Mayaro virus (MAYV) is an enveloped, positive‑sense single‑stranded RNA virus that causes Mayaro fever, an acute febrile illness characterised by fever, rash and prolonged joint pain. It belongs to the genus Alphavirus within the family Togaviridae and is closely related to chikungunya virus. The spherical virion measures about 70 nanometres in diameter and contains a nucleocapsid surrounded by a lipid envelope bearing E1 and E2 glycoproteins.
Genome and Virology
The MAYV genome is roughly 11.5 kilobases long and contains two open reading frames separated by an internal junction region. The 5′ open reading frame encodes nonstructural proteins nsP1 to nsP4 that form the RNA replication complex, while the 3′ open reading frame encodes a structural polyprotein that includes the capsid, E3, E2, 6K/TF and E1 proteins. The nonstructural proteins are translated directly from the genomic RNA, whereas the structural proteins are produced from a subgenomic RNA. Following attachment to cell receptors and endocytosis, acidification of endosomes triggers E1-mediated membrane fusion and release of the nucleocapsid. Replication occurs on membrane-bound replication complexes at the plasma membrane, generating a negative-sense template and new genomic and subgenomic RNAs. Capsid proteins package genomic RNA, and virions assemble at the plasma membrane where E1/E2 glycoproteins insert; budding releases mature virus particles. Mayaro virus replicates in human monocytes, fibroblasts and endothelial cells and in the midgut and salivary glands of mosquito vectors.
Epidemiology and Clinical Features
Mayaro virus was first isolated in Trinidad in 1954 and is endemic to the Amazon basin and other regions of tropical South America. It is maintained in a sylvatic cycle involving canopy-dwelling Haemagogus mosquitoes and nonhuman primates, rodents and birds. Human infections typically occur in rural or forested areas when people are bitten by infected mosquitoes, especially during activities such as logging or farming. Occasional outbreaks have been reported in Brazil, Bolivia, Peru and Venezuela, with sporadic cases among travellers returning to non-endemic countries. Clinical presentation resembles chikungunya, with sudden onset of fever, headache, myalgia, rash and severe arthralgia that can persist for weeks or months. Mortality is rare, but the prolonged joint pain can be debilitating. There is no specific antiviral treatment or licensed vaccine. Vector control and personal protective measures remain the primary means of prevention, and there is concern that adaptation to urban Aedes mosquitoes could facilitate wider spread.
Mayaro virus highlights the potential for sylvatic alphaviruses to emerge and cause outbreaks in humans, underscoring the need for surveillance and vector control in tropical regions.
Related Terms: Chikungunya virus, Ross River virus, O’nyong-nyong virus, Dengue virus, Alphavirus