle disease virus isolates (70/77) recovered from the pigeons belonged to a relatively poorly studied sublineage VIb/2. The complete nucleotide sequence of the genome for the...
TL;DR: Results indicate divergence within TARVs as well as from enteric viruses, which needs to be confirmed by complete genome sequence analysis.
Abstract: SUMMARY. During the spring and summer of 2011, the Minnesota Veterinary Diagnostic Laboratory at the University of Minnesota received 14 submissions of 15-to-18-week-old tom turkeys that were recumbent with wing tip bruises (“wing walkers”) and uni- or bilateral swelling of the hock (tibiotarsal) joints. Gastrocnemius or digital flexor tendons were occasionally ruptured. A total of five turkey arthritis reoviruses (TARV-MN1 through TARV-MN5) were isolated in specific-pathogen-free embryonated chicken eggs and QT-35 cells. The identity of the isolates was confirmed by electron microscopy, reverse transcription-polymerase chain reaction, and gene sequence analysis. BLAST analysis on the basis of a 880 bp nucleotide sequence of the S4 gene confirmed all isolates as a reovirus. Phylogenetic analysis divided the five isolates into two subgroups: subgroup I containing TARV-MN1, -2, -3, and -5, and the other subgroup containing TARV-MN4. Isolates in subgroup I had a similarity of 97%–100% with each other, while ...
TL;DR: The findings show that there is emerging drug resistance in APEC associated with colibacillosis in Zimbabwe, and the observed high level of multidrug resistance could hamper the treatment of colIBacillotic disease in Zimbabwe.
Abstract: Colibacillosis, a disease caused by avian pathogenic Escherichia coli (APEC), can lead to great economic losses in the poultry industry. The aim of this study was to determine the prevalence of antibiotic resistance and antibiotic resistance patterns in APEC in Zimbabwe. From 503 chickens diagnosed with colibacillosis, 103 E. coli isolates were obtained. Isolation and identification of E. coli were carried out using microscopy and biochemical tests. The disc diffusion method was used to determine antibiotic susceptibility of the isolates to 8 commercial antibiotics. Many isolates exhibited resistance to more than one antibiotic. Antibiogram profiles indicated maximum resistance to tetracycline (100%), bacitracin (100%), and cloxacillin (100%) and a high prevalence of resistance to ampicillin (94.1%). However; there were high prevalences of sensitivity to ciprofloxacin (100%) and gentamycin (97.1%). The isolates showed moderate rates of sensitivity to chloramphenicol and neomycin. All isolates in this study showed multidrug resistance because they were all resistant to 3 or more antibiotics. Seven multidrug resistance patterns were observed. The most common pattern (resistance to ampicillin, bacitracin, cloxacillin, and tetracycline) was exhibited by 30 isolates. Our findings show that there is emerging drug resistance in APEC associated with colibacillosis in Zimbabwe. The observed high level of multidrug resistance could hamper the treatment of colibacillosis in Zimbabwe.
TL;DR: The results suggest that HVT/LT is a safe and efficacious vaccine for control of laryngotracheitis (LT), and the vaccine did not transmit laterally from vaccinated chickens to commingled nonvaccinated chickens.
Abstract: SUMMARY Turkey herpesvirus vector laryngotracheitis vaccine (HVT/LT) expressing the glycoprotein B gene of laryngotracheitis virus (LTV) has been developed. In vitro growth kinetics of HVT/LT were similar to those of parental turkey herpesvirus (HVT), FC-126 strain. Genetic and phenotypic stabilities of HVT/LT after in vitro (in cell culture) or in vivo (in chickens) passage were confirmed by various assays, including Southern blot analysis, western blot analysis, and an indirect immunofluorescence assay. Safety of HVT/LT was assessed by an overdose study as well as by a backpassage study in specific-pathogen-free (SPF) chickens. The overdose study indicated that HVT/LT did not cause any adverse effects in chickens. The backpassage study confirmed that HVT/LT does not revert to virulence after five passages in chickens. The vaccine did not transmit laterally from vaccinated chickens to commingled nonvaccinated chickens. Efficacy of HVT/LT was evaluated in SPF layer chickens after vaccination by the subcut...
TL;DR: It is found that detection of IBV vaccine virus early after administration, regardless of strain or route, correlated with protection against homologous challenge and may be a good indicator of vaccine efficacy in the field because humoral antibody titers are typically low or undetectable after vaccination.
