Caracterização biológica e filogenética de uma amostra de Vaccinia virus silvestre - SPAn232 (SAV)

Abstract

The SPAn232 virus (SPAnV) sample was isolated in the 1960s in the Cotia forest in the state of São Paulo during a government epidemiological surveillance program and was originally grouped as a Cotia virus (COTV - sample that circulated in the same regions where the SPAnV occurred) due to common serological cross-reactions among Poxviruses. However, a subsequent molecular study based on the sequences of the TK, VGF and ATI genes reclassified the sample as a variant of Vaccine virus, being renamed SPAn232 (SAV) (DA FONSECA et al., 2002). Other studies confirmed the phylogenetic relationship between the SAV variant and other Vaccinia virusBrazilian VACV-BR (DRUMOND, et al. 2008). However, a more recent study (AFONSO et al., 2012) using other samples collected by the Adolfo Lutz Institute suggested a possible VACV contamination of the COTV sample studied in the laboratories of the Federal University of Minas Gerais (UFMG). This work, therefore, in order to confirm if SPAn232 could be classified as a possible VACV strain, we performed a series of analyzes in a comprehensive biological and molecular study of the sample where we covered a complete evaluation of the virus multiplication cycle, phenotype of lysis plaques, formation of pustules or sores (pocks) in embryonic egg chorioallantoic membrane (MCA) and also the total sequencing of its genome. The pattern of the virus multiplication cycle and the lysis plate morphology presented a similarity to the data described in the literature for Vaccinia virus. With sequencing and phylogenetic analysis, the genome of the SAV sample was found to be closely related to the genome of the Vaccinia virus Western Reserve sample (Vaccine virus prototype VACV-WR and used herein as a reference) varying only in the length and percentage identity of 6 ORFs (open reading frame). Based on the results presented in this work it is assumed that the SPAn232 virus (SPAnv) isolate is another variant sample of Brazilian VACV that circulated and was isolated along with Cotia virus (COTV) in Brazilian forests in the 60's.