Biomedical subjects

V Sivanandan

Publications and source records attributed to V Sivanandan.

47 records · Page 3Linked to original sources

PubMedDate not supplied

Immune profile of infectious bursal disease: I. Effect of infectious bursal disease virus on peripheral blood T and B lymphocytes of chickens.

A comparison was made of absolute numbers of peripheral blood B and T lymphocytes, as defined by the anti-bursal and anti-thymus sera, in chickens infected with infectious bursal disease virus at one day and 3 weeks of age by age-matched controls. Birds were evaluated sequentially at weekly intervals for a period of 8 weeks postinfection. The severity of depressions of B-lymphocyte numbers was found to be age-dependent: the birds infected at one day of age showed a more severe depletion than those infected at 3 weeks of age. The T-lymphocyte numbers were less markedly affected in infected chickens of either age group.

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PubMedDate not supplied

Immune profile of infectious bursal disease (IBD). II. Effect of IBD virus on pokeweed-mitogen-stimulated peripheral blood lymphocytes of chickens.

Pokeweed-mitogen-stimulated peripheral blood lymphocytes from chickens infected with infectious bursal disease virus (IBDV) at 1 day and 3 weeks of age, together with those from uninfected age-matched control chickens, were examined at weekly intervals for their capacity to undergo in vitro terminal differentiation. This study included the determination of cytoplasmic-immunoglobulin (CIg)-containing peripheral blood lymphocytes and those bearing the surface membrane immunoglobulin (SmIg) cells to detect any defect in immunoglobulin synthesis and secretion, respectively. The results of our study indicated that there was a highly significant and pronounced progressive depletion of CIg-containing cells in chickens infected at 1 day of age. These findings suggest that IBDV affected the "immature" or precursor B cells to a far greater extent than mature B lymphocytes.

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PubMedDate not supplied

Immune profile of infectious bursal disease. III. Effect of infectious bursal disease virus on the lymphocyte responses to phytomitogens and on mixed lymphocyte reaction of chickens.

A whole-blood-culture technique was used to sequentially evaluated peripheral blood lymphocyte responses to phytohemagglutinin (PHA) and concanavalin A (Con A) of normal chickens and chickens infected at 1 day or 3 weeks of age with infectious bursal disease virus (IBDV). This method had numerous advantages over the more conventional techniques. A comparative study was made on the percentage of inhibition of responses of peripheral blood lymphocytes to PHA and Con A of 1-day- and 3-week-old IBDV-infected chickens. In both groups, there was a minimum inhibition between 3 and 4 weeks postinfection (PI) and a maximum inhibition at 6 weeks PI. A one-way mixed lymphocyte reaction (MLR) was performed using mitomycin-C-treated cells as stimulator cells obtained from chickens of genetically different strains. Lymphocytes from the experimental birds (control, 1-day-infected, and 3-week-infected groups) were used as the responder cells. The results showed that MLR response of the IBDV-infected chickens was significantly reduced compared with those of the uninfected controls. The degree of lowered response was much more severe in chickens infected at 1 day of age than in those infected at 3 weeks of age.

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PubMedDate not supplied

Effect of avian influenza virus infection on the phagocytic function of systemic phagocytes and pulmonary macrophages of turkeys.

The effects of avian influenza virus (AIV) infection on systemic phagocytes and pulmonary macrophages of turkeys were studied. There was a significant increase (P < 0.0001) in oxidative burst in systemic phagocytes of AIV-inoculated turkeys on 2, 4, 6, and 8 days postinoculation (PI), as measured by chemiluminescence. There was also a significant increase (P < 0.02) in oxidative burst in pulmonary macrophages on day 4 PI. The chemiluminescence response was depressed on 6, 8, and 10 days PI in AIV-inoculated turkeys compared with controls. The increase in oxidative response in both systemic phagocytes and pulmonary macrophages correlated with the peak virus titer in the lungs and trachea of AIV-inoculated inoculated turkeys. Bacterial killing by pulmonary macrophages from AIV-inoculated turkeys was reduced on days 6 and 10 PI compared with uninoculated controls. Histopathological changes in trachea were more pronounced on day 6 PI in AIV-inoculated turkeys; no significant changes were detected in the lungs. These data indicate that compromised functional capacity of pulmonary macrophages predisposes turkeys to secondary bacterial infections.

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PubMedDate not supplied

Effect of temperature on the stability of avian influenza virus antigens under different storage conditions.

The combined effect of time and temperature on the stability of two avian influenza virus (AIV) isolates concentrated with polyethylene glycol (PEG), stored at different temperatures, and used in the preparation of avian influenza vaccine was evaluated in turkeys at 24 hr and at 12, 24, 30, 36, and 42 months of storage. The differences detected between antibodies raised in turkeys by vaccines made from isolates under different storage conditions, times, and temperatures were not significant (P > 0.05), especially with vaccines prepared from one isolate. Virus recovery rates following challenge studies of vaccinated birds were similar. However, birds that were vaccinated twice had lower rates of virus recovery from the trachea, lungs, pancreas, and fecal samples following challenge infection. The results suggest that if stable isolates of AIV can be identified, such isolates can be rapidly concentrated with PEG and stored at -20 C or -196 C for at least 42 months without any loss of potency in the vaccine prepared from these isolates. This would reduce the costs associated with vaccine storage and subsequent expiration dates.

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PubMedDate not supplied

Comparative evaluation of tissue trophism characteristics in turkeys and mallard ducks after intravenous inoculation of type A influenza viruses.