Abstract: SUMMARY Infectious bronchitis virus (IBV) causes an upper respiratory tract disease in chickens and is highly contagious. Many different types of the virus exist, but only a few types are used as attenuated live vaccines in the commercial poultry industry. Of the vaccine types used, the Arkansas (Ark)–type virus is most frequently reisolated from vaccinated broilers. Previous research has suggested that incomplete clearance of Ark-type vaccine virus plays a role in the inadequate protection observed when vaccinated broilers are challenged with pathogenic Ark virus. In this study, we examine routes of vaccine administration using multiple IBV types including Ark in an effort to understand why Ark vaccines do not provide good protection and persist in commercial broilers. We found that interference between different types of IBV vaccines was not occurring when combined and administered using a commercial hatchery spray cabinet. Also, Ark vaccine virus was not efficacious in 1-day-old broilers when sprayed u...
TL;DR: It is suggested that Cobb chickens may be more susceptible to necrotic enteritis in the field compared with the Ross and Hubbard lines, and pollos Cobb pueden ser más susceptibles to enteritis necrótica in the campo en comparación with las líneas Hubbard y Ross.
Abstract: SUMMARY Necrotic enteritis is an enteric disease of poultry resulting from infection by Clostridium perfringens with coinfection by Eimeria spp. constituting a major risk factor for disease pathogenesis. This study compared three commercial broiler chicken lines using an experimental model of necrotic enteritis. Day-old male Cobb, Ross, and Hubbard broilers were orally infected with viable C. perfringens and E. maxima and fed a high-protein diet to promote the development of experimental disease. Body weight loss, intestinal lesions, and serum antibody levels against α-toxin and necrotic enteritis B-like (NetB) toxin were measured as parameters of disease susceptibility and host immune response. Cobb chickens exhibited increased body weight loss compared with Ross and Hubbard breeds and greater gut lesion severity compared with Ross chickens. NetB antibody levels were greater in Cobb chickens compared with the Ross or Hubbard groups. These results suggest that Cobb chickens may be more susceptible to necr...
TL;DR: The data indicate that ChPV alone induces RSS in broilers and is important determinant in the complex etiology of enteric diseases of poultry.
Abstract: SUMMARY Previously we identified a novel parvovirus from enteric contents of chickens that were affected by enteric diseases Comparative sequence analysis showed that the chicken parvovirus (ChPV) represented a new member in the Parvoviridae family Here, we describe some of the pathogenic characteristics of ChPV in young broilers Following experimental infection, 2-day-old broiler chickens showed characteristic signs of enteric disease Runting-stunting syndrome (RSS) was observed in four of five experimental groups with significant growth retardation between 7 and 28 days postinoculation (DPI) Viral growth in small intestine and shedding was detected at early times postinoculation, which was followed by viremia and generalization of infection ChPV could be detected in most of the major tissues for 3 to 4 wk postinoculation Immunohistochemistry staining revealed parvovirus-positive cells in the duodenum of inoculated birds at 7 and 14 DPI Our data indicate that ChPV alone induces RSS in broilers a
TL;DR: Results indicate that MDV is common in unvaccinated commercial and village chickens in southern Iraq, that there is limited meq gene sequence variation, that all sequenced samples had a short meq with two four-proline repeats, and that this is consistent with a high level of virulence.
Abstract: SUMMARY. A cross-sectional survey was conducted in six provinces in southern Iraq to determine the point prevalence of Marek's disease virus (MDV) in different chicken populations followed by sequencing the meq gene for phylogenetic analysis and virulence-associated polymorphisms. A total of 109 samples from unvaccinated flocks were analyzed comprising 52 dust and 30 spleen samples from commercial broiler farms and 27 spleens from local layer chickens purchased in the town markets. The overall prevalence of MDV was 49.5% with no significant differences between provinces (P = 0.08) or sample types (P = 0.89). Prevalence ranged from 36.8% in Karbala and Nasiriyah to 65% in Amarah. The percentages of positive samples were 59.1%, 46.7%, and 48.1% in broiler dust, broiler spleen, and layer spleen, respectively. The overall mean (±SEM) Log10 MDV viral copy number per milligram of dust or spleen as determined by quantitative PCR was 1.78 ± 0.19, with no significant differences between provinces (P = 0.10)...
TL;DR: The relatively high prevalence of neoplasms in pigeons in the present study is most likely related to the advanced ages of pigeons kept in the research colony.
