Belo Horizonte virus: a vaccinia-like virus lacking the A-type inclusion body gene isolated from infected mice.

Here is described the isolation of a naturally occurring A-type inclusion body (ATI)-negative vaccinia-like virus, Belo Horizonte virus (VBH), obtained from a mousepox-like outbreak in Brazil. The isolated virus was identified and characterized as an orthopoxvirus by conventional methods. Molecular characterization of the virus was done by DNA cross-hybridization using Vaccinia virus (VACV) DNA. In addition, conserved orthopoxvirus genes such as vaccinia growth factor, thymidine kinase and haemagglutinin were amplified by PCR and sequenced. All sequences presented high similarity to VACV genes. Based on the sequences, phenograms were constructed for comparison with other poxviruses; VBH clustered consistently with VACV strains. Attempts to amplify the ATI gene (ati) by PCR, currently used to identify orthopoxviruses, were unsuccessful. Results presented here suggest that most of the ati gene is deleted in the VBH genome.