This review is focused on the acute form of infectious bursal disease (IBD) caused by very virulent IBD virus (vvIBDV). First described in Europe about 10 years ago, this new form of the disease has rapidly spread all over the world, causing dramatic losses; after a decade, it still represents a considerable threat to the poultry industry. Emergence of the acute forms of the disease has drastically changed the epidemiology of IBD. Although their origin is still under investigation, vvIBDVs have spread all over the world in a very explosive but conserved manner. This raises the question of the origin of vvIBDVs, of the possible existence of reservoirs and of the possible emergence of new, distinct lineages in the future. While it has become clear that amino acids within the variable region of virus protein VP2 account for the molecular basis of antigenic variation, no definite hot spot that determines pathogenicity has been identified. Fingerprints of VP2 on vvIBDVs have to be considered more as common evo...

https://www.tandfonline.com/doi/pdf/10.1080/03079450050045431

Acute infectious bursal disease in poultry: A review

The fluoroquinolones are a series of synthetic antibacterial agents that are undergoing extensive investigation for both human and veterinary use in the treatment of a variety of bacterial infections. These agents work through the inhibition of DNA gyrase, interfering with the supercoiling of bacterial chromosomal material. As a result, these agents are rapidly bactericidal primarily against gram-negative bacteria, mycoplasma, and some gram-positive bacteria, with most having little to no activity against group D streptococci and obligate anaerobic bacteria. Resistance develops slowly and is almost always chromosomal and not plasmid-mediated. However, development of resistance to the fluoroquinolones and transfer of that resistance among animal and human pathogens have become a hotly debated issue among microbiologists. The fluoroquinolones are a current antimicrobial class whose use in veterinary medicine is being scrutinized. From a pharmacokinetic perspective, these agents are variably but well absorbed from the gastrointestinal tract and almost completely absorbed from parenteral injection sites, and they are well distributed to various tissues in the body. The fluoroquinolones are metabolized and renally excreted, with many of them having approximately equal excretion by the hepatic and the renal excretory systems. The primary toxicity observed at therapeutic doses involves the gastrointestinal system and phototoxicity, although at higher doses central nervous system toxicity and ocular cataracts are observed. Administration to immature animals may result in erosive arthropathies at weight-bearing joints, and administration of high doses to pregnant animals results in maternotoxicity and occasionally embryonic death. The fluoroquinolones are approved for indications such as urinary tract infections and soft tissue infections in dogs and cats and colibacillosis in poultry. Approval for bovine respiratory disease in the United States is being sought. Other indications for which the fluoroquinolones have been used in animal health include deep-seated infections, prostatitis, and other bacterial infections resistant to standard antimicrobial therapy.

Fluoroquinolones in animal health

Research on infectious bursal disease--the past, the present and the future.

Sexually transmitted diseases (STDs) have been generally thought of as a small subset of infectious diseases, rather than as an important group of diseases that occur in numerous species. In this paper, we have (1) briefly reviewed theoretical studies on the dynamics of STDs; (2) documented the distribution of STDs in the animal kingdom; and (3) investigated whether STDs have characteristics which distinguish them from other infectious diseases. The dynamics of STDs should differ from those of ordinary infectious diseases because their transmission depends on the frequency rather than density of infectives. With this type of transmission, there is no threshold density for disease spread, and the conditions for host-pathogen coexistence are more restrictive. Nevertheless, a wide variety of disease characteristics may allow a sexually transmitted pathogen to coexist with its host. We found over 200 diseases for which there was evidence of sexual transmission. They occurred in groups as diverse as mammals, reptiles, arachnids, insects, molluscs and nematodes. Sexually transmitted pathogens included protozoans, fungi, nematodes, helminths, and cancerous cell lines, as well as bacteria and viruses. Detailed comparison of the characteristics of sexually transmitted mammalian diseases with those that are transmitted by non-sexual means, showed that STDs cause less mortality, are longer-lived in their hosts, are less likely to invoke strong immune responses, have narrower host-ranges, and show less fluctuation in prevalence over time. These shared features are related to mode of transmission rather than either host or pathogen taxonomic affiliation. This suggests an evolutionary explanation based on shared ecologies rather than one based on phylogenetic history.

Sexually transmitted diseases in animals: ecological and evolutionary implications.

