PubMed Health⌕ Search

Biomedical subjects

A J Forman

Publications and source records attributed to A J Forman.

At least 19 recordsLinked to original sources

Foot and mouth disease: the future of vaccine banks.

The authors briefly review the history of vaccine banks for foot and mouth disease, their current location and their constituent serotypes and strains, together with the occasions on which they have been activated. Experimental studies on emergency vaccines are summarised and areas identified for further investigation. The future of such banks is considered, including the principal strengths and weaknesses of existing banks, and suggestions are made for potential improvements. The fact that the banks have been activated on relatively few occasions over the 25 years of their existence testifies in part to the relatively rare calls which have been made upon them, but also reflects the difficulty in deciding when and how to utilise emergency vaccination. Nevertheless, in an era of increasing global risks of the spread of foot and mouth disease, banks will most certainly continue to have strategic and tactical importance in the control of this most readily communicable of animal diseases.

Animals↗

Infection of pigs with transmissible gastroenteritis virus from contaminated carcases.

Sixteen 6-month-old pigs were exposed to transmissible gastroenteritis (TGE) virus by placing them in close contact with piglets infected at 1 week of age. Fourteen of the older pigs were slaughtered between 1 and 5 d after exposure to infection and their carcases dressed in simulated abattoir conditions. Samples of muscle, bone marrow and carcase lymph nodes were stored at -25 degrees C for at least 30 d and then homogenised and fed to groups of 1-week-old and 3-week-old pigs. Four of 12 one-week-old pigs died and TGE virus was isolated from intestinal contents of one of these. All pigs of both age groups developed neutralising antibody to TGE virus over the ensuing 4 w. The results indicate that carcases from pigs infected with TGE virus can represent a source of infection for susceptible pigs given access to them.

Abattoirs↗

The occurrence of equine arteritis virus in Australia.

This paper reports the first isolation of equine arteritis virus (EAV) in Australia and serological evidence of exposure to EAV in Australian horses. Twelve Standardbred stallions imported from North America were found to shed EAV in semen. One hundred and seven stallions were tested for serum antibodies to EAV and 73% of Standardbred stallions tested were seropositive as compared to 8% of Thoroughbred stallions. Serum antibody was detected in 71% of Standardbred mares, 6% of Standardbred racehorses and 1% of Thoroughbred mares and racehorses. Examination of stored serums demonstrated that EAV had been present in Australia since at least 1975.

Animals↗

A comparison of enzyme-linked immunosorbent assay, complement fixation and virus isolation for foot and mouth disease diagnosis.

A total of 205 epithelial tissue samples were examined for the presence of foot and mouth disease virus by either the complement-fixation (CF) test, enzyme-linked immunosorbent assay (ELISA) and/or by virus isolation in bovine thyroid or kidney cell cultures. The virus was isolated from 134 of the 201 (67%) specimens. Samples, from which virus was isolated, were termed virus-positive samples. The CF test detected viral antigen in 30 (24%) of 123 virus-positive samples, whereas the ELISA detected it in 100 (81%) of these specimens. The ELISA was thus at least 3 times more efficient than the CF test in detecting the virus in epithelial-tissue samples. There were 5 samples from which virus was not isolated but which were positive with the ELISA procedure. The ELISA was particularly useful for testing samples from pigs and for assessing specimens from animals with resolving lesions. The ELISA gave virus type-specific results in 89% of 63 virus-positive cases compared to 40% for the CF test. The ELISA was thus a very useful, accurate and sensitive method for the direct testing of epithelial tissues of affected animals.

Animals↗

The pathogenicity of an avian influenza virus isolated in Victoria.

An influenza virus (H7N7) isolated from an outbreak of disease in chickens in Victoria, was examined for its ability to cause disease in inoculated chickens, turkeys and ducks. The virus was highly pathogenic in chickens and turkeys but produced no clinical disease in ducks. Transmission of infection occurred from inoculated chickens to those in direct contact but other chickens separated by a distance of 3m directly downwind developed neither clinical disease nor antibody to the virus.

Animals↗

Interactions of porcine alveolar macrophages and bone marrow cells with African swine fever virus and virus-infected cells.