Abstract: SUMMARY. This study reports the gross and microscopic pathology of naturally occurring neoplasms in adult pigeons that were presented for necropsy at the Indiana Animal Disease Diagnostic Laboratory from 2001 to 2011. The study population consisted of white carneau and mixed-breed pigeons used in behavioral studies in the Department of Psychological Sciences at Purdue University. Twelve types of neoplasms or proliferative disorders were identified in 28 of 83 pigeons (33.7%). Five pigeons had two or three types of neoplasms–proliferative disorders. Of the 83 pigeons, 11 (13.3%) had seminoma, five (6.0%) had thyroid adenoma, four (4.8%) had lymphoma, four (4.8%) had adenocarcinoma of female reproductive tract origin, two (2.4%) had pulmonary carcinoma, and two (2.4%) had cutaneous vascular hamartomas. Also identified were single incidences of dysgerminoma, mesothelioma, liposarcoma, cloacal papilloma, cloacal adenocarcinoma, and gizzard carcinoma. The most frequently occurring tumor was seminoma; 7/11 case...
TL;DR: A unique nucleotide sequence insertion coding for five amino acid residues was observed in all the Brazilian variant viruses (BR-I and BR-II genotypes) and results show a higher genetic diversity in Brazilian IBV variants than previously described.
Abstract: SUMMARY Infectious bronchitis virus (IBV) is the agent of a highly contagious disease that affects domestic fowl (Gallus gallus). Recent reports showed a high prevalence of one main IBV genotype (Brazil or BR-I) with low genetic diversity in commercial poultry flocks from Brazil. This research analyzed IBV positive poultry flocks from different rearing regions to verify the S1 gene variability and geographic distribution of variant IBV strains in recent years (2010 and 2011). Samples of IBV-positive flocks were obtained from 60 different farms. Forty-nine partial S1 gene sequences were determined and aligned for phylogenetic and amino acid similarity analyses. Eleven samples (22.4%) were similar to Massachusetts vaccine strains (Mass genotype) and 34 samples (69.4%) to the previously characterized Brazilian BR-I genotype. Interestingly, the remaining four samples (8.2%) clustered into a new IBV variant genotype (Brazil-II or BR-II), divergent from the BR-I. A unique nucleotide sequence insertion coding fo...
TL;DR: It is demonstrated that houseflies could serve as vectors in HPAI-H5N1 virus transmission in chickens under experimental conditions.
Abstract: SUMMARY In this study, laboratory-reared houseflies were experimentally exposed to the high pathogenicity avian influenza virus (HPAI) subtype H5N1 virus to evaluate the houseflies as vectors in HPAI-H5N1 virus transmission in chickens. One hundred and fifty houseflies (Musca domestica L.) were equally allocated into three groups. Groups 2 and 3 were exposed to the HPAI-H5N1 virus by allowing the flies to consume food containing the virus for 15 min, while the flies in group 1 were allowed to consume H5N1-free food and would serve as a negative control group. Group 2 flies were euthanatized immediately after H5N1 exposure, while group 3 were held at room temperature for 24 hr and euthanatized. The houseflies in the transmission of the HPAI-H5N1 virus were examined by challenging three groups of housefly homogenates into layer chickens via the oral drop. Morbidity and mortality were observed for 14 days, and virus shedding monitored via oropharyngeal swabs (OS) and cloacal swabs (CS), which were collected ...
TL;DR: The results indicate the multivalent VLPs maintained the antigenic integrity of the variant and classic viruses and have the potential to serve as a multivalent vaccine for use in breeder-flock vaccination programs.
Abstract: SUMMARY. Nucleotide sequences that encode the pVP2 proteins from a variant infectious bursal disease virus (IBDV) strain designated USA08MD34p and a classic IBDV strain designated Mo195 were produced with the use of reverse-transcriptase–polymerase chain reaction (RT-PCR) and cloned into a pGEM-T Easy vector. A nucleotide sequence that encodes the VP3 protein was also produced from the USA08MD34p viral genome with the use of RT-PCR and cloned into a pGEM-T Easy vector. The VP3 and pVP2 clones were inserted into the pVL1393 baculovirus transfer vector and sequenced to confirm their orientation to the promoter and to ensure they contained uninterrupted open reading frames. Recombinant baculoviruses were constructed by transfection in Sf9 cells. Three recombinant baculoviruses were produced and contained the USA08MD34p-VP3, USA08MD34p-pVP2, or Mo195-pVP2 genomic sequences. Virus-like particles (VLPs) were observed with the use of transmission electron microscopy when the USA08MD34p-VP3 baculovirus was co-ino...
