Detection of subgroup J avian leukosis virus infection in Australian meat-type chickens.

Objective: To determine the extent of avian leukosis virus subgroup J (ALV-J) infection in Australian broiler breeder flocks, using virus isolation and molecular biological detection. Any resultant ALV-J viral isolates to be characterised by neutralisation cross testing in order to determine antigenic relationships to overseas isolates of ALV-J.

Study Design: Samples of blood, feather pulp, albumen and tumours were obtained from broiler breeder flocks which represented four genetic strains of meat chickens being grown in Victoria, South Australia, NSW and Queensland.

Single and concurrent avian leukosis virus infections with avian leukosis virus-J and avian leukosis virus-A in Australian meat-type chickens.

Australian broiler breeders were screened for avian leukosis viruses (ALVs) (May 2001 to December 2003) as surveillance of measures to reduce the prevalence of ALV-J. Samples of blood (4233), albumen (1122), meconium (99) and tumours (16) were obtained from 93 flocks in six Australian states. Virus isolation was performed in C/O chick embryo fibroblast cultures, which were initially screened by group-specific antigen enzyme-linked immunosorbent assay, with follow-up confirmation using polymerase chain reaction.

Avian infectious laryngotracheitis.

Avian infectious laryngotracheitis (ILT) herpesvirus continues to cause sporadic cases of respiratory disease in chickens world-wide. Sources of transmission of ILT infection are three-fold, namely: chickens with acute upper respiratory tract disease, latently infected 'carrier' fowls which excrete infectious laryngotracheitis virus (ILTV) when stressed, and all fomites (inanimate articles as well as the personnel in contact with infected chickens). Infectious laryngotracheitis virus infectivity can persist for weeks to months in tracheal mucus or carcasses.

Chicken anaemia virus antibody ELISA: problems with non-specific reactions.

For accreditation of CSIRO specific pathogen-free flocks, chicken sera are routinely tested for antibody to chicken anaemia virus (CAV) using a commercially available ELISA kit. On some occasions recently, up to 18.2% positive reactions have been found in individual isolators, with an overall reaction rate of 2.

Avian infectious laryngotracheitis: virus-host interactions in relation to prospects for eradication.

This review examines the virology, immunology and molecular biology of infectious laryngotracheitis virus (ILTV) and its interactions with the chicken, in the context of assessing the feasibility of eradication. Establishment of the latent phase during infection of the host, its central role in biological survival of ILTV and the host-viral events that are associated with reactivation of infection, are considered. In counterpoint there are several features of the biology of ILTV in its natural mode of infection which can be exploited in eradicating this pathogen from intensive poultry production sites.

An enzyme-linked immunosorbent assay for detection of reticuloendotheliosis virus infection in chickens.

An enzyme-linked immunosorbent assay (ELISA) for the detection of reticuloendotheliosis virus (REV) is described. The assay is based on antiserum produced in rabbits against the group-specific (gs) antigen of REV which has a molecular weight of 30 kDa (p30). The p30 for immunisation was obtained by electro-elution from polyacrylamide gels after separation of purified REV by electrophoresis.

Responses of cattle, sheep and poultry to a recombinant vaccinia virus expressing a swine influenza haemagglutinin.

Groups of cattle, sheep and poultry were inoculated with a recombinant vaccinia virus expressing the haemagglutinin of the swine influenza virus A/NJ/11/76. No adverse clinical responses were recorded and none of the animals developed a viraemia when inoculated with the recombinant or wild-type vaccinia virus. Recombinant virus reisolated from lesions in cattle was stable, maintaining its thymidine kinase negative phenotype and ability to express the swine influenza haemagglutinin.

In vitro infection studies with infectious laryngotracheitis virus.

Infectious laryngotracheitis (ILT) virus strains were studied for their ability to infect chicken macrophages, lymphocytes, and kidney cells in vitro. Although macrophages were as susceptible as chicken kidney cells to infection, replication of most virus strains in macrophages was markedly restricted. Only a few isolates induced progressive infections in macrophages, and even with these the donor of the macrophages influenced replication.

Laryngotracheitis (Gallid-1) herpesvirus infection in the chicken. 4. Latency establishment by wild and vaccine strains of ILT virus.

Tracheal organ culture (TOC) techniques utilising multiple-well plastic trays were used to detect and assay latent infection established by infectious laryngotracheitis (ILT) herpesvirus in clinically normal chickens. Between 3 and 16 months after tracheal exposure to wild strain (CSW-1, haemorrhagic tracheitis) ILT virus and 2 to 10 months after exposure to vaccine strain ILT (SA-2), groups of chickens were examined for evidence of infection. Neither the examination of tracheal swabbings in monolayer cell cultures nor the inoculation of tracheal tissue suspensions detected virus, and this result was not influenced by preliminary immunosuppressive treatment of the birds with cyclophosphamide or dexamethasone.

Effect of lymphoid leukosis virus on performance of layer hens and the identification of infected chickens by tests on meconia.