Ten avian type A influenza viruses consisting of seven waterfowl-origin, one pheasant-origin, and two turkey-origin viruses were evaluated for their pathogenicity potential after intravenous inoculation into domestic turkeys and mallard ducks (Anas platyrhynchos). The replicative abilities and tissue trophism properties of each virus isolate were examined in both species. The overall virus-isolation rate and histopathological lesion score were greater in the turkeys than in the ducks. The waterfowl-origin viruses caused more tissue damage in turkeys than in ducks but had a narrower tissue distribution range. The pheasant isolate was extremely pathogenic in turkeys but had limited distribution and little effect in ducks. The turkey isolates were more pathogenic in turkeys than in ducks. The pancreas was the most severely affected organ in turkeys, followed by kidney and liver. The spleen and bursa were the most commonly affected organs in ducks.

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PubMedDate not supplied

Biological and molecular characterization of H13N2 influenza type A viruses isolated from turkeys and surface water.

The pathogenicity potential of two H13N2 influenza viruses, one isolated from turkeys and the other isolated from surface water, was evaluated in turkeys, chickens, and mallard ducks (Anas platyrhynchos) after intracranial and oculonasal inoculation. Both isolates replicated in turkey poults, causing depressed weight gain, morbidity and mortality; both also caused histopathological lesions, such as mild to severe pancreatitis, hepatitis, and nephritis in turkeys. These isolates replicated in mallard ducklings but not in chickens. There was depressed weight gain in ducklings given the H13N2 isolate from water. Neither isolate caused morbidity or mortality in ducklings or chicks after inoculation.

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PubMedDate not supplied

Effect of an H5N1 avian influenza virus infection on the immune system of mallard ducks.

Avian influenza virus (AIV) of waterfowl origin, A/Mallard/Ohio/184/86 (H5N1), was used to evaluate the effect of AIV infection on the functional capabilities of the immune system in mallard ducks. The three main arms of the immune system--humoral, cell-mediated, and cellular--were evaluated. The integrity of the humoral immune system after AIV infection was evaluated by measuring total immunoglobulin and IgG antibody production to sheep erythrocytes and Brucella abortus antigen using hemagglutination and microagglutination assays, respectively. Cell-mediated immunity was evaluated using mitogen/antigen stimulation assays, and by measuring the cutaneous basophilic hypersensitivity response to intradermal phytohemagglutinin-P inoculation. The cellular component of the immune response was evaluated using whole-blood chemiluminescence and bacterial clearance assays. Results showed that infection with this AIV isolate suppressed T-cell function and enhanced macrophage phagocytic activity.

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PubMedDate not supplied

A lipid-conjugated immunostimulating complex subunit vaccine against Salmonella infection in turkeys.

Immunostaining complexes (ISCOMs) are multimeric particles and have been used successfully for presentation of membrane proteins. In this study, outer-membrane proteins (OMPs) from Salmonella heidelberg were incorporated into lipid-conjugated ISCOM particles and evaluated for their use in a vaccine for turkeys against homologous and heterologous Salmonella challenge. Two types of lipid-conjugated ISCOMs were examined: ISCOM-phospholipid and ISCOM-sphingolipid preparations. The turkeys were challenged with one of the three Salmonella serotypes: S. heidelberg, S. reading, or S. enteritidis. The turkeys were monitored for clinical signs, shedding pattern post-challenge, and clearance of the challenge Salmonella from selected internal organs. Vaccines containing OMP with either lipid-conjugated ISCOM preparation produced significantly greater (P < 0.01) immune response than OMP alone. Cloacal swabs from turkeys given OMP along with ISCOM-phospholipid and challenged with a homologous serotype were completely negative for Salmonella. A certain degree of cross-protection against heterologous Salmonella was afforded by both OMP-ISCOM vaccines. The isolation rate of Salmonella from internal organs was significantly lower (P < 0.0001) in vaccinated turkeys than in unvaccinated controls.

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PubMedDate not supplied

A dot immunoblotting assay (dot blot ELISA) for early detection of Newcastle disease antibodies in chickens.

An enzyme-linked immunosorbent assay using nitrocellulose blotting membrane (dot blot ELISA) was developed for the detection of antibodies against Newcastle disease virus (NDV) in chickens. In this method, a nitrocellulose blotting membrane was used as the solid phase carrier. NDV antigens were directly bound onto the nitrocellulose membrane that was set into a dot blot microfiltration apparatus. Efficiency of the assay was evaluated using known positive and negative NDV sera obtained from chickens. The ability of the assay to detect antibodies 2 days earlier than the standard hemagglutination-inhibition (HI) test was demonstrated on sera collected from chickens experimentally infected with NDV, La Sota strain.

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PubMedDate not supplied

Efficacy of combined killed-in-oil emulsion and live Newcastle disease vaccines in chickens.

Following the introduction of routine vaccination regimes with different types of Newcastle disease (ND) vaccines, the incidence of velogenic viscerotropic Newcastle disease (VVND) in commercial poultry worldwide has declined dramatically. Unfortunately, these vaccination regimes are not feasible in free-range and backyard systems of poultry production practiced in many developing countries. In this study, we sought to develop a single vaccination regime in chickens with ND vaccines to elicit a long-lasting high level of ND virus (NDV) antibodies adequate to protect chickens against ND. The level of antibody response, as measured by the hemagglutination-inhibition (HI) test, and the degree of protection against the virulent strain of NDV were studied in chickens immunized with different vaccines. The vaccines used were: killed-in-oil emulsion (subcutaneous; s.c.) plus live virus (oculanasal; o.n.), given concurrently; experimental vaccine (s.c.) plus live virus (o.n.), given concurrently; killed-in-oil (s.c.); experimental vaccine prepared by homogenizing commercial live vaccine and oil emulsion (s.c.); and live virus (o.n.). The results obtained in this study indicate that concurrent administration of oil emulsion and live NDV vaccines induced the best antibody response, but there was no significant difference in protection among the vaccinated groups.

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