We examined the potentially conflicting effects that microfilarial ( MF) enhancement of viral infectivity and MF-induced mortality in mosquitoes have on the vectorial capacity of Aedes aegypti (L.), Aedes triseriatus (Say), and Aedes taeniorhynchus (Wiedemann) for Venezuelan equine encephalitis virus (VEE) when mosquitoes feed on gerbils co-infected with Brugia malayi (Buckley). Groups of mosquitoes were fed on gerbils that were either dually infected (VEE plus B. malayi MF) or singly infected (VEE only). Mosquito mortality was recorded daily, and 5-8 d later, surviving mosquitoes were assayed for disseminated viral infection. The contrasting effects of MF enhancement and MF-induced mortality differed among mosquito species and were determined by the nature and consequences of MF penetration through the mosquito midgut, but not to differences in mosquito susceptibilities to parenterally introduced virus. In Ae. aegypti, MF-induced mortality was high and tended to eliminate any significant effect of MF enhancement. In Ae. triseriatus, MF-induced mortality was low, and feeding on dually infected hosts resulted in 9 times as many mosquitoes with disseminated viral infections as did feeding on singly-infected hosts. In Ae. taeniorhynchus, MF-induced mortality was extremely high, yet under our experimental conditions, feeding on a dually infected hosts resulted in nearly 30 times as many disseminated infections as did feeding on singly infected hosts. The final outcome on vectorial capacity depended on the specific combination of MF, virus, and mosquito species involved. Therefore, future efforts toward understanding MF enhancement should be directed toward mosquito-virus-parasite species combinations that occur together in nature.

A new microfilaria from the Indian palm squirrel

Brugia malayi microfilariae (Nematoda: Filaridae) enhance the infectivity of Venezuelan equine encephalitis virus to Aedes mosquitoes (Diptera: Culicidae).

Brugia -type microfilariae were noted in a Madras tree shrew, Anathana ellioti (Waterhouse) from Andhra Pradesh, India. This is a new host record, the first report from the genus Anathana and the second report from the tree shrews.

Brugia-type microfilariae in the Madras tree shrew Anathana ellioti (Waterhouse).

Hydrogen sulfide, a small molecule, produced by endogenous enzymes, such as CTH, CBS, and MPST using L-cysteine as substrates, has been reported to have numerous protective effects. However, the key problem that the target of H2S and how it can affect the structure and activity of biological molecules is still unknown. Till now, there are two main theories of its working mechanism. One is that H2S can modify the free thiol in cysteine to produce the persulfide state of the thiol and the sulfhydration of cysteine can significantly change the structure and activity of target proteins. The other theory is that H2S, as an antioxidant molecule, can directly break the disulfide bond in target proteins, and the persulfide state of thiol can be an intermediate product during the reaction. Both phenomena exit for no doubt since they are both supported by large amounts of experiments. Here, we will summarize both theories and try to discuss which one is the more effective or direct mechanism for H2S and what is the relationship between them. Therefore, we will discover more protein targets of H2S with the mechanism and understand more about the effect of this small molecule.

A new microfilaria from the Indian palm squirrel

Citations

Brugia malayi microfilariae (Nematoda: Filaridae) enhance the infectivity of Venezuelan equine encephalitis virus to Aedes mosquitoes (Diptera: Culicidae).

Brugia-type microfilariae in the Madras tree shrew Anathana ellioti (Waterhouse).

A Common Molecular Switch for H 2 S to Regulate Multiple Protein Targets

References

Yellow Fever in Central Uganda, 1964. Part II. Report of a Fatal Case.

Blood parasites in the himalayan flying squirrel