Abstract
Brazilian Vaccinia virus had been isolated from sentinel mice, rodents and recently from humans, cows and calves during outbreaks on dairy farms in several rural areas in Brazil, leading to high economic and social impact. Some phylogenetic studies have demonstrated the existence of two different populations of Brazilian Vaccinia virus strains circulating in nature, but little is known about their biological characteristics. Therefore, our goal was to study the virulence pattern of seven Brazilian Vaccinia virus strains. Infected BALB/c mice were monitored for morbidity, mortality and viral replication in organs as trachea, lungs, heart, kidneys, liver, brain and spleen. Based on the virulence potential, the Brazilian Vaccinia virus strains were grouped into two groups. One group contained GP1V, VBH, SAV and BAV which caused disease and death in infected mice and the second one included ARAV, GP2V and PSTV which did not cause any clinical signals or death in infected BALB/c mice. The subdivision of Brazilian Vaccinia virus strains into two groups is in agreement with previous genetic studies. Those data reinforce the existence of different populations circulating in Brazil regarding the genetic and virulence characteristics.
Highlights
Vaccinia virus (VACV) is the prototype virus of the family Poxviridae and it was used as a live vaccine during the smallpox vaccination campaign
The induction of clinical signals such as ruffling fur and arching back was observed in all animals inoculated with VBH (Figure 1A), BAV, SpAn232 virus (SAV), Guarani P1 virus (GP1V) and the control VACVWR within days 2–3 p.i
The clinical signals of mice infected with BAV, SAV, GP1V, VBH and the control strain Western Reserve (WR) were associated with severe weight loss up to 25% on day five (WR), four (BAV and SAV) or three p.i. (VBH and GP1V) (Figure 2A)
Summary
Vaccinia virus (VACV) is the prototype virus of the family Poxviridae and it was used as a live vaccine during the smallpox vaccination campaign. The World Health Organization declared smallpox, the contagious and deadly disease caused by Variola virus, eradicated in 1980 [1]. The poxviruses still have a great impact in human and animal health due to the existence of emerging and reemerging zoonotic agents in this family. Cases of Cowpox virus human infections have been reported in Europe [2,3]. Monkeypox virus is endemic in the tropical rainforest villages of Central and Western Africa, causing sporadic cases in humans. 37 confirmed human cases have been recently reported in the United States [4,5].Outbreaks of Buffalopox virus affecting buffaloes, cows and humans have been reported in countries as India, Egypt and Bangladesh [6,7]
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