Mayaro virus disease is a
mosquito
Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small flies within the family Culicidae (from the Latin ''culex'' meaning " gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish for "li ...
-borne
zoonotic
A zoonosis (; plural zoonoses) or zoonotic disease is an infectious disease of humans caused by a pathogen (an infectious agent, such as a bacterium, virus, parasite or prion) that has jumped from a non-human (usually a vertebrate) to a human. ...
pathogen
In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...
endemic
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
to certain humid
forests
A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...
of
tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
. Infection with Mayaro virus causes an acute, self-limited
dengue
Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Symptoms typically begin three to fourteen days after infection. These may include a high fever, headache, vomiting, muscle and joint pains, and a characteristic ...
-like illness of 3–5 days' duration.
The causative virus, abbreviated MAYV, is in the family ''
Togaviridae This category is for articles about virus families (or redirects to such articles). There should be no subcategories.
families
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity ( ...
'', and
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''
Alphavirus
''Alphavirus'' is a genus of RNA viruses, the sole genus in the ''Togaviridae'' family. Alphaviruses belong to group IV of the Baltimore classification of viruses, with a positive-sense, single-stranded RNA genome. There are 32 alphaviruses, ...
''. It is closely related to other
alphavirus
''Alphavirus'' is a genus of RNA viruses, the sole genus in the ''Togaviridae'' family. Alphaviruses belong to group IV of the Baltimore classification of viruses, with a positive-sense, single-stranded RNA genome. There are 32 alphaviruses, ...
es that produce a dengue-like illness accompanied by long-lasting
arthralgia
Arthralgia (from Greek ''arthro-'', joint + ''-algos'', pain) literally means ''joint pain''. Specifically, arthralgia is a symptom of injury, infection, illness (in particular arthritis), or an allergic reaction to medication.
According to MeSH, ...
. It is only known to circulate in tropical
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
.
Virology
Mayaro virus has a structure similar to other alphaviruses. It is an enveloped virus and has an icosahedral capsid with a diameter of 70 nm. The virus genome is composed of a linear, positive-sense, single-stranded RNA with 11,429 nucleotides, excluding the 5’ cap nucleotide and 3’ poly(A) tail.
The MAYV RNA genome contains the 5' untranslated region, 3' noncoding region, and two open reading frames (ORFs). The 5' proximal and 3' proximal ORFs are separated by a short, noncoding sequence and represent two-thirds and one-third of the genomic RNA, respectively. The 5’-proximal ORF codes for a polyprotein that after cleavage forms nonstructural proteins (nsP1, nsP2, nsP3, nsP4) and the 3’-proximal ORF with a 26S promoter codes for a polyprotein that is cleaved into structural proteins to generate capsid proteins and envelope surface glycoproteins (E1, E2, E3, C, 6K).
The nonstructural proteins (nsP) play different functions in the virus cycle. The nsP1 is an mRNA-capping enzyme, nsP2 has protease activity, and nsP4 is a RNA-direct RNA polymerase. The structural polyprotein is cleaved into six chains: capsid protein (C), p62, E3 protein or spike glycoprotein E3, E2 envelope glycoprotein or spike glycoprotein E2, 6K protein, and E1 envelope glycoprotein known also as spike glycoprotein E1.
[Netto M.C.M.G., Shirako Y., Strauss E.G., Carvalho M.G.C., Strauss J.H. Submitted (FEB-2000) to the EMBL/GenBank/DDBJ databases] The envelope lipid component is critical for virus particle stability and infectivity in mammalian cells
Once the virus enters into the host cell, the genomic RNA is released into the cytoplasm, where the two ORFs are translated into proteins and the synthesis of negative-stranded RNA starts. A consecutive synthesis of positive-stranded RNA takes place.
The MAYV sequences analysis showed two genotypes (D and L). The amplicon used for phylogenetic analysis includes E1 and E2 glycoprotein genes and the 3' NCR. The genotype D is distributed in Trinidad, Brazil, French Guiana, Surinam, Peru, and Bolivia, while the genotype L is limited to the north-central region of Brazil.
Diagnosis
The MAYV infection is characterized by fever, headache, myalgia, rash, prominent pain in the large joints, and association with rheumatic disease,
but these signs and symptoms are unspecific to distinguish from other ''arboviruses''. The MAYV infection can be confirmed by laboratory testing such as virus isolation, RT-PCR, and serology. The virus isolation in cell culture is effective during viremia. RT-PCR helps to identify virus. Serology tests detect antibodies like IgM and the most common assay is IgM-capture enzyme-linked immunosorbant assays (ELISA). This test usually requires a consecutive retest to confirm increasing titers.
While the IgG detection is applied for epidemiology studies.
Epidemiology
The virus's transmission cycle in the wild is similar to the continuous