Glória Galembeck (World Mosquito Project / Fiocruz Minas)
Aedes aegypti mosquitoes that carry Wolbachia bacteria have the reduced ability to transmit Mayaro arbovirus. The finding is in an article published in the latest issue of the online scientific journal Scientific Reports, which integrates the Nature group and covers all areas of natural sciences. The study was conducted by a group of researchers from the René Rachou Institute (Fiocruz Minas), located in the city of Belo Horizonte, and resulted in the article Wolbachia significantly impacting the vector competence of Aedes aegypti for Mayaro virus.
The research was done from a circulating virus isolated in Brazil, multiplied in Aedes aegypti cells. The virus was mixed with human blood and used to feed two groups of Aedes aegypti: field mosquitoes and mosquitoes having Wolbachia bacteria in their bodies. The analysis, carried out after mosquito infection, showed that Aedes aegypti with Wolbachia had much less virus in the head region (where the salivary glands are found), while field mosquitoes (which do not carry Wolbachia) were found significantly more infected with Mayaro virus.
In another study, the saliva of mosquitoes (with and without Wolbachia) exposed to Mayaro virus was extracted and then injected into field Aedes aegypti, which had not yet had contact with the virus. The result indicated that when receiving the saliva of mosquitoes with Wolbachia, the mosquitoes were not infected, while most of the ones that receive the saliva coming from control mosquitoes became infected. This laboratory test shows the reduced ability to transmit the virus of mosquitoes with Wolbachia.
"The study shows that potentially the method of releasing Aedes aegypti with Wolbachia into the environment to reduce disease transmission capacity is effective for one more arbovirus, in addition to dengue, zika and chikungunya," said Luciano Moreira, a researcher at Fiocruz and one of the authors of the article. Moreira is the leader of the World Mosquito Program (WMP) in Brazil, an international initiative to fight mosquito diseases that is conducted in Brazil by Fiocruz. WMP is present in 11 other countries in South America, Asia, the Pacific Ocean and Oceania.
In addition to Moreira, Thiago Nunes Pereira, Marcele Neves Rocha, Pedro Henrique Ferreira Sucupira and Fabiano Duarte Carvalho, all IRR/Fiocruz researchers signed the article, which is available here.
Mayaro virus (MAYV) is an arbovirus of the family Togaviridae, genus Alphavirus, as well as chikungunya virus (CHIKV), which is genetically and antigenically related. Mayaro fever, caused by the virus, is a wild zoonosis transmitted mainly by the mosquito Haemagogus janthinomys. Aedes aegypti, which is an urban mosquito, has the ability to act as vector of Mayaro virus, which has already been demonstrated experimentally. However, there is no known case that has been transmitted this way.
"We have not yet identified Aedes aegypti in the city of Manaus with Mayaro virus. Our researchers identify that Mayaro is circulating, but not how transmission occurs," explained Sérgio Luiz Bessa Luz, a researcher and director of Leônidas and Maria Deane Institute (Fiocruz Amazonas), located in Manaus. Cases of Mayaro fever have already been reported in the states of Pará, Tocantins and Goiás, according to the Ministry of Health.