Chimeric porcine reproductive and respiratory syndrome virus containing shuffled multiple envelope genes confers cross-protection in pigs

Abstract

The extensive genetic diversity of porcine reproductive and respiratory syndrome virus (PRRSV) strains is a major obstacle for vaccine development. We previously demonstrated that chimeric PRRSVs in which a single envelope gene (ORF3, ORF4, ORF5 or ORF6) was shuffled via DNA shuffling had an improved heterologous cross-neutralizing ability. In this study, we incorporate all of the individually-shuffled envelope genes together in different combinations into an infectious clone backbone of PRRSV MLV Fostera(®) PRRS. Five viable progeny chimeric viruses were rescued, and their growth characteristics were characterized in vitro. In a pilot pig study, two chimeric viruses (FV-SPDS-VR2,FV-SPDS-VR5) were found to induce cross-neutralizing antibodies against heterologous strains. A subsequent vaccination/challenge study in 72 pigs revealed that chimeric virus FV-SPDS-VR2 and parental virus conferred partial cross-protection when challenged with heterologous strains NADC20 or MN184B. The results have important implications for future development of an effective PRRSV vaccine that confers heterologous protection.

Evaluation of the Cross-Protective Efficacy of a Chimeric Porcine Reproductive and Respiratory Syndrome Virus Constructed Based on Two Field Strains

“…Moreover, the presence of single, strain-specific neutralizing epitopes in a PRRSV might limit its cross-protection against genetically diverse PRRSVs [31]. Another study demonstrated the construction of structural genes-shuffled chimeric PRRSVs, and one chimera and its parental strain were observed to offer partial cross-protection in pigs [32]. Although the random shuffling of structural genes increases the heterogeneity of neutralizing epitopes in the resulting PRRSV construct, the significance of structural proteins from different PRRSV strains and their proper frame/order cannot be neglected when constructing an organized vaccine platform.…”

The non-structural protein Nsp2TF of porcine reproductive and respiratory syndrome virus down-regulates the expression of Swine Leukocyte Antigen class I

“…Fresh BHK-21 cells were transfected with each plasmid DNA using Lipotectamine LTX and Plus Reagent kit (Invitrogen) as described previously (Tian et al, 2015).. At 48 h post-transfection, cell culture supernatants were harvested and serially passaged onto MARC-145 cells. Transfected or infected cells were examined by indirect immunofluorescence assay (IFA) using PRRSV monoclonal antibody SDOW17.…”

“…To investigate the growth properties of the mutant viruses in MARC-145, a multiple-step growth curve analysis was conducted as described previously (Tian et al, 2015). Briefly, MARC-145 cells in 12-well plates were infected with each of the mutant viruses as well as parental viruses (passage P2) at a low MOI of 0.1.…”

Broad Protection of Pigs against Heterologous PRRSV Strains by a GP5-Mosaic DNA Vaccine Prime/GP5-Mosaic rVaccinia (VACV) Vaccine Boost

“…The diversity among PRRSV strains is as high as, or may even surpass that of, HIV. Recently, several vaccine candidates, including a synthetic consensus PRRSV strain [27], a chimeric PRRSV strain containing multiple ORFs DNA shuffled [46][47][48] and an intranasal live virus vaccine with adjuvant [49] induced various levels of heterologous protection in pigs. We have developed GP5-Mosaic vaccines that incorporate sequences derived from naturally circulating viruses.…”