Mayaro virus
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The Mayaro virus (MAYV) is a virus species belonging to the alphavirus genus . Within the genus it is due to close phylogenetic relationship together with the Chikungunya virus (CHIKV), O'nyong-nyong virus (ONNV), Ross River virus (RRV), Semliki forest virus (SFV) and others so-called SFV complex ( English Semliki Forest Virus Complex , also SFV group) assigned. The virus is transmitted in the tropical rainforest of South America by mosquitoes of the genus Haemagogus and probably also by the yellow fever mosquito Aedes aegypti in urban areas of the South American tropics . In humans it can cause Mayaro fever , an infectious disease similar to dengue fever , but milder and self-limiting. The disease and virus were named after the Mayaro region on the island of Trinidad , as the virus was first isolated from patient samples during an outbreak in Mayaro in 1954.
Genome and morphology
The MAYV virion has a diameter of about 70 nm and consists of the icosahedral capsid and the virus envelope . The symmetry of the capsid is transferred to the envelope through the interaction, which is common in alphaviruses, between the inner protein domains of the envelope proteins and the capsid protein, which thus has a regular arrangement of the envelope proteins.
The genome of the Mayaro virus consists of a single-stranded, 11,411 to 11,429 nt long RNA with positive polarity , which is packaged inside the capsid. At nt position 76 there is an additional UGA stop codon (“opal”). As with the other members of the Alphavirus genus , MAYV also has two open reading frames , each coding for a single polyprotein for the structural proteins or non-structural proteins. During translation, the polyproteins are cleaved into the individual virus proteins by viral and cellular proteases .
Within the group of the SFV complex, the MAYV is close to the Una virus on the basis of the genome sequences . This is considered to be the representative of the South American alphaviruses that are phylogenetically closest to the ancient alphaviruses.
Epidemiology and transmission
Various New World monkeys are considered to be the natural reservoir of the Mayaro virus . Mosquitoes act as a vector for transmission of these to humans. Similar to the yellow fever virus , a so-called sylvatic and urban cycle is assumed for transmission and the host-vector relationship. In the former, mosquitoes of the genus Haemagogus serve as vectors and New World monkeys as a reservoir, transmission to humans takes place here in rainforest areas. An urban cycle has been observed in individual outbreaks in urban areas where humans serve as the new reservoir host. The yellow fever mosquito, which was able to adapt to the Mayaro virus, is assumed to be the vector of this urban cycle. An experimental infection of the yellow fever mosquito with the Mayaro virus could be shown, but the susceptibility of the mosquitoes used to oral infection was only successful at very high virus concentrations. This indicates that the establishment of a permanent urban cycle is only possible to a limited extent, since the necessary virus concentration in the blood of sick people to infect the mosquitoes is not always reached and only for a short time.
The MAYV was isolated in two geographically differently distributed genotypes. The first genotype D to be isolated occurs in Trinidad, Brazil , Peru , Suriname , Bolivia and French Guiana , the rarer genotype L is restricted to the north of Brazil. Within the same genotype, the isolates differ only slightly, which indicates a special adaptation of the genotypes to specific, regional transmission routes and reservoirs.
Prophylaxis and therapy
Specific antiviral therapy against infections with the MAYV is not available. In addition to the interruption of the transmission by controlling the mosquito population and individual protective measures against mosquito bites as the currently only protective measures, there are experimental approaches for a live vaccine as a possible active vaccination.
literature
- RB Tesh et al .: Mayaro virus disease: an emerging mosquito-borne zoonosis in tropical South America. Clin. Infect. Dis. (1999) 28 (1), pp. 67-73 PMID 10028074
Individual evidence
- ↑ ICTV Master Species List 2018b.v2 . MSL # 34, March 2019
- ↑ a b c d ICTV: ICTV Master Species List 2019.v1 , New MSL including all taxa updates since the 2018b release, March 2020 (MSL # 35)
- ^ A. Lavergne et al .: Mayaro virus: complete nucleotide sequence and phylogenetic relationships with other alphaviruses . Virus Research (2006) 117 (2): pp. 283-290 PMID 16343676
- ↑ KC Long et al .: Experimental Transmission of Mayaro Virus by Aedes aegypti . The American Journal of Tropical Medicine and Hygiene (2011) 85 (4), pp. 750-757 PMID 21976583
- ↑ AM Powers, PV Aguilar et al .: Genetic relationships among Mayaro and Una viruses suggest distinct patterns of transmission. The American Journal of Tropical Medicine and Hygiene (2006) 75 (3), pp. 461-469 PMID 16968922
- ↑ WJ Weise et al .: A novel live-attenuated vaccine candidate for Mayaro Fever . PLoS negl. Trop. Dis. (2014) 7; 8 (8): e2969 PMID 25101995