Virus yields from porcine alveolar macrophages (AM) infected with African swine fever virus (ASFV) were greater and were achieved more rapidly, when inoculated at a high multiplicity of infection (MOI) than at low MOI. The difference was related to a lower percentage of cells becoming infected after low MOI inoculation. The reduced yields after low MOI were not caused by prolongation of the culture time, by bacterial endotoxins or by production of inhibitory substances by infected AM. Virus-infected AM were not susceptible to lysis in antibody-dependent cell mediated cytotoxicity (ADCC) assays and this was apparently due to a paucity of viral antigen expressed on the cell surface. Uninfected AM did not act as effectors in ADCC. Porcine bone marrow (PBM) cells were effective in mediation of ADCC and their activity was reduced after ASFV infection. Cells separated into adherent and non-adherent populations, depleted by carbonyl iron treatment or separated by Ficoll-Hypaque centrifugation, all showed effector activity in ADCC. The effector cells were not mature neutrophils or lymphocytes and were probably granulocytic precursors.

African Swine Fever Virus↗

The immunological response of pigs and guinea pigs to antigens of African swine fever virus.

Pigs vaccinated with glutaraldehyde-fixed alveolar macrophages (AM) infected with African swine fever virus (ASFV) had an accelerated serological response after subsequent challenge and a slight reduction in levels of viraemia. Vaccination of pigs with detergent-treated infected AM produced no detectable serological response and no protection against homologous challenge. Guinea pigs were vaccinated with glutaraldehyde-fixed ASFV-infected cells, detergent-treated infected cells, detergent-treated infected spleen homogenate, purified ASFV or sonicated infected cells. Antibody was detectable by ELISA after vaccination with all preparations except the detergent-treated infected spleen vaccine. However, vaccination with purified ASFV or sonicated infected cells induced antibodies that were also strongly reactive in antibody-dependent cell-mediated cytotoxicity and complement-mediated lysis assays. If such antibodies are protective, immunization of pigs with purified ASFV or sonicated infected cells may induce a protective immunity.

African Swine Fever↗

The characterisation and pathogenicity of porcine enteroviruses isolated in Victoria.

Approximately 23 viruses were isolated from healthy pigs, pigs with encephalitis, and in cases of reproductive failure. Five viruses were identified as enteroviruses and a total of 10 isolates were shown to cross-react serologically to varying degrees. Twenty viruses were neutralised by a reference antiserum of serotype 8 porcine enterovirus. Intracerebral inoculaton of colostrum-deprived piglets with 2 of the characterised viruses caused lesions of encephalomyelitis which were not induced by oral infection. Intrafoetal inoculation of 2 sows with one characterised faecal isolate caused foetal death and abortion, but no adverse effects followed oral dosage.

Abortion, Veterinary↗

Effect of infectious bovine rhinotracheitis virus infection on bovine alveolar macrophage function.

Bovine alveolar macrophages isolated in culture were assessed for immunological activity in assays for Fc and complement receptors, for phagocytosis, and for effector cell function in antibody-dependent cell cytotoxicity. In the case of uninfected alveolar macrophages, Fc receptors were detected on approximately 94% of macrophages and complement receptors were detected on 39%. Phagocytosis of immunoglobulin G-coated sheep erythrocytes occurred in 58% of macrophages, and phagocytosis of opsonized Candida parapsilosis, mediated by the complement receptor, was observed in 68% of cells. Alveolar macrophages were efficient effector cells in antibody-dependent cell cytotoxicity. Infection of macrophages with infectious bovine rhinotracheitis (IBR) virus resulted in reductions in Fc-mediated receptor activity and phagocytosis after approximately 12 and 6 h, respectively. Complement receptor activity was initially elevated and then markedly reduced. Macrophages retrieved from IBR-immune and -susceptible donors were affected to a similar extent. The ability of macrophages to participate in antibody-dependent cell cytotoxicity was reduced dramatically from 2 h after IBR virus infection, suggesting that IBR virus-infected alveolar macrophages undergo alterations in immunological activity long before morphological changes in the cells become apparent.

Animals↗