Emerging alphaviruses in the Americas: Chikungunya and Mayaro

Chikungunya virus (CHIKV) and Mayaro virus (MAYV) are emergent arthropod-borne viruses that produce outbreaks of acute febrile illness with arthropathy. Despite their different continental origins, CHIKV and MAYV are closely related and are components of the Semliki Forest Complex of the Alphavirus (Togaviridae). MAYV and, more recently, CHIKV, which are both transmitted by Aedes mosquitoes, have resulted in severe public health problems in the Americas, including Brazil. In this review, we present aspects of the pathogenesis, clinical presentation and treatment of febrile illnesses produced by CHIKV and MAYV. We also discuss the epidemiological aspects and effects related to the prophylaxis of infections by both viruses.

Zoonotic encephalitides caused by arboviruses: transmission and epidemiology of alphaviruses and flaviviruses

In this review, we mainly focus on zoonotic encephalitides caused by arthropod-borne viruses (arboviruses) of the families Flaviviridae (genus Flavivirus) and Togaviridae (genus Alphavirus) that are important in both humans and domestic animals. Specifically, we will focus on alphaviruses (Eastern equine encephalitis virus, Western equine encephalitis virus, Venezuelan equine encephalitis virus) and flaviviruses (Japanese encephalitis virus and West Nile virus). Most of these viruses were originally found in tropical regions such as Africa and South America or in some regions in Asia. However, they have dispersed widely and currently cause diseases around the world. Global warming, increasing urbanization and population size in tropical regions, faster transportation and rapid spread of arthropod vectors contribute in continuous spreading of arboviruses into new geographic areas causing reemerging or resurging diseases. Most of the reemerging arboviruses also have emerged as zoonotic disease agents and created major public health issues and disease epidemics.

Alphaviruses isolated from culex mosquitoes, 2001

In September – December 2001 period, from 4987 female Culex mosquitoes collected in Cat Que commune, Hoai Duc district, Ha Tay province, 4 viral species were isolated by clone C6/36 cells of Vero and Aedes albopictus. Among them, 2 species were alpha virus, 01VN61 virus was isolated from Culex tritaeniorhynchus and 01VN62 virus from Culex gelidus, both strains were adapted to 1-2 days age mice. By sequencing technique on E1 gene and 3 NCR gene area, 01VN62 virus was identified as Safiyama virus, a virus of alpha virus

Analysis of alphavirus polypeptides by two dimensional polyacrylamide gel electrophoresis.

Semliki Forest, Sindbis and Chikungunya viruses were grown and radiolabeled with [3H]-amino acids in Vero cells. Analysis of virus infected cell lysates by two dimensional polyacrylamide gel electrophoresis resulted in detection of polypeptides of molecular, weights corresponding to those of E1, P62, ns60, ns70/72 for Semliki Forest virus, the C, E1, 6K, 14Κ, ΡΕ2, P97, ns60, ns82 for Sindbis virus and E1. P62, P97, ns70/72 for Chikungunya virus. Charge and molecular weight heterogeneity in the precursor polypeptide P62 of Semliki Forest virus was detected. Structural polypeptides e.g. E1 and E2 of Semliki Forest virus and C, E1, E2 of Sindbis virus and E1 of Chikungunya virus were detected when purified radiolabeled virus preparations were analyzed by two dimensional polyacrylamide gel-electrophoresis. Membrane glycoprotein Ε1 and E2 of Semliki Forest and Ε1 of Sindbis and Chikungunya viruses exhibited charge heterogeneity. In contrast to the marked difference in isoelectric points of E1 and E2 of Sindbis virus; E1 and E2 of Semliki Forest virus had almost identical isoelectric points.