The Venezuelan Equine Encephalomyelitis Complex of Group a Arthropod-Borne Viruses, Including Mucambo and Pixuna from the Amazon Region of Brazil

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  • The Belém Virus Laboratory, The Rockefeller Foundation Virus Laboratories, Belém, Pará, Brazil
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Mucambo virus (BeAn 8), previously described as a strain of Venesuelan equine encephalomyelitis (VEE) virus from the Amazon region of Brazil, can be differentiated from VEE virus by hemagglutination - inhibition, complement - fixation and neutralization testing. Pixuna virus, a hitherto undescribed agent isolated in the same region of Brazil in 1961, is related to both VEE and Mucambo, and the three viruses form an antigenic complex in arbovirus group A. VEE and Mucambo are more closely related to each other by all three tests than either is to Pixuna.

A horse inoculated with Mucambo virus developed fever, leukopenia and viremia. Inoculation of Pixuna virus in another horse failed to produce fever or circulating virus, and the horse did not develop viremia after challenge with Mucambo.