Vectorial capacity of Culex gelidus (Theobald) mosquitoes to certain viruses of public health importance in India.

BACKGROUND & OBJECTIVES: Culex gelidus, a widely prevalent mosquito in India and Southeast Asia region, is an important vector of Japanese encephalitis virus (JEV). Experimental studies have shown its potential to transmit West Nile, Kunjin, Murray Valley encephalitis and Ross River viruses. An attempt was therefore made to study its susceptibility and vector competence to some of the arboviruses of public health importance in India. METHODS: Mosquitoes were infected with six viruses, viz. JEV, chikungunya (CHIKV), Chandipura (CHPV), Chittoor (CHITV), Ingwavuma (INGV) and Umbre (UMBV) by intra thoracic inoculation to determine virus susceptibility and vector competence. Growth kinetics of the viruses were studied by determining the titres of inoculated mosquitoes on different days post-infection by titration in Vero E6 cells. Vector competence was studied by detecting the presence of the viruses in saliva of infected mosquitoes. RESULTS: All the six viruses were replicated in Cx. gelidus. JEV, CHPV, CHIKV and CHITV yielded > 5 log10TCID50/ml virus while UMBV and INGV yielded approx 4log10TCID50/ml virus. JEV, CHIKV and CHITV could be detected in the saliva of the infected mosquitoes, while CHPV, INGV and UMBV could not be detected in the saliva of the infected mosquitoes. INTERPRETATION & CONCLUSION: Replication potential and vector competence of Cx. gelidus to some of the viruses of public health importance in India, viz. JEV, CHIKV, CHITV etc, pose a serious threat to general population, especially in the wake of spurt in its population in certain parts of India.