Abstract
Dengue is a mosquito-borne disease that has been an epidemic in China for many years. Aedes albopictus is the dominant Aedes mosquito species and the main vector of dengue in China. Epidemiologically, dengue mainly occurs in Guangdong Province; it does not occur or rarely occurs in other areas of mainland China. This distribution may be associated with climate, mosquito density, and other factors in different regions; however, the effect of temperature on the vector competence of Ae. albopictus for dengue viruses (DENV) remains unclear. In this study, Ae. albopictus was orally infected with dengue virus 2 (DENV-2) and reared at constant temperatures (18, 23, 28, and 32°C) and a fluctuating temperature (28–23–18°C). The infection status of the midguts, ovaries, and salivary glands of each mosquito was detected by polymerase chain reaction (PCR) at 0, 5, 10, and 15 days post-infection (dpi). DENV-2 RNA copies from positive tissues were quantified by quantitative real time PCR (qRT-PCR). At 18°C, DENV-2 proliferated slowly in the midgut of Ae. albopictus, and the virus could not spread to the salivary glands. At 23 and 28°C, DENV-2 was detected in the ovaries and salivary glands at 10 dpi. The rates of infection, dissemination, population transmission, and DENV-2 copies at 28°C were higher than those at 23°C at any time point. At 32°C, the extrinsic incubation period (EIP) for DENV-2 in Ae. albopictus was only 5 dpi, and the vector competence was the highest among all the temperatures. Compared with 28°C, at 28–23–18°C, the positive rate and the amount of DENV-2 in the salivary glands were significantly lower. Therefore, temperature is an important factor affecting the vector competence of Ae. albopictus for DENV-2. Within the suitable temperature range, the replication of DENV-2 in Ae. albopictus accelerated, and the EIP was shorter with a higher temperature. Our results provide a guide for vector control and an experimental basis for differences in the spatial distribution of dengue cases.
Highlights
Dengue virus (DENV) is a mosquito-borne flavivirus that can cause a series of diseases, including dengue fever (DF), dengue hemorrhagic fever (DHF), and dengue shock syndrome (DSS) (Guzman and Harris, 2015)
Constant Temperatures In this study, a total of 602 Ae. albopictus females reared at 18, 23, 28, and 32◦C were used to measure the rates of infection, dissemination, and transmission of dengue viruses (DENV)-2
Our results showed that dengue virus 2 (DENV-2) was confined to the midguts of Ae. albopictus at 18◦C and could invade the salivary glands between 23 and 32◦C
Summary
Dengue virus (DENV) is a mosquito-borne flavivirus that can cause a series of diseases, including dengue fever (DF), dengue hemorrhagic fever (DHF), and dengue shock syndrome (DSS) (Guzman and Harris, 2015). Spatial distribution showed that the highest number of cases was found in Guangzhou City, the capital of Guangzhou Province; few cases were present in Shenzhen City; and no cases were seen in Meizhou City (Xiao et al, 2016). These differences in distribution were probably due to climatic fluctuation, population density, mosquito density, and other factors (Jing et al, 2017)
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