Evaluation of the Protection Efficacy of a Serotype 1 Marek's Disease Virus-Vectored Bivalent Vaccine Against Infectious Laryngotracheitis and Marek's Disease

Abstract

Laryngotracheitis (LT) is a highly contagious respiratory disease of chickens that produces significant economic losses to the poultry industry. Traditionally, LT has been controlled by administration of modified live vaccines. In recent years, the use of recombinant DNA-derived vaccines using turkey herpesvirus (HVT) and fowlpox virus has expanded, as they protect not only against the vector used but also against LT. However, HVT-based vaccines confer limited protection against challenge, with emergent very virulent plus Marek's disease virus (vv+MDV). Serotype 1 vaccines have been proven to be the most efficient against vv+MDV. In particular, deletion of oncogene MEQ from the oncogenic vvMDV strain Md5 (BACδMEQ) resulted in a very efficient vaccine against vv+MDV. In this work, we have developed two recombinant vaccines against MD and LT by using BACδMEQ as a vector that carries either the LT virus (LTV) gene glycoprotein B (gB; BACΔMEQ-gB) or LTV gene glycoprotein J (gJ; BACδMEQ-gJ). We have evaluated the protection that these recombinant vaccines confer against MD and LT challenge when administered alone or in combination. Our results demonstrated that both bivalent vaccines (BACΔMEQ-gB and BACδMEQ-gJ) replicated in chickens and were safe to use in commercial meat-type chickens bearing maternal antibodies against MDV. BACΔMEQ-gB protected as well as a commercial recombinant (r)HVT-LT vaccine against challenge with LTV. However, BACδMEQ-gJ did not protect adequately against LT challenge or increase protection conferred by BACΔMEQ-gB when administered in combination. On the other hand, both BACΔMEQ-gB and BACδMEQ-gJ, administered alone or in combination, protected better against an early challenge with vv+MDV strain 648A than commercial strains of rHVT-LT or CVI988. Our results open a new avenue in the development of recombinant vaccines by using serotype 1 MDV as vectors.

Vaccines against Major Poultry Viral Diseases: Strategies to Improve the Breadth and Protective Efficacy

“…Both BACDMEQ-gB and BACDMEQ-gJ were found to induce rapid immunity against an early vv + MDV challenge to surpass the protection provided by the GaHV-1 HVT vaccine and the serotype 1 attenuated CVI 988 vaccine. The BACDMEQ vector was also effective in preventing MD-induced tumors and immunosuppression [129].…”

“…A recombinant HVT-ILT administered in ovo was however ineffective at breaking the chain of viral transmission [130], but vaccination with eye drops was successful in stimulating the conjunctiva-associated lymphoid tissues (CALT) and the Harderian gland (HG) to provide immunity against ILT [131]. A comprehensive list of registered and experimental vaccines against ILTV has been previously reviewed [129].…”

Infectious laryngotracheitis: Etiology, epidemiology, pathobiology, and advances in diagnosis and control – a comprehensive review

“…The isolate was suggested to be a recombinant of vaccine strain and another recombinant virus (Sabir et al 2020). To overcome the limitations and biosafety concerns of conventional vaccines, recombinant vaccines such as FPV vector vaccine expressing glycoprotein B and UL32 genes of ILTV(McGeoch et al 2006), two HVT vector vaccines, one containing ILTV glycoproteins I and D, and another containing ILTV glycoprotein B (Esaki et al 2013), LaSota strain of Newcastle diseases virus (NDV) that expresses ILTV glycoproteins (Kanabagatte Basavarajappa et al 2014;Zhao et al 2014), modified very virulent Marek's disease virus (vvMDV) that express ILTV glycoproteins (Gimeno et al 2015) and recombinant vaccines expressing different ILTV glycoproteins including gB, gC, gD, gG, gI, gJ, TK, UL0, UL32, and UL47 (Vagnozzi et al 2012;Yu et al 2017) were introduced and evaluated. NDV vector expressing gD of ILTV protected birds against both ILT and ND.…”

“…The advantages of these recombinant vaccines are lack of transmission, the absence of reversion to a virulent form, and lack of latency (Johnson et al 2010;Zhao et al 2014). Utilizing a bacterial artificial chromosome (BAC), genes encoding glycoprotein B (gB) or glycoprotein J (gJ) of ILTV were introduced into meq gene deleted very virulent MDV (vvMDV) to create the BACDMEQ-gB and BACDMEQ-gJ recombinant strains, and the resulted BACDMEQ-gB recombinant had conferred immunity after subcutaneous vaccination at day one after hatch which was comparable to commercial ILT-HVT vectored vaccine (Gimeno et al 2015;Garc ıa and Zavala 2019). A study was conducted using the recombinant herpesvirus of turkey based ILT vaccine rHVT-LT and CEO ILT vaccine to know the effect of combined vaccine, to know the effect of rHVT-LT on CEO vaccine and protective efficacy of the vaccine.…”

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

“…A vaccine using serotype 1 vvMDV strain Md5 with the meq oncogene deleted protects against both tumors and late immunosuppression induced by vv+MDV [48,118,192,193]. Furthermore, it has been used to develop vector vaccines by inserting the glycoprotein B of the ILTV [194]. The use of fowlpox as a vector with the insert of the MDV gB has been developed and is licensed in the USA [159,195,196].…”