Live Fowlpox Research Articles

The co-administration of live fowlpox and Newcastle disease vaccines by non-invasive routes to chickens reared by smallholders in Tanzania and Nepal

The co-administration of commercial live fowlpox (FP) and Newcastle disease (ND) vaccines when given by non-invasive (needle-free) routes was demonstrated to be safe and to elicit immunity in two field studies, one in Tanzania the other in Nepal. Both studies were of a cluster-randomised controlled design in which birds were randomly assigned to one of five treatment groups: (i) administration with FP vaccine alone (feather follicle), (ii) administration with ND vaccine alone (eye-drop), (iii) concurrent administration of FP (feather follicle) and ND (eye-drop) vaccines, (iv) concurrent administration of FP (wing-web) and ND (eye-drop) vaccines, and (v) unvaccinated, acting as environmental sentinels. Data from a total of 1167 birds from seven villages in Hanang District of Tanzania together with 1037 birds from eleven villages in Dhading District of Nepal were collected over a period of 21 and 28 days, respectively. Immune responses to FP vaccination were evaluated by local take reactions, while those to ND vaccination were evaluated serologically by haemagglutination inhibition test. The two studies demonstrated that the concurrent vaccination of free-range, indigenous breeds of chicken with live FP and ND vaccines, both administered by non-invasive routes, was safe and induced immunity against FP and ND that were non-inferior to the administration of FP and ND vaccines alone. These findings are important to appropriately trained small-scale backyard poultry farmers as well as to paraprofessionals and community health workers helping to increase vaccine uptake and the control of both FP and ND in low- to middle-income countries.

Construction of chicken infectious anemia virus infectious clone and study on its pathogenicity.

Chicken infectious anemia virus (CIAV) can be transmitted through contaminated live poultry vaccine. However, the pathogenicity of contaminated CIAV strains is rarely reported. Previously, the chickens showed the typical symptoms of anemia after using the attenuated live fowl pox virus (FPV) vaccine. Therefore, exogenous CIAV contamination was suspected. We detected anti-CIAV antibodies in SPF chicks vaccinated with the FPV vaccine. CIAV contamination was confirmed in the FPV vaccine, and the CIAV strain was named JS2020-FPV. This study aims to rescue JS2020-FPV by reverse genetic assays and investigate its pathogenicity. Firstly, double-copies infectious clone of JS2020-FPV was constructed. For the pathogenicity study, infectious clone of JS2020-FPV was used to inoculate 1-day-old SPF chicks. The typical symptoms of anemia were observed in the JS2020-PFV group 14 days post inoculation. The hematocrit and body weight of chicks in the JS2020-PFV group were significantly lower than those in the mock group. Notably, the thymus development index and antibody levels of NDV were lower in chicks in the JS2020-PFV group than those in the mock group. Different degrees of apoptosis of MSB1 and DF-1 were observed after inoculated with the JS2020-FPV VP3 recombinant fusion protein expressed by E. coli system, indicating that VP3 induced apoptosis in the transformed cells. Overall, the pathogenicity of the CIAV detected in the contaminated vaccine was confirmed by inoculating SPF chicks with the double-copies infectious DNA clone in this study. Our findings indicate that the dangers of vaccine contamination cannot be ignored.

Protective immune response of chickens to oral vaccination with thermostable live Fowlpox virus vaccine (strain TPV-1) coated on oiled rice

The objective of the present study was to develop and evaluate a local vaccine (strain TPV-1) against Fowl pox (FP) in chickens. Two separate groups of chickens were vaccinated with FP vaccine through oral (coated on oiled rice) and wing web stab routes, respectively. The results showed that the haemagglutination-inhibition (HI) antibody titres in both vaccinated groups were comparable and significantly higher (P < 0.05) than the control chickens. It was further revealed that 14 days after vaccination HI GMT of > or =2 log(2) was recorded in chickens vaccinated by oral and wing web stab routes whereas 35 days after vaccination the HI antibody titres reached 5.6 log(2) and 6.3 log(2), respectively. Moreover, in both groups the birds showed 100% protection against challenge virus at 35 days after vaccination. The findings from the present study have shown that oral route is equally effective as wing web stab route for vaccination of chickens against FP. However, the oral route can be used in mass vaccination of birds thus avoid catching individual birds for vaccination. It was noteworthy that strain TPV-1 virus could be propagated by a simple allantoic cavity inoculation and harvesting of allantoic fluid where it survived exposure at 57 degrees C for 2 hours. If the oral vaccination technique is optimized it may be used in controlling FP in scavenging and feral chickens. In conclusion, the present study has shown that FP vaccine (strain TPV-1) was safe, thermostable, immunogenic and efficacious in vaccinated chickens.

