ABSTRACT
Recent cases of porcine reproductive and respiratory syndrome virus (PRRSV) infection in United States swine-herds have been associated with high mortality in piglets and severe morbidity in sows. Analysis of the ORF5 gene from such clinical cases revealed a unique restriction fragment polymorphism (RFLP) of 1-7-4. The genome diversity of seventeen of these viruses (81.4% to 99.8% identical; collected 2013-2015) and the pathogenicity of 4 representative viruses were compared to that of SDSU73, a known moderately virulent strain. Recombination analyses revealed genomic breakpoints in structural and nonstructural regions of the genomes with evidence for recombination events between lineages. Pathogenicity varied between the isolates and the patterns were not consistent. IA/2014/NADC34, IA/2013/ISU-1 and IN/2014/ISU-5 caused more severe disease, and IA/2014/ISU-2 did not cause pyrexia and had little effect on pig growth. ORF5 RFLP genotyping was ineffectual in providing insight into isolate pathogenicity and that other parameters of virulence remain to be identified.
Subject(s)
Evolution, Molecular , Genetic Variation , Porcine Reproductive and Respiratory Syndrome/virology , Porcine respiratory and reproductive syndrome virus/genetics , Porcine respiratory and reproductive syndrome virus/pathogenicity , Recombination, Genetic , Viral Envelope Proteins/genetics , Animals , Genotype , Polymorphism, Restriction Fragment Length , Porcine Reproductive and Respiratory Syndrome/epidemiology , Porcine Reproductive and Respiratory Syndrome/pathology , Sequence Analysis, DNA , Swine , United States/epidemiologyABSTRACT
Previously, we have shown that CMV isolated from deer mouse could be used in vivo and in vitro to express Sin Nombre virus (SNV) glycoprotein G1 in deer mice [Rizvanov AA, van Geelen AG, Morzunov S, et al. Generation of a recombinant cytomegalovirus for expression of a hantavirus glycoprotein. J.Virol. 2003;77(22):12203-10]. In this report, we further characterize replication of wild-type (wt) and recombinant Peromyscus CMV (PCMV) in vivo and in vitro using realtime PCR, and infectious center assays. Our findings indicate that both wt PCMV and recombinant PCMV establish persistent infections in P. maniculatus. In addition, we demonstrated that gamma irradiation of PCMV infected mice resulted in reactivation of recombinant PCMV in persistently infected mice.
Subject(s)
Cytomegalovirus/immunology , Orthohantavirus/genetics , Orthohantavirus/immunology , Peromyscus/virology , Viral Envelope Proteins/biosynthesis , Viral Vaccines/immunology , Animals , Cytomegalovirus/genetics , DNA/biosynthesis , DNA/genetics , DNA Replication , Reverse Transcriptase Polymerase Chain Reaction , Vaccines, Synthetic/immunology , Viral Envelope Proteins/genetics , Virus Replication , Whole-Body IrradiationABSTRACT
A cytomegalovirus (CMV) was isolated from its natural host, Peromyscus maniculatus, and was designated Peromyscus CMV (PCMV). A recombinant PCMV was constructed that contained Sin Nombre virus glycoprotein G1 (SNV-G1) fused in frame to the enhanced green fluorescent protein (EGFP) gene inserted into a site homologous to the human CMV UL33 (P33) gene. The recombinant CMV was used for expression and immunization of deer mice against SNV-G1. The results of the study indicate that P. maniculatus could be infected with as few as 10 virus particles of recombinant virus. Challenge of P. maniculatus with either recombinant or wild-type PCMV produced no overt pathology in infected animals. P. maniculatus immunized with recombinant virus developed an antibody response to SNV and EGFP. When rechallenged with recombinant virus, animals exhibited an anamnestic response against SNV. Interestingly, a preexisting immune response against PCMV did not prevent reinfection with recombinant PCMV.