Infectious Bursal Disease

The antigenic and genetic relationships between very virulent (vv) infectious bursal disease viruses (IBDV) from different countries were investigated. Antigenic characterization was performed using an antigencapture ELISA based on a panel of seven neutralizing monoclonal antibodies (Mabs), which probe at least three VP2-located antigenic domains. All these domains are reactive in the Faragher 52/70 (F52/70) reference strain for European classical serotype 1 IBDV. Genomic characterization was achieved by reverse transcription, amplification and direct sequencing of a genome fragment encoding the VP2 variable domain. Eleven vv isolates from France were compared to the British, Dutch and Belgian UK661, DV86 and 849VB viruses, and to an early vv isolate obtained from the Ivory Coast in 1988. All viruses exhibited antigenic profiles characterized by no binding of Mabs 3 and 4. Lack of binding of Mabs 3 and 4 might thus be helpful for differentiating classical and vvIBDVs. None of the non-French strains resemb...

Antigenic and genetic relationships between European very virulent infectious bursal disease viruses and an early West African isolate

Nine monoclonal antibodies (Mabs) to a vaccine strain of infectious bursal disease virus (IBDV) of intermediate virulence were characterized in Western-blot, radioimmunoprecipitation, ELISA additivity, and neutralization assays. At least two distinct serotype 1-specific conformation-dependent overlapping neutralizing antigenic domains were shown to be present on IBDV-VP2, and were respectively probed by Mabs 3 and 4, and by Mabs 6 and 7. Ten serotype 1 vaccine or pathogenic IBDV strains were tested for neutralization. Most mild or intermediate vaccine strains were efficiently neutralized by all Mabs, whereas US variant A, European pathogenic strain Faragher 52/70 and French hypervirulent isolate 89 163 were not neutralized by Mabs 3 and 4. In addition, these two Mabs were shown to bind to the Faragher 52/70 strain, but not to the 89 163 isolate, in an antigen-capture ELISA. These results suggest that a neutralizing epitope is possibly modified in European pathogenic IBDV strains, and that Mabs 3 and 4 may prove useful for antigenic differentiation between European classical and hypervirulent isolates.

Modified activity of a VP2-located neutralizing epitope on various vaccine, pathogenic and hypervirulent strains of infectious bursal disease virus

Summary On the basis of the aligned 16S rRNA sequences of Mollicutes, a pair of primers was chosen for the detection of Mycoplasma gallisepticum. When used in the polymerase chain reaction (PCR), the primers detected a specific amplification of all Mg strains tested, yielding an expected 330 bp product. Amplification was not detected when other Mollicutes or E. coli were used as PCR templates. SPF chickens were experimentally inoculated with two strains of M. gallisepticum or Mycoplasma iowae. Tracheal swabs were collected 8, 15, 20 and 28 days after inoculation, and cultured for mycoplasma or tested by PCR. PCR products were detected by hybridization with a digoxigenin‐labeled probe and by chemilumines‐cence. The results showed that culture was positive for 49/73 swabs while PCR detected 70/72 positive samples. Thus, PCR can provide the basis of a sensitive, specific, rapid and non‐radio‐active method for detecting M. gallisepticum.

https://www.tandfonline.com/doi/pdf/10.1080/03079459308418961

The polymerase chain reaction for Mycoplasma gallisepticum detection.

One-day-old chicks, with or without maternal antibodies against Newcastle disease, were vaccinated by different methods: one group received a live vaccine (Hitchner B1 strain), the second group an oil-adjuvant vaccine, and the third group both vaccines simultaneously. The serological response and the protection of the chicks against challenge were evaluated regularly up to 80 days of age. The best results were obtained when using both vaccines, which induced a good level of protection against the challenge virus strain.

https://www.tandfonline.com/doi/pdf/10.1080/03079457808418256

Vaccination of one-day-old chicks against Newcastle disease using inactivated oil adjuvant vaccine and/or live vaccine.

Seven neutralizing monoclonal antibodies (Mabs) to infectious bursal disease virus (IBDV) were used in an antigen-capture ELISA for the antigenic characterization of 58 IBDV isolates obtained in France since 1989. Fifty-six isolates exhibited an antigenic profile which was different from reference strain Faragher 52/70, and similar to French very virulent IBDV strain 89 163 (no binding of two Mabs). Two strains (3.4%), isolated in 1991 and 1994, showed additional antigenic modifications resulting in suppressed or reduced binding activity of three other Mabs. The two atypical viruses were not re-identified in field samples subsequently collected, hence showing that antigenic variants of IBDV do not tend to replace the antigenically dominant 89 163-like strains that have prevailed in France since 1989.

M. Guittet

Papers

Antigenic and genetic relationships between European very virulent infectious bursal disease viruses and an early West African isolate

Modified activity of a VP2-located neutralizing epitope on various vaccine, pathogenic and hypervirulent strains of infectious bursal disease virus

The polymerase chain reaction for Mycoplasma gallisepticum detection.

Vaccination of one-day-old chicks against Newcastle disease using inactivated oil adjuvant vaccine and/or live vaccine.

Limited antigenic variation among recent infectious bursal disease virus isolates from France.