Replication of recombinant herpesvirus of turkey expressing genes of infectious laryngotracheitis virus in specific pathogen free and broiler chickens followingin ovoand subcutaneous vaccination

Abstract

Replication of a recombinant herpesvirus of turkey vaccine expressing infectious laryngotracheitis virus genes (rHVT-LT) was evaluated in specific pathogen free (SPF) and commercial broiler chickens after various vaccination protocols (amniotic route at embryonation day [ED] 18; intra-embryonic route at ED 19; and subcutaneous at 1 day of age [s.c.]). Three experiments were conducted: in the first experiment, replication of rHVT-LT vaccine was chronologically evaluated and compared with the replication of herpesvirus of turkey (HVT) in SPF chickens; in the second experiment, the effect of different in ovo vaccination procedures on rHVT-LT vaccine replication was evaluated in SPF chickens; and in the third experiment, the effect of different in ovo vaccination procedures on rHVT-LT vaccine replication was evaluated in commercial broiler chickens with maternal antibodies against HVT and infectious laryngotracheitis virus (LTV). rHVT-LT vaccine replicated in chickens after in ovo (ED 18 and ED 19) or s.c. administration at a similar level. In vivo replication of rHVT-LT vaccine was slower than HVT vaccine. However, in vivo both rHVT-LT and HVT vaccines replicated at similar levels. Both vaccines were consistently detected in the spleen and feather pulp and at lower frequency in the lung. The frequency of samples with detectable levels of rHVT-LT DNA was lower in broiler chickens than in SPF chickens, probably due to interactions with maternal antibodies. Differences between SPF chickens and broiler chickens were found also in the transcription of the LTV glycoprotein I gene (gI). In SPF chickens, in ovo inoculation resulted in a higher number of spleen samples with detectable gI transcripts than s.c. inoculation. In broiler chickens, however, no differences in the level of gI transcripts in spleen samples were found between chickens vaccinated in ovo and those vaccinated by the s.c. route. Transcription of LTV gI gene in lung samples was very low in both SPF and broiler chickens. Further studies to evaluate the mucosal immune response elicited by rHVT-LT in chicken with and without maternal antibodies are warranted.

Les herpèsvirus des oiseaux

“…L'emploi d'un aérosol présente aussi l'inconvénient de réactions indésirables (vaccin insuffisamment atténué ou gouttelettes de trop petite taille atteignant l'appareil respiratoire profond). Aussi des vaccins recombinants utilisant comme vecteur la souche virale MeHV-1 permettant-ils de lutter en même temps contre la MM, ont été développés pour un emploi in ovo ou par la voie sous-cutanée (Johnson et al 2010 ;Gimeno et al 2011).…”

An Attenuated Duck Plague Virus (DPV) Vaccine Induces both Systemic and Mucosal Immune Responses To Protect Ducks against Virulent DPV Infection

“…Student's t test was used to analyze the statistical differences in T lymphocyte and Ig antibody responses between vaccine and control groups. SPSS 16.0 was applied to analyze the protection assay, and statistical analysis of mortality was analyzed by the log rank and chisquare tests. Results were considered statistically significant if P values were Ͻ0.05 or Ͻ0.01 for comparisons with the nonimmunized group.…”

“…The route of vaccine administration is an important factor for vaccination efficiency (15,16). The kinetics of the attenuated DPV vaccine strain CHa determined that subcutaneous administration had a larger effect on the vaccine virus distribution in tissue than the oral and nasal routes of administration did (17).…”

Quantification of rHVT-F genome load in feather follicles by specific real-time qPCR as an indicator of NDV-specific humoral immunity induced by day-old vaccination in SPF chickens

“…According to its useful characteristics previously reviewed (Schat & Nair, 2008), the HVT, mainly the FC126 strain, has been widely and successfully used as vector for recombinant bivalent vaccine (rHVT) to protect chickens against ND (Reddy et al, 1996;Rauw et al, 2010;Palya et al, 2012Palya et al, , 2014Esaki et al, 2013), infectious bursal disease virus (Darteil et al, 1995;Tsukamoto et al, 2002;Bublot et al, 2007;Le Gros et al, 2009;Perozo et al, 2009), avian influenza (Gao et al, 2011;Rauw et al, 2012;Soejoedono et al, 2012) and infectious laryngotracheitis (Johnson et al, 2010;Gimeno et al, 2011a). This success is related to (i) its safety, (ii) the possibility of an early administration, which could be in ovo or at day-old without adverse effects on hatchability or survival of vaccinated chicks, (iii) its low sensitivity to interference with maternally derived antibody (MDA) when injected in the cell-associated form and (iv) its potential for long-term induction of protective immunity against pathogens.…”

“…HVT is non-oncogenic for chickens and has been used for a long time as live vaccine in vaccination programmes, alone or in combination with other MDV vaccine strains (like Rispens or SB-1), for protection against MD. Quantitative real-time polymerase chain reaction (real-time qPCR) specific to HVT has been developed for monitoring HVT genome load in blood (Gimeno et al, 2008(Gimeno et al, , 2011bCortes et al, 2011), buffy coat (Gimeno et al, 2008), spleen (Abdul-Careem et al, 2008a;Gimeno et al, 2011a), feathers follicles (FF; AbdulCareem et al, 2008b;Cortes et al, 2011;Gimeno et al, 2011a, b), lung (Haq et al, 2010;Gimeno et al, 2011a) and dust (Islam & Walkden-Brown, 2007) after experimental in ovo or day-old MD vaccination of specific pathogen free (SPF) chickens with HVT vaccine.…”