In OvoVaccination with Turkey Herpesvirus Hastens Maturation of Chicken Embryo Immune Responses in Specific-Pathogen-Free Chickens

Abstract

Administration of Marek's disease (MD) vaccines in ovo has become a common practice for the poultry industry. Efficacy of MD vaccines is very high, even though they are administered to chicken embryos that are immunologically immature. We have recently demonstrated that in ovo vaccination with turkey herpesvirus (HVT) results in increased activation of T cells at hatch. Our previous results suggested that in ovo vaccination with HVT might have a positive impact not only on MD protection but also on the overall maturity of the developing immune system of the chicken (Gallus gallus domesticus). The objective of this study was to evaluate the effect of administration of HVT at 18 days of embryonation (ED) on the maturation of the embryo immune system. Four experiments were conducted in Specific-Pathogen-Free Avian Supplies (SPAFAS) chickens to evaluate the effect of administration of HVT at 18 ED on the splenic cell phenotypes at day of age (experiment 1) and on the ability of 1-day-old chickens to respond to various antigens compared with older birds (experiments 2 and 3). In addition, a fourth experiment was conducted to elucidate whether administration of other serotype's MD vaccines (CVI988 and SB-1) at 18 ED had the same effect as HVT on the spleen cell phenotypes at day of age. Our results demonstrated that 1-day-old chickens that had received HVT in ovo (1-day HVT) had higher percentages of CD45+, MHC-I+, CD45+MHC-I+, CD3+, MHC-II+, CD3+MHC-II+, CD4+, CD8+, and CD4+CD8+ cells in the spleen than 1-day-old sham-inoculated chickens (1-day sham). Moreover, spleens of 1-day HVT chickens had greater percentages of CD45+MHC-I+ cells and equal or greater numbers of CD4+CD8- and CD4-CD8+ cells than older unvaccinated chickens. In addition, administration of HVT at 18 ED rendered chicks at hatch more responsive to unrelated antigens such as concavalin A, phytohemagglutinin-L, and keyhole limpet hemocyanin. Administration of MD vaccines of other serotypes had an effect, although less remarkable than HVT, on the spleen cell phenotypes at hatch. Vaccines of all three serotypes resulted in an increased percentage of MHC-I+, CD45-MHC-I+, CD4-CD8+, and CD8+ cells, but only HVT resulted in a higher percentage of CD45+, CD45+MHC-I+, CD3+MHC-II+, and CD4+CD8- cells. Results of this study show that it is possible to hasten maturation of the chicken embryo immune system by administering HVT in ovo and open new avenues to optimize the procedure to improve and strengthen the immunocompetency of commercial chickens at hatch.

In ovodelivery of various biological supplements, vaccines and drugs in poultry: current knowledge

“…Some workers have also reported that improved hatchability and efficient protection is achieved after in ovo vaccination with live‐attenuated H7N2 and H9N2 AI virus vaccines . In ovo vaccination against Marek's disease virus using turkey herpesvirus has been reported to hasten immune system maturation and can result in the production of immunocompetent chicks in a commercial set‐up …”

“…155 In ovo vaccination against Marek's disease virus using turkey herpesvirus has been reported to hasten immune system maturation and can result in the production of immunocompetent chicks in a commercial set-up. 156 Researchers have documented the positive effects of in ovo vaccination with diluent containing commercial coccidiosis vaccine (Inovocox EM1 vaccine) in Ross 708 broilers against coccidiosis by determining an increase in feed intake, BW gain, feed conversion ratio, and reduction in mortality up to the study period of 14 days of post-hatch age. 157 In a separate study, Sokale et al 158 showed the impacts of in ovo injection of a commercial coccidiosis vaccine Inovocox EM1 on the hatchability and hatching quality of Ross × Ross 708 broilers, and no significant negative effect was reported.…”

The effects of in ovo administration of encapsulated Toll-like receptor 21 ligand as an adjuvant with Marek’s disease vaccine

“…Increased IFN-γ expression observed with in ovo HVT vaccination in chickens 16 as well as increased NK like activity observed with HVT vaccination at hatch and post-hatch 17 , 18 revealed that innate responses can be elevated to significant level with appropriate immune modulations 19 . In addition, it has recently been reported that in ovo administration of HVT vaccine accelerates the maturation of the immune system by activation and expansion of T cells at hatch 20 .…”

Evaluation of Factors That Influence Dose Variability of Marek's Disease Vaccines

“…In ovo vaccination hastened the onset of protective immunity [202] and did not negatively impact hatchability [198], was compatible with vaccines all three serotypes [202] and was successful in the face of maternal antibodies [203]. Furthermore, in ovo vaccination with HVT hastens immunocompetence in chickens embryos [204]…”

“…d) HVT, due to its protective synergism with SB-1 [142,143], and with the recombinant fowlpox expressing glycoprotein B (rFPV/gB1) [196] as well as its ability to activate the innate immune system and hasten maturation, is in itself an adjuvant [204]. Plaque assay is the in vitro quantitative assay for determining the vaccine titer [226].…”