Araçatuba virus: a vaccinialike virus associated with infection in humans and cattle

Abstract

We describe a vaccinialike virus, Araçatuba virus, associated with a cowpoxlike outbreak in a dairy herd and a related case of human infection. Diagnosis was based on virus growth characteristics, electron microscopy, and molecular biology techniques. Molecular characterization of the virus was done by using polymerase chain reaction amplification, cloning, and DNA sequencing of conserved orthopoxvirus genes such as the vaccinia growth factor (VGF), thymidine kinase (TK), and hemagglutinin. We used VGF-homologous and TK gene nucleotide sequences to construct a phylogenetic tree for comparison with other poxviruses. Gene sequences showed 99% homology with vaccinia virus genes and were clustered together with the isolated virus in the phylogenetic tree. Araçatuba virus is very similar to Cantagalo virus, showing the same signature deletion in the gene. Araçatuba virus could be a novel vaccinialike virus or could represent the spread of Cantagalo virus.

Figure 1

Lesions from suspected Araçatuba virus on hand of dairy farm worker (milker) (A) and teats of cow (B).

Figure 2

(A) Nucleotide sequence of the Araçatuba virus hemagglutinin (HA) and comparison with same sequences from Cantagalo virus and vaccinia virus–Western Reserve (WR). Box indicates deletion region conserved in the sequences of both Araçatuba and Cantagalo viruses, but not in vaccinia virus, Western Reserve (WR). Star (*) indicates regions conserved in all three viruses. (B) Phylogenetic tree constructed based on the nucleotide sequence of poxvirus thymidine kinase genes. Nucleotide sequences were obtained from GenBank (accession nos. X01978, M35027, M57768, AF163843, AF163844, EVY18384, U94848, K02025, S51129, L22579, S55844, X52655, and M14493). (C) Phylogenetic tree constructed based on the nucleotide sequence of poxvirus vaccinia growth factor genes. Nucleotide sequences were obtained from GenBank (accession nos. U18340, L22579, U18337, U18338, X69198, M35027, J02421, S61049, CVU76380, AF170722, and M15921). The Treecon program (29) was used to construct trees. Bootstrap confidence intervals are shown on branches (100 sample iterations).

Figure 3

Detection and restriction fragment length polymorphism taxonomic analysis of the Araçatuba virus ATI gene. Primers based on the ATI gene nucleotide sequence from the cowpox virus were used to amplify the gene. (A) The amplified fragments were resolved on 0.6% agarose gel with ethidium bromide. Line 1 shows Araçatuba virus; line 2 shows vaccinia virus; and line 3 shows cowpox virus, Brighton strain. (B) Products obtained after amplification were digested with XbaI restriction enzyme. Fragments were resolved on 1.5% agarose gel stained with ethidium bromide. Arrowheads indicate molecular sizes (line 1, Araçatuba virus; line 2, vaccinia virus; line 3, cowpox virus, Brighton strain.