Infectious cDNA clones of porcine reproductive and respiratory syndrome virus and their potential as vaccine vectors

Abstract

Full-length infectious cDNA clones have recently become available for both European and North American genotypes of porcine reproductive and respiratory syndrome virus (PRRSV), and it is now possible to alter the PRRSV genome and create genetically defined mutant viruses. Among many possible applications of the PRRSV infectious cDNA clones, development of genetically modified vaccines is of particular interest. Using infectious clones, the PRRSV genome has been manipulated by changing individual amino acids, deleting coding regions, inserting foreign sequences, and generating arterivirus chimeras. The limited available data suggest that all structural proteins of PRRSV are essential for replication of the virus, and that PRRSV infectivity is relatively intolerant of subtle changes within the structural proteins. The major tasks in PRRSV research are to identify virulence factors and pathogenic mechanisms, and to understand the structure-function relationships of individual viral proteins. Utilizing these infectious clones as tools, a new generation of safe and efficacious PRRS vaccines may be constructed.

Porcine Respiratory and Reproductive Syndrome Virus Variants, Vietnam and China, 2007

“…Whole genome-based phylogenetic relationship also showed that all these viral isolates are grouped into the same subclade in the type II genotype (Figure 2). All of the 2007 strains, together with those Chinese viruses collected in 2006, were found to be similar to 3 Chinese strains reported previously (HB-1, HB-2, and CH-1a) (3,12) and 1 NA-type virulent strain, P129 (8,9).…”

“…Subsequent genomic analysis showed that all the PRRSVs isolated from this outbreak (8) share a unique discontinuous deletion of 30 aa in Nsp2. In previous studies, only 2 virulent NA-type PRRSV strains (P129 and MN184) had been suggested to carry deletions in the Nsp2 protein (different from our 30-aa deletion), a highly variable region that contributes to the virulence and PRRSV genotyping (9,10).…”

Antiviral Regulation in Porcine Monocytic Cells at Different Activation States

“…To potentiate antiviral immunity within the context of the porcine monocytic cell activation paradigm, a molecular tool was needed. One molecular tool that we developed is an IFN-expressing PRRSV infectious cDNA clone (37,52). Using this PRRSV cDNA vector, we have stably expressed immune effectors, including multiple type I IFNs (37).…”

An infectious clone of the highly pathogenic porcine reproductive and respiratory syndrome virus: Topology of glycoprotein 3 (GP3) addressing the intrachain disulfide bonds

“…To rescue infectious viruses vrBJSY07 and vBJSY07, 293T cells were transfected with the in vitrotranscribed RNA. We chose 293T cells to assemble the first passage virions for their high efficiency of RNA transfection; higher than BHK21 cells which had been successfully used in previous reports [22,27,30]. The harvested cell medium containing the rescued virus vrBJSY07 and vBJSY07 particles were then each transferred to PRRSV permissible cells.…”

“…This method is very powerful for the analysis of gene expression [16], replication [17], function of viral proteins [18], recombination of RNA viruses, and pathogenesis by mutating individual amino acids [19], deleting coding regions [17], inserting foreign sequences [20], and generating chimeric virions [21]. It can also potentially be used to develop new genetically-modified vaccines [22]. Thus, establishing an infectious viral genomic clone would be extremely useful to investigate the biology of hpPRRSV.…”