Protective effect of avian myelomonocytic growth factor in infection with Marek's disease virus.

Marek's disease virus (MDV) is a herpesvirus that induces T lymphomas in chickens. The aim of this study was to assess the role of the macrophage activator chicken myelomonocytic growth factor (cMGF) in controlling MDV infection. B13/B13 chickens, which are highly susceptible to MD, were either treated with cMGF delivered via a live fowlpox virus (fp/cMGF) or treated with the parent vector (fp/M3) or were left as untreated controls. Seven days later, when challenged with the very virulent RB-1B strain of MDV, the spleens of chickens treated with fp/cMGF showed increased expression of the inducible nitric oxide synthase (iNOS) gene compared to those of control chickens and fp/M3-treated chickens. Increased iNOS gene expression was also accompanied by greater induction of gamma interferon and macrophage inflammatory protein (K203) gene expression, both possible activators of iNOS. fp/cMGF treatment also increased the number of monocytes and systemic NO production in contrast to fp/M3 treatment. Even though cMGF treatment was unable to prevent death for the chickens, it did prolong their survival time, and viremia and tumor incidence were greatly reduced. In addition, cMGF treatment improved the partial protection induced by vaccination with HVT (herpesvirus isolated from turkeys) against RB-1B, preventing 100% mortality (versus 66% with vaccination alone) and greatly reducing tumor development. Treatment with fp/M3 did not have such effects. These results suggest that cMGF may play multiple roles in protection against MD. First, it may enhance the innate immune response by increasing the number and activity of monocytes and macrophages, resulting in increased NO production. Second, it may enhance the acquired immune response, indicated by its ability to enhance vaccine efficacy.

Vaccination of chickens with live fowl pox (FP) vaccine in oil.

Live fowl pox (FP) vaccine was adjuvanted in oil just prior to the subcutaneous (SC) vaccination of one day old chicks and adult chickens. The birds were challenged by the wing web (WW) method and absence of "takes" were considered as protection. On 21 day post challenge, 90%-100% of the chicks or chickens were protected while on day 9 post challenge 60% were protected. Full protection of the live-in-oil adjuvanted vaccine is probably somewhat delayed as compared to protection endowed by the liquid vaccine. Incorporation of live FP vaccine in two different kinds of commercial Newcastle disease (ND) killed vaccine in oil, was shown to endow full protection following SC administration.

Persistence of Maternally-Derived Antibody in Selected Group of Chicks to Fowl Pox Virus

The investigation was conducted to determine the persistence of maternally derived antibody as well as its influence on vaccination programme against fowl pox infection. A total of 60-day-old chicks divided into four groups such as A, B, C, D. Chicks of Group A and B were used for the detection of persistence of maternally derived antibody which are originated from fowl pox virus-vaccinated and non-vaccinated parent stock respectively. For the detection of antibody level after vaccination with live fowl pox and pigeon pox virus vaccine following two vaccination schedules, chicks of group C and D were subdivided into group C1, C2 and D1, D2 originating from fowl pox virus vaccinated and non-vaccinated parent stock. It is found that maternally derived antibody passed over from the parents to progeny chicks and remains protective level for the chick of group A until day 4 of age and the chicks of group B which are originated from non-vaccinated parent stock remains protective level only at day 1. Chicks of subgroup C2 and D2 produce higher antibody titre, which were boosted at 15 days interval. Frequent out breaks of fowl pox infection in chicks of Bangladesh either from fowl pox virus-vaccinated and non-vaccinated origin may be avoided by vaccination with pigeon pox virus vaccine at day 5 followed by a secondary vaccination with fowl pox virus vaccine at day 21. Keywords: Maternally-derived antibody (MDA); Chicks; Fowl pox (FP); Fowl pox virus (FPV)DOI: http://dx.doi.org/10.3329/bjm.v25i1.4858 Bangladesh J Microbiol, Volume 25, Number 1, June 2008, pp 57-59

Further evidence of a relationship between live fowl pox virus and parthenogenesis in turkey eggs.

The level of parthenogenesis was determined in unfertilized eggs of 2 similar groups of unselected Beltsville Small White turkeys. Birds of one group were re-vaccinated for fowl pox (live virus) at approximately 36 weeks of age. The others serving as controls had received only one vaccination when 6-8 weeks of age. The treated group produced 1091 eggs and the controls 1099 eggs during the 90-day test period. Approximately 28% of the eggs from the treated group and about 17% of the control group underwent some degree of parthenogenetic development during 10 days of incubation. Twenty-four embryos (2.7%) were encountered in eggs of the treated hens as compared to 4 (0.36%) in eggs of the controls.