ABSTRACT
Recombinant baculoviruses containing the fusion (F) and hemagglutinin-neuraminidase (HN) glycoprotein gene of the viscerotropic velogenic (vv) Newcastle disease virus (NDV) isolate, Kr-005/00, and a lentogenic La Sota strain of the NDV were constructed in an attempt to develop an effective subunit vaccine to the recent epizootic vvNDV. The level of protection was determined by evaluating the clinical signs, mortality, and virus shedding from the oropharynx and cloaca of chickens after a challenge with vvNDV Kr-005/00. The recombinant ND F (rND F) and recombinant HN (rND HN) glycoproteins derived from the velogenic strain provided good protection against the clinical signs and mortality, showing a 0.00 PI value and 100% protection after a booster immunization. On the other hand, the combined rND F + HN glycoprotein derived from the velogenic strain induced complete protection (0.00 PI value and 100% protection) and significantly reduced the amount of virus shedding even after a single immunization. The rND F and rND HN glycoproteins derived from the velogenic strain had a slightly, but not significantly, greater protective effect than the lentogenic strain. These results suggest that the combined rND F + HN glycoprotein derived from vvNDV can be an ideal subunit marker vaccine candidate in chickens in a future ND eradication program.
Subject(s)
Animals , Baculoviridae/genetics , Chickens/virology , DNA Primers , Gene Amplification , HN Protein/genetics , Korea , Marek Disease/immunology , Newcastle Disease/immunology , Spodoptera/virology , Vaccines, Synthetic/genetics , Viral Vaccines/geneticsABSTRACT
In this study, we investigated the effects of T-cell suppression on the pathogenesis of subgroup J avian leukosis virus (ALV-J). Chickens were treated with cyclosporin A (CSP) 50 mg/Kg body weight or a corresponding volume of olive oil per every three days after hatching until the end of experiment. Some of the chickens from each treatment group were infected with an isolate of ALV-J, ADOL-7501, at 2 weeks of age. The effects of viral infection were compared to uninfected birds in same treatment group. Intramuscular injection of CSP induced significant T-cell specific immunosuppression determined by decreased cutaneous basophilic hypersensitivity response and decreased lymphocyte mitogenic activity using concanavalin A. Most of the chickens examined had Marek's disease virus infection prior to 3 weeks of age. The percentage of antibody-positive birds and antibody titers were similar in infected chickens between both treatment groups. The ratio of viremic chickens was significantly higher in CSP treated group than that of the Oil treated group. Microscopically, one CSP treated chicken had a nephroblastoma at 10 weeks post infection. At 7 and 10 weeks post-infection, more chickens had myeloid cell infiltrations in multiple organs including heart, liver and occasionally lung. Expression of ALV-J viral antigen determined by immunohistochemical staining was significantly higher in CSP treated chickens than Oil treated chickens at 10 weeks post-infection. This study indicated that chemically-induced T-cell suppression may enhance pathogenicity of the AVL-J virus in broilers.
Subject(s)
Animals , Antibodies, Viral/blood , Avian Leukosis/immunology , Avian Leukosis Virus/genetics , Body Weight , Chickens , Cyclosporine/pharmacology , Dermatitis, Contact/immunology , Flow Cytometry , Immunocompromised Host , Immunohistochemistry/veterinary , Immunophenotyping , Immunosuppressive Agents/pharmacology , Lymphocyte Activation/immunology , Marek Disease/immunology , RNA, Viral/chemistry , Reverse Transcriptase Polymerase Chain Reaction/veterinary , T-Lymphocytes/immunology , Viremia/veterinaryABSTRACT
Dinitrofluorobenzene (DNFB) contact-sensitivity test and leucocyte adherence inhibition (LAI) test were performed in this study as in vivo and in vitro tests to measure the cell-mediated immunity (CMI) in chickens subjected to stimulation of reticuloendothelial (RE) system, depletion of RE system and other experimental groups after being challenged with Marek's disease (MD) virus. It was found that CMI was lower in the birds with depleted RE system and infected control birds, whereas CMI was higher in the birds with activated RE system and vaccinated birds as revealed by DNFB contact-sensitivity test. In cases of LAI test, the number of LAI-positive birds were highest in the chicks with depleted RE system particularly in 3rd and 4th month of age, when the incidence of MD was also maximum.
Subject(s)
Animals , Chickens , Dinitrofluorobenzene/immunology , Immunity, Cellular , Leukocyte Adherence Inhibition Test , Marek Disease/immunology , Mononuclear Phagocyte System/immunologyABSTRACT
An enzyme treated preparation of Mycobacterium phlei (NSI), induced strong cell mediated immune response (CMIR) against specific as well as against nonspecific oncogenic Marek's disease (MDV) in birds, as evinced by Lymphocyte migration inhibition, (LMIT) lymphocyte transformation test (LT) and Lymphokine (Lymphocyte migration inhibition factor) LyIF assay. Maximum CMIR could be observed towards third week post inoculation. All the three tests exhibited a positive correlation. Such phenomenon of CMIR induction by NSI, nonspecifically to unrelated viral/cancerous diseases (MD) in birds generates hopes for immunoprevention of these maladies by utilizing such phenomenon.