The effect of subclinical infection with lymphoid leukosis virus (LLV) on the productivity traits of layer hens was investigated. In hens that shed gs-antigen of LLV to albumen, onset of sexual maturity was delayed by a mean of 11 days and the number of eggs laid was reduced -by 68 per hen up to 75 weeks of age. Shedding hens laid on average 2 g lighter eggs and of lesser specific gravity.

Gallid-1 herpesvirus infection in the chicken. 3. Reinvestigation of the pathogenesis of infectious laryngotracheitis in acute and early post-acute respiratory disease.

Specific-pathogen-free chickens were infected via the trachea when 4 weeks old with 2000 plaque-forming units (PFU) of the virulent Australian infectious laryngotracheitis (ILT) virus strain CSW-1. Titers of ILT virus in the trachea were greatest (10(7.0) PFU/ml in washings, 10(6.

Antibody to the 32K structural protein of infectious bursal disease virus neutralizes viral infectivity in vitro and confers protection on young chickens.

Chicken sera containing IgG antibodies specific for the 32 000 (32K) mol. wt. structural polypeptide of infectious bursal disease (IBD) virus, as assessed by Western blotting, neutralized the in vitro infectivity of tissue culture-adapted IBD virus.

Variation in susceptibility to avian sarcoma viruses and expression of endogenous avian leukosis virus antigens in specific pathogen-free chicken lines.

Five lines of chickens maintained as specific pathogen-free flocks in Australia were characterized in relation to endogenous antigens and endogenous avian leukosis virus expression. Embryos of line N were predominantly of C/E phenotype, uniformly positive for group-specific antigen and chick helper factor (gs+chf+) and 38% expressed endogenous virus at a very low titre. Embryos of line M4 were uniformly of C/ABE phenotype and were either gs+chf+ or gs-chf+.

Laryngotracheitis herpesvirus infection in the chicken. II. The adoptive transfer of resistance with immune spleen cells.

Protection against virulent infectious laryngotracheitis (ILT) virus was successfully transferred between inbred white leghorn chickens with spleen cells or peripheral blood leukocytes from immune cock birds. Resistance to infection could be demonstrated 7 to 8 days, but not 2 days after cell-transfer. Both hyperimmune spleen cells and memory spleen cells conferred resistance to infection, while the transfer of non-immune spleen cells failed to protect the chickens.

Development of the normal gastrointestinal microflora of specific pathogen-free chickens.

The development of the normal intestinal microflora of the small intestine, caecum and large intestine of specific pathogen-free (SPF) chickens, was studied in the period from hatching to 84 days of age. No bacteria were detected in any of the sites at hatchery (day 1), but by day 3 significant levels of faecal streptococci and coliforms were isolated from all sites. The flora of the small intestine was limited to faecal streptococci and coliforms for the first 40 days and then lactobacilli became established and dominated the flora.

Practical application of ELISA for detection of vertical transmission of leukosis virus in commercial layer hens.

The efficiency of enzyme-linked immunosorbent assay (ELISA) for detection of congenital transmission of exogenous lymphoid leukosis virus (LLV) was examined using both vaginal swabs and albumen samples obtained from two layer flocks. Approximately 100 hens were studied in each flock by the ELISA and phenotypic mixing tests. ELISA testing on vaginal swabs identified 25/27 (92.

Laryngotracheitis herpesvirus infection in the chicken: the role of humoral antibody in immunity to a graded challenge infection.

The clinical responses of SPF White Leghorn chickens to graded levels of infection with virulent (wild-strain) infectious laryngotracheitis (ILT) herpesvirus, administered by the tracheal route, were investigated in chickens from 1 day to 8 weeks of age. In 1-day-old chickens 40 plaque forming units (PFU) of ILT virus caused 55% mortality within 8 days. At least 500 PFU was needed to achieve comparable mortality at 3 weeks of age and this increased to 4,500 PFU of ILT virus by 6 to 8 weeks of age.

Inhibition of glycosylation by corynetoxin, the causative agent of annual ryegrass toxicity: a comparison with tunicamycin.

The biological activities of corynetoxins, the causative agents of annual ryegrass toxicity, were compared with those of the closely related tunicamycins and found to be essentially identical. Both showed similar antibiotic activity against Newcastle disease virus and a range of gram-positive bacteria. In preparations of rat liver rough microsomes they also strongly inhibited the uridine diphospho-N-acetylglucosamine (UDP-GlcNAc):dolichol-P N-acetylglucosamine-1-phosphate (GlcNAc-1-P) transferase, an enzyme essential for N-glycosylation of glycoproteins.

Development and evaluation of an ELISA for the detection of antibody to infectious laryngotracheitis virus in chickens.

An enzyme-linked immunosorbent assay (ELISA) for the detection of antibody to infectious laryngotracheitis (ILT) virus in chickens was developed and compared with the serum-neutralization assay. The ELISA routinely yielded 16-to-32-fold higher titers than the serum-neutralization test. To overcome the requirement for large amounts of purified viral antigen, the microtiter trays were initially coated with an antibody prepared against purified ILT virus.