Assessment of Hepatitis B and C Virus nucleic acids in the mosquito, Culex pipiens L. and its possible role of transmission.

Abstract

Infections with hepatitis B (HBV) and hepatitis C (HCV) viruses are public health burden in several countries. Transmission through blood is the most likely potential method of HBV and HCV infections. This study was designed to examine the possibility that the mosquito Culex pipiens (Diptera: Culicidae) could serve as a vector of HBV and HCV transmission. A series of laboratory experiments were conducted using female Cx. pipiens that fed on HBV and HCV infected blood meals using chick feeding membrane technique. Symbiotic (normal gut bacteria) and aposymbiotic (sanitized gut bacteria) adult female mosquitoes were tested for loading HBV and HCV nucleic acids during different periods post infection. Viral titers were measured using RT-PCR. The effects of mosquito viral infection on some mosquito biological parameters were measured showing significant decline. The possibility of HBV and HCV transmission through mosquitoes was studied. Our results proved HBV DNA loading in head region, it could be present till 5 hrs for symbiotic and 7 hrs for aposymbiotic females. HBV DNA was detected till the fourth day and fifth day after experimental infection of symbiotic and aposymbiotic females with load (1068.5 and 753.4 IU/ml/ female). While, in measuring a positive viral loading of HCV in the head region for 60 and 90 min when estimated in symbiotic and aseptic group respectively by q polymerase chain reaction technique. In gut region infected mosquitoes could harbour HCV RNA till 5 days in symbiotic & 6 days in aposymbiotic group with viral load (200 and 300 IU/ml/ female) respectively. No detection of any viral load in examining the salivary glands of female mosquitoes after infection with HBV and HCV. An ex vivo assay results demonstrated that HBV and HCV infected mosquitoes were able to transmit the virus to human blood samples mechanically. No biological role was detected during all experiments. Results indicated that mosquito gut symbionts have a distinct role in persistence of HBV and HCV in infected mosquitoes. The present data concluded that the mosquito Cx. pipiens could play as a mechanical vector for transmission of HBV and HCV. After isolation of gut bacteria, BioMérieux API 20E and VITEK® 2 systems were used for bacterial identification, where the isolated bacteria were identified as Acnietobacter trifolii, Acnietobacter baumanii, Esccherichia coli, Klebsiella ornitholytica, Enterobacter cholacae, Staphlyococcus aureus, and Microbacterium olevarians.