TL;DR: It is suggested that outbreaks of adenoviral gizzard erosion can lead to significant economic losses in Germany and may be caused by an unusual virulent FAdV-1 strain.
Abstract: SUMMARY. Avian adenovirus infections cause important disease complexes in chickens, but many of the viruses also infect chickens without resulting in overt disease. Previously several outbreaks of gizzard erosions caused by a fowl adenovirus A serotype-1 (FAdV-1) were reported from Japan. Here we report an outbreak of gizzard erosions in 12 broiler flocks in Germany in 2011. Chickens had a reduced daily weight gain and a higher total mortality rate of up to 8%. The birds showed a severe detachment of the koilin layer and ulcerative to necrotizing lesions of the underlying mucosa. Histopathologically, necrotizing ventriculitis with basophilic, intranuclear inclusion bodies in epithelial cells was diagnosed. Immunohistochemistry, egg culture, and electron microscopic examination revealed adenovirus-like particles in the samples. No concurrent infectious agent could be identified. The virus was genotyped as FAdV-1 by PCR and subsequent sequencing. Phylogenetic analysis of the hexon loop L1 gene yielded 100% ...
TL;DR: The results confirmed the accuracy and sensitivity of dust DNA extraction and subsequent q-PCR and showed that differences in virus levels between dust samples truly reflect differences in shedding, demonstrating that measurement of the virus in dust can be used to monitor accurately both the infection status of the chickens and environmental contamination by MDV.
Abstract: SUMMARY. To assess the effect of various vaccine strains on replication and shedding of virulent Marek's disease virus from experimentally infected chickens, quantitative PCR (q-PCR) methods were developed to accurately quantify viral DNA in infected chickens and in the environment in which they were housed. Four groups of 10 chickens, kept in poultry isolators, were vaccinated at 1 day old with one of four vaccines covering each of the three vaccine serotypes, then challenged with very virulent MDV strain Md5 at 8 days of age. At regular time-points, feather tips were collected from each chicken and poultry dust was collected from the air-extract prefilter of each isolator. DNA was extracted from feather and dust samples and subjected to real-time q-PCR, targeting the US2 gene of MDV-1, in order to measure Md5 level per 104 feather tip cells or per microgram of dust. Accuracy of DNA extraction from dust and real-time q-PCR were validated by comparing either q-PCR cycle threshold values or the calculated...
TL;DR: Results suggest that regions on chromosomes 2, 3, 4, 9, 15, 18, and 21 are associated with Marek's disease resistance and can be used for selection and that accounting for the size of progeny groups has a large impact on correct localization of such genomic regions.
Abstract: SUMMARY. A genome-wide association study (GWAS) using Bayesian variable selection was performed to determine genomic regions associated with mortality due to Marek's disease virus (MDV) infection in layers. Mortality (%) under experimental disease challenge (500 plaque-forming units of a very virulent plus MDV strain) was recorded for progeny groups (average 15.5 birds; range 3 to 30) of 253 genotyped sires from four generations of a brown-egg layer line. An additional generation of 43 sires with progeny data was used to validate results. Sires were genotyped with a 42K Illumina single-nucleotide polymorphism (SNP) chip. Methods BayesB (π = 0.995) and BayesCπ, with or without weighting residuals by the size of progeny groups were applied. The proportion of genetic variance contributed by SNPs within each 1-megabase (Mb) genomic region was quantified. Average mortality was 33% but differed significantly between generations. Genetic markers explained about 11% of phenotypic variation in mortality. Correl...
TL;DR: In this article, selected 10-to-21-day-old broiler chickens from flocks undergoing runting-stunting syndrome were found to have significant pancreatic damage, grossly and histologically.
Abstract: SUMMARY Selected 10-to-21-day-old broiler chickens from flocks undergoing runting-stunting syndrome were found to have significant pancreatic damage, grossly and histologically. Six reoviruses, with sequences that varied, both from each other and from S1133 reovirus, were isolated from these pancreases and from pancreases of specific-pathogen-free leghorn sentinels placed on two of the broiler farms for 7 days.
TL;DR: A limited outbreak of nephropathogenic infectious bronchitis (NIB) occurred in three Delmarva (DMV) commercial broiler chicken flocks in 2011, and serologic testing of broiler flocks found <3% tested to possess specific antibodies to DMV/1639/11, indicating the virus had not become established in the region.
