Analysis of immunogenicity of minor envelope protein GP3 of porcine reproductive and respiratory syndrome virus in mice

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most economically significant viral diseases in swine industry. Though the minor envelope protein GP3 is associated with protective immunity, its immunogenicity and protective mechanism are poorly known. In this study, two recombinant adenoviruses, rAd-GP3 expressing complete GP3 and rAd-tGP3 expressing truncated GP3 in which aa2-64 were deleted, were constructed and the immunogenicity were tested in a mouse model. Four groups of BALB/c mice were immunized subcutaneously twice at 2-week internals with the recombinants rAd-GP3 and rAd-tGP3 or with wild type adenovirus (wtAd) and PBS as control. The results showed that the mice immunized with recombinant adenoviruses developed PRRSV-specific neutralizing antibodies and cellular immune response, including T-cell proliferation responses and cytotoxic T responses, by 2 weeks post-primary immunization. Moreover, the levels of immune responses of mice immunized with rAd-tGP3 were significantly higher than that of mice with rAd-GP3. It indicated that the first 64aa fragment of GP3 might affect the conformation of the antigen structures of GP3 protein. GP3 protein should be one of candidate molecules for developing a new safer effective vaccine.

A Novel Isolate with Deletion inGP3Gene of Porcine Reproductive and Respiratory Syndrome Virus from Mid-Eastern China

“…The 254-AA GP3 protein is encoded by ORF3 and has a molecular mass of approximately 42 kDa [33, 34]. The GP3 protein is one of the most variable structural proteins among the PRRSVs, with only 54% to 60% AA sequence identity shared between the Type-1 and Type-2 strains [24, 35].…”

Porcine Reproductive and Respiratory Syndrome Virus Vaccines: Current Status and Strategies to a Universal Vaccine

“…After mice immunized with the recombinants rAd-GP3 and rAD-tGP3, PRRSV-specific neutralization antibodies, T-cell proliferation responses and cytotoxic T responses were observed, although the production of neutralizing antibodies was tardy. Interestingly, the immune response elicited by rAd-tGP3 was stronger than that of rAd-GP3 (Jiang et al, 2007). The mechanism underlying this phenomenon remains unclear, but it might suggest some adverse factors lie within the deleted sequence of GP3.…”

“…The authors also found that ORF7 gene product (N protein) is the most immunogenic protein of PRRSV, but the antibodies induced in sows are non-protective and may even interfere with protection (Plana Duran et al, 1997). The immunogenicity of GP3 was further characterized by using two recombinant adenoviruses (rAd), rAd-GP3 expressing complete GP3 and rAD-tGP3 expressing truncated GP3 in which amino acids 2-64 were deleted (Jiang et al, 2007). After mice immunized with the recombinants rAd-GP3 and rAD-tGP3, PRRSV-specific neutralization antibodies, T-cell proliferation responses and cytotoxic T responses were observed, although the production of neutralizing antibodies was tardy.…”

Immunogenic and protective properties of GP5 and M structural proteins of porcine reproductive and respiratory syndrome virus expressed from replicating but nondisseminating adenovectors

“…Most of these strategies rely on the use of DNA-based vaccines [21-26], transgenic plants [27,28], bacterial vectors [29-31], or viral vectors. Among the viral vectors used are non-replicative human [17,32-39] and canine adenoviruses [40], transmissible gastroenteritis virus [41], the modified strain of vaccinia virus [16], pseudorabies virus [15,42] and fowlpox virus [43]. Approximately half of these immunization studies were conducted in pigs that were then exposed to an experimental challenge, but only a few compared their efficacy with commercially-available vaccines [15,23,42].…”