Construction of chimeric bovine viral diarrhea viruses containing glycoprotein E rns of heterologous pestiviruses and evaluation of the chimeras as potential marker vaccines against BVDV.

Bovine viral diarrhea virus (BVDV) infections are enzootic in the cattle population and continue to cause significant economic losses to the beef and dairy industries worldwide. Extent of the damages has stimulated increasing interest in control programs directed at eradicating BVDV infections. Use of a BVDV marker vaccine would facilitate eradication efforts as a negatively marked vaccine would enable differentiation of infected from vaccinated animals (DIVA).

A brief review of CD163 and its role in PRRSV infection.

Porcine reproductive and respiratory syndrome virus (PRRSV) infects fully differentiated cells of the monocyte/macrophage lineage. Recently, CD163 was shown to be a cellular receptor capable of mediating infection of otherwise PRRSV non-permissive cell lines. CD163 is a macrophage differentiation antigen belonging to the scavenger receptor cysteine-rich (SRCR) family of membrane proteins.

Porcine reproductive and respiratory syndrome virus as a vector: immunogenicity of green fluorescent protein and porcine circovirus type 2 capsid expressed from dedicated subgenomic RNAs.

Porcine reproductive and respiratory syndrome virus (PRRSV) is the causative agent of PRRS, which is characterized by late-term abortions in sows and respiratory disease in young pigs. Using an infectious cDNA clone of North American PRRSV strain P129, the viral genome was engineered to transcribe an additional subgenomic RNA initiating between non-structural and structural genes. Two unique restriction sites and a copy of the transcription regulatory sequence for ORF6 (TRS6) were inserted between ORFs 1b and 2a, yielding a general purpose expression vector.

Functional mapping of the porcine reproductive and respiratory syndrome virus capsid protein nuclear localization signal and its pathogenic association.

PRRSV (porcine reproductive and respiratory syndrome virus) nucleocapsid (N) protein is the most abundant structural protein of the virus. During infection, the N protein is specifically localized to the nucleus and nucleolus in addition to its normal cytoplasmic distribution. Previously, a nuclear localization signal (NLS, 41-PGKK(N/S)KKKN)-null mutant virus (41-PGGGNKKKN) showed reduced viremia and increased production of neutralizing antibodies in infected pigs.

CD163 expression confers susceptibility to porcine reproductive and respiratory syndrome viruses.

Direct functional screening of a cDNA expression library derived from primary porcine alveolar macrophages (PAM) revealed that CD163 is capable of conferring a porcine reproductive and respiratory syndrome virus (PRRSV)-permissive phenotype when introduced into nonpermissive cells. Transient-transfection experiments showed that full-length CD163 cDNAs from PAM, human U937 cells (histiocytic lymphoma), African green monkey kidney cells (MARC-145 and Vero), primary mouse peritoneal macrophages, and canine DH82 (histocytosis) cells encode functional virus receptors. In contrast, CD163 splice variants without the C-terminal transmembrane anchor domain do not provide PRRSV receptor function.

Mutations within the nuclear localization signal of the porcine reproductive and respiratory syndrome virus nucleocapsid protein attenuate virus replication.

Porcine reproductive and respiratory syndrome virus (PRRSV) is an RNA virus replicating in the cytoplasm, but the nucleocapsid (N) protein is specifically localized to the nucleus and nucleolus in virus-infected cells. A 'pat7' motif of 41-PGKK(N/S)KK has previously been identified in the N protein as the functional nuclear localization signal (NLS); however, the biological consequences of N protein nuclear localization are unknown. In the present study, the role of N protein nuclear localization during infection was investigated in pigs using an NLS-null mutant virus.

A DNA-launched reverse genetics system for porcine reproductive and respiratory syndrome virus reveals that homodimerization of the nucleocapsid protein is essential for virus infectivity.

Reverse genetic systems were developed for a highly virulent 'atypical' porcine reproductive and respiratory syndrome virus (PRRSV). The full-length genome of 15395 nucleotides was assembled as a single cDNA clone and placed under either the prokaryotic T7 or eukaryotic CMV promoter. Transfection of cells with the RNA transcripts or the DNA clone induced cytopathic effects and produced infectious progeny.

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

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.