Chikungunya Virus Transmission at Low Temperature by Aedes albopictus Mosquitoes

Abstract

Aedes albopictus is an important vector of chikungunya virus (CHIKV). In Australia, Ae. albopictus is currently only known to be present on the islands of the Torres Strait but, should it invade the mainland, it is projected to spread to temperate regions. The ability of Australian Ae. albopictus to transmit CHIKV at the lower temperatures typical of temperate areas has not been assessed. Ae. albopictus mosquitoes were orally challenged with a CHIKV strain from either Asian or East/Central/South African (ECSA) genotypes (107 pfu/mL), and maintained at a constant temperature of either 18 °C or 28 °C. At 3- and 7-days post-infection (dpi), CHIKV RNA copies were quantified in mosquito bodies, and wings and legs using real time polymerase chain reaction (qRT-PCR), while the detection of virus in saliva (a proxy for transmission) was performed by amplification in cell culture followed by observation of cytopathic effect in Vero cells. Of the ≥95% of Ae. albopictus that survived to 7 dpi, all mosquitoes became infected and showed body dissemination of CHIKV at both temperatures and time points. Both the Asian and ECSA CHIKV genotypes were potentially transmissible by Australian Ae. albopictus at 28 °C within 3 days of oral challenge. In contrast, at 18 °C none of the mosquitoes showed evidence of ability to transmit either genotype of CHIKV at 3 dpi. Further, at 18 °C only Ae. albopictus infected with the ECSA genotype showed evidence of virus in saliva at 7 dpi. Overall, infection with the ECSA CHIKV genotype produced higher virus loads in mosquitoes compared to infection with the Asian CHIKV genotype. Our results suggest that lower ambient temperatures may impede transmission of some CHIKV strains by Ae. albopictus at early time points post infection.

Chikungunya outbreak in Bangladesh (2017): Clinical and hematological findings

“…A higher percentage of cases was observed in adult females (56.7%) than males (38%) and female children (43.3%). However, previously published reports have indicated that both sexes suffer equal burdens of the disease [36,37]. The higher percentage of adult female cases may be due to higher levels of exposure to infected vectors in the home environment since Bengali women spend more time at home, and the mosquitoes are commonly found indoors [38][39][40][41].…”

Temperature alters gene expression in mosquitoes during arbovirus infection

“…aegypti mosquitoes were orally infected with a CHIKV strain from the Asian genotype (GenBank accession MF773560) and held at 18, 28 or 32 °C for either 3- or 7-days post infection (dpi) (n=18-20 mosquitoes per combination of T °C and dpi). Using qRT-PCR (as per [26]), we found that at 3 dpi, the number of virus genome copies in mosquito bodies (including heads but without wings and legs) held at 32 °C was significantly higher than that from mosquitoes held at the other temperatures ( Fig. 1 A ).…”

“…Five to 7-day old Ae. aegypti were orally challenged with virus-infected or sheep blood alone (control), using methods previously described [26]. A CHIKV strain from the Asian Genotype (GenBank ID: MF773560) was prepared as described in [26] and delivered in oral feeds at a final pfu of 1 × 10 7 per ml of virus stock.…”

“…mosquitoes to transmit viruses, with higher temperatures following infection leading to increased viral replication and earlier transmission potential [10, 11]. Conversely, lower ambient temperatures lead to decreased viral replication and delayed transmission by mosquitoes [12, 13]. Exactly how ambient temperature influences the physiological, molecular and genetic interactions between virus and mosquito during infection remains poorly elucidated.…”

The Role of Temperature in Shaping Mosquito-Borne Viruses Transmission

“…First described as temperature dependent by Davis in 1932 ( Davis, 1932 ), EIP is often used as an index of vector competence. Higher temperatures are associated with reduced EIP and enhanced vector competence in many virus-vector pairings ( Chamberlain and Sudia, 1955 ; Richards et al, 2007 ; Xiao et al, 2014 ; Liu et al, 2017 ; Wimalasiri-Yapa et al, 2019 ; Winokur et al, 2020 ). Virus replication rates generally increase with temperature, and since dissemination and transmission correlate with viral load ( Kramer and Ciota, 2015 ), lower temperature is generally less advantageous for arbovirus transmission.…”