Mosquito-transmitted viruses - the great Brazilian challenge

ABSTRACT Arboviruses pose a serious threat to public health worldwide, overloading the healthcare system and causing economic losses. These viruses form a very diverse group, and in Brazil, arboviruses belonging to the families Flaviviridae and Togaviridae are predominant. Unfortunately, the number of arboviruses increases in proportion with factors such as deforestation, poor sanitation, climate changes, and introduction of new viruses like Chikungunya virus and Zika virus. In Brazil, dengue is endemic, along with the presence of other arboviruses. The situation is complicated by the scarcity of diagnostic infrastructure and the absence of approved vaccines for these diseases. Disease control, thus, relies solely on vector control. Therefore, enhanced clinical knowledge and improved general awareness about these arboviruses are indispensable to tackle diagnostic inadequacies.

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.

Inhibition of Mayaro virus replication by prostaglandin A1 and B2 in Vero cells

The effect of prostaglandins (PGA1 and PGB2) on the replication of Mayaro virus was studied in Vero cells. PGA1 and PGB2 antiviral activity was found to be dose-dependent. However, while 10 µg/ml PGB2 inhibited virus yield by 60 percent, at the same dose PGA1 suppressed virus replication by more than 90 percent. SDS-PAGE analysis of [35S]-methionine-labelled proteins showed that PGA1 did not alter cellular protein synthesis. In infected cells, PGA1 slightly inhibited the synthesis of protein C, while drastically inhibiting the synthesis of glycoproteins E1 and E2

Serum concentration and increased temperature alter Mayaro virus RNA and protein synthesis in Aedes albopictus (mosquito)-infected cells

We have previously shown the inhibition of Mayaro virus multiplication in Aedes albopictus-infected cells maintained at a supraoptimal temperature for growth (37§C) and a stimulation of virus production in response to high serum concentrations in the incubation medium. In the present study, we addressed the question of how the effect of continuous heat stress and high serum concentration soon after infection interfere with virus macromolecule synthesis. Cells maintained at 28§C in the presence of 2 percent serum synthesized a viral genomic RNA of 12 kb and a subgenomic RNA of 5.2 kb 6 h post-infection. Analysis of the protein profile showed the presence of the viral nucleocapsid protein of 34 kDa (P34). However, if infected cells were maintained at 37§C, a smear starting immediately below the 5.2-kb RNA was noticed and the viral P34 was not detected by SDS-PAGE. Addition of 10 percent serum to the growth medium of infected cells maintained at 37§C results in a viral RNA profile and proteins synthesis similar to those observed in cultures kept at 28§C, i.e., the smear was not observed and the P34 protein was detected. The results suggest that the inhibition of virus multiplication by temperature may be related to the inhibition of viral nonstructural protein synthesis early during infection. The presence of high serum levels in the incubation medium protects macromolecule synthesis against heat stress

Prostaglandin A1, inhibits replication of Mayaro virus in Aedes albopictus cells

Prostaglandin A1 (PGA1) reduced Mayaro virus replication in Aedes albopictus (mosquito) cells in culture. The highest nontoxic dose of PGA1, 7.5µM, decreased virus production by 90 percent. In Mayaro virus-=infected cells, PGA1 inhibited virus-specific protein synthesis. However, in mock-infected cells the presence of PGA, stimulated the synthesis of several proteins with molecular masses of 70, 57 and 23 kDa, respectively. The data obtained from this study show that PGA1 plays a role in the metabolic regulation of Aedes albopictus cells, blocking the synthesis of Mayaro virus and inducing the synthesis of cellular polypeptides

Effect of high temperature on Aedes albopictus cells infected with Mayaro virus

the multiplication of Mayaro virus in Aedes albopictus cells was drastically inhibited after incubation at 37-C. The effect of short-term exposure of infected cells to high temperatures (heat shock) produced a preferential translation of the heat shock messengers when compared to the viral mRNAs. When cells were shifted back to 28-C (the optimum growth temperature for Aedes albopictus cells), preferential translation of viral mRNA occurred. Although the infected cells were programmed for preferential translation of viral messengers, the therminal treatment was able to shif the translational machinery towards synthesis of heat shock proteins