Although North American and European serotypes of porcine reproductive and respiratory syndrome virus (PRRSV) are recognized, only the genome of the European Lelystad strain (LV) has been sequenced completely. Here, the genome of the pathogenic North American PRRSV isolate 16244B has been sequenced and compared with LV. The genomic organization of 16244B was the same as LV but with only 63n4 % nucleotide identity. The 189 nucleotide 5h non-coding region (NCR) of 16244B was distinct from the LV NCR, with good conservation (83 %) only over a 43 base region immediately upstream of open reading frame (ORF) 1a. Major differences were found in the region encoding the non-structural part of the ORF1a polyprotein, which shared only 47 % amino acid identity over 2503 residues of the six non-structural proteins (Nsps) encoded. Nsp2, thought to have a species-specific function, showed the greatest divergence, sharing only 32 % amino acid identity with LV and containing 120 additional amino acids in the central region. Nsps encoded by the 5h-proximal and central regions of ORF1b had from 66 to 75 % amino acid identity ; however, the carboxy-terminal protein CP4 was distinct (42 % identity). The ORF1a-1b frameshift region of 16244B had 98 % nucleotide identity with LV. Consistent with previous reports for North American isolates, the six structural proteins encoded were 58 to 79 % identical to LV proteins. The 3h NCR (150 nucleotides) was 76 % identical between isolates. These genomic differences confirm the presence of distinct North American and European PRRSV genotypes.

We studied the persistence of porcine reproductive and respiratory syndrome virus (PRRSV) in individual experimentally infected pigs, during a period of up to 150 days postinfection (dpi). The results of this study suggest that the persistence of PRRSV involves continuous viral replication but that it is not a true steady-state persistent infection. The virus eventually clears the body and seems to do it in most of the animals by 150 dpi or shortly thereafter. High genetic stability was seen for several regions of the persistent PRRSV's genome, although some consistent mutations in the genes of envelope glycoproteins and M protein were also observed.

Summary. Although live-attenuated vaccines have been used for some time to control clinical symptoms of the porcine reproductive and respiratory syndrome (PRRS), the molecular bases for the attenuated phenotype remain unclear. We had previously determined the genomic sequence of the pathogenic PRRSV 16244B. Limited comparisons of the structural protein coding sequence of an attenuated vaccine strain have shown 98% homology to the pathogenic 16244B. Here we have confirmed the attenuated phenotype and determined the genomic sequence of that attenuated PRRSV vaccine and compared it to its parental VR-2332 and the 16244B strains. The attenuated vaccine sequence was colinear with that of the strain 16244B sequence containing no gaps and 212 substitutions over 15,374 determined nucleotide sequence. We identified nine amino acid changes distributed in Nsp1␤, Nsp2, Nsp10, ORF2, ORF3, ORF5 and ORF6. These changes may provide the molecular bases for the observed attenuated phenotype.

Vesicular stomatitis (VS) viruses have been classified into two serotypes: New Jersey (VSNJV) and Indiana (VSIV). Here, we have characterized field isolates causing vesicular stomatitis in Brazil and Argentina over a 35-year span. Cluster analysis based on either serological relatedness, as inferred from virus neutralization and complement fixation assays, or nucleotide sequences of two separate genes (phosphoprotein or glycoprotein) grouped the field isolates into two distinct monophyletic groups within the Indiana serogroup. One group included seven viruses from Brazil and Argentina that were serologically classified as Indiana-2 and Cocal virus (COCV). The other group contained three viruses from Brazil that were serologically classified as Indiana-3 and the prototype of this group, Alagoas virus (VSAV). Interestingly, two vesiculoviruses that were isolated from insects but do not cause disease in animals, one from Brazil (Maraba virus; MARAV) and the other from Colombia (CoAr 171638), grouped into two separate genetic lineages within the Indiana serotype. Our data provide support for the classification of viruses causing clinical VS in livestock in Brazil and Argentina into two distinct groups: Indiana-2 (VSIV-2) and Indiana-3 (VSIV-3). We suggest using nomenclature for these viruses that includes the serotype, year and place of occurrence, and affected host. This nomenclature is consistent with that currently utilized to describe field isolates of VSNJV or VSIV in scientific literature.

This study examines apoptosis and viral neuropathogenesis in a murine model infected with vesicular stomatitis virus (VSV). VSV induces apoptotic cell death in cultured cell lines, raising the possibility that apoptosis of infected neurons and other target cells may contribute to disease and mortality. To determine whether or not VSV induces apoptosis in neural tissues, mice were inoculated intranasally with VSV. At 24, 48, 72, 96, and 120 hours postinfection, brain tissues were assayed for the presence of viral RNA by in situ hybridization and viral antigen by immunohistochemistry. Apoptosis was identified by in situ terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling and electron microscopy. Viral replication and lesions were observed predominantly in central nervous system neurons. Apoptotic cell death was restricted to the same regions of the brain in which infected cells and tissue injury were identified. Results suggest that VSV-induced apoptosis is a mechanism causing cell death, tissue injury, and mortality in VSV-infected mice.

In Brazil and Argentina, vesicular stomatitis (VS) is caused by distinct viral strains serologically related to the classical vesicular stomatitis virus Indiana (VSIV), namely VS Indiana-2 (VSIV-2) and VS Indiana-3 (VSIV-3). Here we describe the full-length genomic sequences and organization of the prototype strains of VSIV-2 Cocal virus (COCV) and VSIV-3 Alagoas virus (VSAV). These viruses showed similar genomic organizations to VSIV field isolates except that the non-structural C'/C proteins, markedly conserved throughout the vesiculoviruses, were absent in VSAV. Phylogenetic analyses consistently grouped COCV, VSAV and VSIV in a monophyletic group distinct from VSNJV, supporting the classification of these viruses within the Indiana serogroup.

Foot-and-Mouth Disease serotype O circulated endemically in Ecuador for many years, with an upsurge occurring in 2009. This manuscript describes retrospectively in vitro and in vivo laboratory studies to predict the field effectiveness of a commercial FMD vaccine to protect against the field strain, and explains the key actions and epidemiological strategies followed by the country to control the disease. The results established that the use of a good quality oil vaccine, manufactured with strains that were isolated long ago: O1 Campos Br/58 and A24 Cruzeiro Br/55; combined with the correct epidemiological strategies, are useful to control field strains when used in periodic biannual vaccination campaigns.

An indirect "sandwich" enzyme-linked immunosorbent assay (ELISA) using polyvalent and monovalent antisera was compared with the 50% complement fixation (CF50) test for the detection of foot-and-mouth disease (FMD) O, A, and C virus types. ELISA was more sensitive than CF50 tests when polyvalent antisera were used for detecting the 3 types of virus in epithelial samples, whereas ELISA using monovalent antisera was the least sensitive technique. The ELISA performed with polyvalent antisera was 9 times more sensitive for detecting FMD virus than that with monovalent antisera. However, viral isolation in cell culture was the most sensitive detection system. The combined use of ELISA with polyvalent antisera and cell culture inoculations was the most effective procedure for identifying FMD virus in epithelial samples from the field.