Abstract: SUMMARY. A limited outbreak of nephropathogenic infectious bronchitis (NIB) occurred in three Delmarva (DMV) commercial broiler chicken flocks in 2011. Isolates of NIB virus (NIBV)—DMV/1639/11, DMV/3432/11, and DMV/3902/11—were characterized by sequence analysis of the N-terminal subunit (S1) of the spike (S) gene. Findings indicated that the isolates were identical to each other and to PA/9579A/10, a 2010 isolate from poultry in Pennsylvania. The 2010 and 2011 isolates appear to have originated from a 1997–2000 NIB outbreak in Pennsylvania. DMV/1639/11 and PA/9579A/10 were determined to be nephropathogenic in susceptible chickens, yielding virus reisolations from kidney and inducing characteristic interstitial nephritis microscopic lesions. In a controlled laboratory study, 40% of chickens vaccinated with a combination live vaccine containing infectious bronchitis virus (IBV) strains Massachusetts (Mass) + Connecticut (Conn) were positive on virus isolation attempts after challenge with DMV/1639/11, comp...
TL;DR: This study retrospectively compares the differences between the FDA and CEQAP programs with respect to their SE environmental sampling surveillance results as well as investigating the main effects of the presence of SE in the farm environment.
Abstract: SUMMARY. Between July 2007 and December 2011, 2660 environmental drag swab samples were collected in total from California layer flocks on behalf of the California Egg Quality Assurance Program (CEQAP), the egg safety rule (21 CFR Parts 16 and 118) of the Food and Drug Administration (FDA), or both. The samples were processed by the California Animal Health and Food Safety Lab, and positive or negative results for Salmonella enterica serovar Enteritidis (SE) were recorded. This study retrospectively compares the differences between the FDA and CEQAP programs with respect to their SE environmental sampling surveillance results. To accomplish this comparison, two different CEQAP (new and old) data sets representing different SE environmental surveillance approaches in the life of the flock were compared against each other and against the FDA's SE environmental testing plan. Significant differences were noted between the CEQAP and FDA programs with respect to the prevalence of SE in the farm environment. Ana...
TL;DR: Aflatoxins present in the feed determined an increase in the activity of pancreatic enzymes in broilers, affecting the digestibility of the diet, thereby leading to losses in performance and productivity.
Abstract: SUMMARY The aim of this research was to evaluate, on a weekly basis, the effects of aflatoxins on the activity of digestive enzymes (α-amylase, lipase, and trypsin) in the pancreas as well as on the performance and histology of pancreas in broiler chickens over the course of 42 days. One thousand and eighty 1-day-old male Cobb broilers were divided into four treatments with 18 replicates and 15 birds per replicate (i.e., 270 broilers per treatment). Treatments were established according to the amount of aflatoxins added to the diet, as follows: T1 = 0 mg of aflatoxins per kilogram of feed (mg/kg); T2 = 0.7 mg/kg; T3 = 1.7 mg/kg; and T4 = 2.8 mg/kg. Pancreas sample collection was performed from one bird out of each replicate at 7, 14, 21, 28, 35, and 42 days of experiment, which yielded a total of 18 samples per treatment on each collection. Each sample was homogenized in distilled water, frozen in liquid nitrogen, lyophilized, and stored at −20 C until analysis. Performance parameters (body weight...
TL;DR: Results indicated that the contamination of live vaccines by CAV may have influenced CAV epidemiology in the Brazilian and Argentinian poultry industry.
Abstract: The presence of infectious chicken anemia virus (CAV) was detected in a previous study by nested-PCR as a contaminant in seven commercial vaccines, produced in the 1990s by three different manufacturers, prepared against the most relevant virus etiologies. In order to phylogenetically characterize the genome and compare it to CAV isolates from Brazil and other parts of the world, sequences of approximately 675 bp of the gene encoding the hypervariable region of VP1 protein of three CAV vaccine contaminant strains were studied. The CAV genome in contaminated vaccines showed high similarity (> 98.9%) with the Brazilian BR91/99 and Argentinian ArgA001028 (> 99%) strains. However, the comparison with the Cuxhaven-1 vaccine strain showed a lower identity of between 96.8% and 97.7%, and comparing it with the CAV26P4 vaccine strain showed an identity between 97.2% and 98.2%; both are available in Brazil. Such differences might be relevant for the highly conserved CAV genome. CAV contaminants were positioned in the same genetic group (clusters) with the Brazilian strain BR91/99 and Argentinian strain ArgA001028. Results indicated that the contamination of live vaccines by CAV may have influenced CAV epidemiology in the Brazilian and Argentinian poultry industry.