Protective immunity induced by co-injection of mixture of Mannan and B-glucan immunostimulant substances with the inactivated Bivalent Al-ND vaccine in broiler chickens

In the present study, the effect of a mixture of some immunostimulant substances on the immune response of broiler chicks to bivalent Al-ND vaccine was determined. Four groups of chicks were used. Group .1 was vaccinated with one dose of Al-ND vaccine and simultaneously injected with the mixture of immunostimulant substances. Group 2 was vaccinated with one dose of the bivalent AI.-ND vaccine. Group 3 was vaccinated with 2 doses of live ND vaccines [Hitchner then Lasota drains] and group 4 was kept none vaccinated control chicb. All birds were monitored weekly for the humoral and cellular immune response then challenged with the virulent NDV at 35 days of age. HI test was used for titration of antibodies for both AIV and NDV, phagocytic activity, Nitric oxide; Lysozyme activity and total antioxidant in serum were used to determine the cellular immune response of the chicks. Protective immunity induced in the vaccinated groups varied. The injected immunostimulant mixture demonstrates its effect on the immune response to the bivalent Al-ND vaccine in group 1 with 100% protection against the challenge NDV. Whereas, 80 and 60% protection were obtained in chicks vaccinated either. with Al-ND vaccine [group 2] or live ND vaccines [group 3]; respectively. The present study reports the effect of injection of some immunostimulant substances in augmentation of the immune response to the inactivated vaccines

Evidence for variant avian leucosis virus in cases of mixed infection with Marek's disease virus

In the present study, we report for the first time in Egypt the evidence for variants of avain leucosis virus subgroup J. ALV-J associated with 2 cases of mixed infection with Marek's disease virus, MDV [one case is associated with tumors and the other, from homogenates of blood and tissues of chicks experienced transient paralysis syndrome of MDV] was detected. The ALV-Js might be variants as indicated by histopathological behaviour; negativity of the ALV-J specific PCR; and sero-logical profile in the flock with mixed infection [tumor-cases of ALV and MDV] and in experimentally-infected chickens with blood and tissue homogenates of other mixed infection case of ALV-J and MDV was detected. Using specific PCR for REV and ALV groups A or B, or C and/ or, D all samples of both mixed infection cases revealed negative results for amplification. However, 28.3% of sera samples collected from chickens with tumor-cases at age of 38 weeks were positive for ALV-J and negative for ALV [groups A and B] by ELISA. Testing of sera collected from the flock with tumor-cases at 45 and 55 weeks of age revealed that 38.2% and 20% of sera were positive for ALV-J and 2.9 and 3% were positive for ALV [groups A and B], respectively. In experimentally-infected chickens with homogenates of blood and spleen, 14.2% of sera were positive to ALV-J and negative for ALV [groups A and B] when tested at 30 weeks post-inoculation. Histopathological examination revealed the occurrence of mixed infection of MDV and ALV-J with unique pathological lesions in eye and liver which were found to have heavily aggregations of myelocytes characteristic to ALV subgroup J

Efficacy of day - old ocular vaccination against very virulent infectious bursal disease virus in commercial broilers

The effect of day old ocular vaccination with live intermediate infectious bursal disease virus [IBDV] vaccine was tested in commercial broiler chicks that have maternally derived antibodies [MDA] against infectious bursal disease virus [IBDV]. Chicks were challenged with very virulent IBDV [vvIBDV] either at 24 days of age after being vaccinated at 1 and / or 14 days or at 31 days of age of those vaccinated at 1 or 14 and /or 21 days. The assessment of protection was determined by measuring, bursa / body weight [B: B] ratio, bursal index [BI], mean severity index [MSI] of bursal lymphoid tissue lesions and mortality rate at 7 days post-challenge [Pch], in addition, antibody response to IBDV at 14 days Pch. Vaccination at 21, 14 and 21 and 1, 14 and 21 days of age protected 100% of vaccinated commercial broiler chickens only against mortality of vvIBDV. However, none of the different vaccination regimes protected commercial broiler chickens neither from bursal atrophy nor bursal lesions. Serum IBDV antibody levels, as monitored by Enzyme-Linked Immunosorbent Assay [ELISA], showed similar rates of decline among non-vaccinated and all the vaccinated groups and by day 35 PV, serum antibody level in non-vaccinated and vaccinated groups were below detectable levels. Results of these studies indicate that IBDV vaccination al one day of age via eye drop doesn't protect against mortality, bursal atrophy and lesions and doesn't cause accelerated IBDV specific MDA. Moreover, the serological examination of optimal vaccination time for each flock is required to control of vvIBDV in me field

Studies on recent outbreaks of infectious laryngotracheitis

Recently, increased incidence of outbreaks of infectious laryngotracheitis [ILT] was observed among chicken flocks in Egypt. These were associated with variable high mortalities. Investigation of 8 such outbreaks revealed that three nonvaccinated replacement layer pullets of 6-8 weeks of age were severely affected with mortality rates of 11-12% up to 40%, while in a 4[th] pullet flock of 24 weeks of age, which was comparatively milder and resulted in only 2% mortality. On the other hand, in four commercial broiler flocks of 5-7 weeks of age with no history of previous vaccination, the disease varied in severity and mortalities [7.6 - 18.0%]. Eight isolates were recovered from these outbreaks and were identified as those of ILTV. Pathogenicity tests for two representative isolates from pullets and broilers were carried out by inoculation of each intratracheally into susceptible chickens of the respective types [egg and meat-type], morbidity and mortality rates were used to calculate an intratracheal pathogenicity index used the same as that described for Newcastle disease virus, in addition to microscopic tracheal lesion scoring as criteria for judging their pathogenicity. Results indicated that both isolates were pathogenic like wild ILT field viruses. Reversed virulence of modified live vaccine viruses was speculated under prevailing conditions of suboptimal management practices, hygiene and biosecurity measures which help spread of infection between flocks, beside the role of latently infected carrier birds and other factors in the epizootiology of the disease, especially in nonvaccinated flocks, were discussed

Administration of non activated infectious bursal disease oil-emulsion vaccine to commercial layer chickens at different ages

Commercial layer chickens of different ages carrying maternal antibody levels to infectious bursal disease [IBD] were inoculated with a full dose a commercial inactivated oil-emulsion IBD vaccine, and then challenged with very virulent IBD virus [vvIBDV] at 7 and 14 days post-vaccination [PV]. The results revealed complete absence of vaccinal protection [0%] one week PV and poor vaccinal protection [10- 50%] two weeks PV, when vaccination adopted weekly during the period from 7 up to 35 days of age. However, survivors during this period showed bursal lesions and significant [P <0.05] bursal atrophy two weeks PV despite vaccinal protection conferred against mortality