Molecular analysis of the N gene of canine distemper virus in dogs in Brazil

Eleven central-nervous-system samples collected from stray dogs between 2000 and 2004 were found positive by RT-PCR, which amplified a 480bp fragment of the N gene of canine distemper virus (CDV). Phylogenetic analysis based on partial N-gene sequences showed four major clusters. All dog strains segregated into cluster I, with a mean nucleotide identity of 95.8 percent and 95.6 percent with the Onderstepoort and Lederle vaccine strains, respectively. Cluster II contained all the raccoon-related strains, cluster III Orient strains and Cluster IV the Onderstepoort and Lederle vaccine strains, with a mean nucleotide identity of 99.7 percent between them. This is the first report of phylogenetic analysis of CDV strains in Brazil.

Onze amostras de sistema nervoso central de cães coletados entre 2000 e 2004 foram positivas pela RT-PCR, a qual amplificou um fragmento de 480pb do gene N do vírus da cinomose canina (VCC). A análise filogenética baseada na seqüência parcial do gene N mostrou quatro principais agrupamentos genéticos. Todas as amostras de cães segregaram no agrupamento I, com identidade média de nucleotídeos de 95,8 por cento e 95,6 por cento com as amostras vacinais Onderstepoort e Lederle, respectivamente. O agrupamento II agregou todas as amostras relacionadas aos guaxinins. O agrupamento III agregou amostras orientais e o agrupamento IV agregou as amostras vacinais Onderstepoort e Lederle, com identidade média de nucleotídeos de 99,7 por cento entre elas. Este é o primeiro relato de análise filogenética de amostras de VCC no Brasil.

Effect of actinomycin D on simian rotavirus (SA11) replication in cell culture

Rotaviruses are the major cause of viral diarrhea in humans and animals. Actinomycin D (Act D) is an antibiotic that intercalates DNA and therefore inhibits DNA-dependent transcription. The current study was carried out to assess the influence of Act D on the replication of simian rotavirus (SA11) in cell culture. Virus-infected MA-104 cell cultures were studied in the presence of Act D at concentrations of 1.25 and 2.5 æg/ml. Treatment of rotavirus-infected cells with 2.5 æg/ml Act D 48 h post-infection reduced the cytoplasmic metachromasia after staining with acridine orange by 25 percent. Viral RNA labeled with ³H-uridine in the presence of the drug was separated by polyacrylamide gel electrophoresis. Viral RNA replication was not affected by Act D, but increased ³H-uridine uptake was demonstrable by infected cells in the presence of the drug. This possibly was due to the inhibition of cellular RNA synthesis by Act D, which thus enhances incorporation of the radionuclide into the viral RNA. Act D reduced the number of infected cells presenting virus-specific fluorescence 48 h post-infection by more than 50 percent. These data suggest that Act D may have complexed with viral RNA and prevented newly synthesized mRNA from being translated, but may not have prevented early replication