Susceptibility Of Aedes Mosquitoes To Zika Virus And Mechanism Of The Interaction

Background:Zika virus(ZIKV)is a mosquito-borne virus that can cause ZIKV disease.Severe ZIKV infection can lead to adult Guillain-Barre syndrome;infection during pregnancy causes microcephaly in infants.The global ZIKV pandemic in 2016 led to"public health emergencies of international concern".The main vectors of ZIKV are Aedes aegypti and Aedes albopictus.At present,there are no effective treatment drugs or vaccines for ZIKV.The prevention and control of mosquitoes is the most effective method to prevent and control the spread and epidemic of the disease.Investigating the susceptibility and mechanism of Aedes albopictus and Aedes aegypti to ZIKV has important theoretical value and guiding significance for the control of vector mosquitoes and associated infectious diseases.Objective:Study the susceptibility of Aedes albopictus and Aedes aegypti to the ZIKV strains PRVABC59 and FSS13025 and explore the interaction mechanism between mosquitoes and viruses.Methods:Plaque test was performed to detect virus titers;indirect immunofluorescence was used to detect the fluorescence expression in tissues infected by ZIKV;PRVABC59(PR)and FSS13025(FS)strains were used to infect Aedes albopictus(laboratory strains,field strains)and Aedes aegypti.The midgut,head,ovary,and salivary glands of the mosquitoes were dissected at 4,7,10,and 14 days post infection(dpi).RT-PCR and qRT-PCR were used to detect virus infection and virus copy numbers.RNA was extracted from each tissue of virus-infected mosquitoes and subjected to RNA sequencing.Candidate genes that were differentially expressed in ZIKV-infected of Aedes albopictus were knocked down using RNAi.Genetically modified Aedes albopictus were infected with the PR strain of ZIKV.Mosquito tissues were dissected 4 and 10 dpi to detect the virus infection rate and virus copy number.Results:In ZIKV-infected vector mosquitoes green fluorescence of the ZIKV NS1 protein antibody was observed in the midgut,ovary and salivary glands.The virus was detected in the ovary at 4 dpi after PR strain infection in Aedes albopictus,while the FS strain required 7 days.The infection rate,dissemination rate,transmission rate,ovary infection rate and viral RNA copies in PR strain-infected Aedes albopictus and Aedes aegypti were higher than those in FS strain-infected mosquitoes.Aedes albopictus infected with the PR strain had higher viral RNA copies in the midgut than Aedes aegypti.The dissemination rate,transmission rate and ovary infection rate of Aedes aegypti were higher than those of Aedes albopictus at 10 dpi.Aedes albopictus had lower viral RNA copies in the ovarian and salivary glands than Aedes aegypti.After infection with the PR strain and FS strain,21-nt viral small RNAs were produced.The PR strain produced 26054 vsiRNAs after Aedes albopictus infection and 8818 vsiRNAs were produced by the FS strain.Compared with those of the PR strain,502 of the 545 immune-related genes were upregulated after infection with the FS strain.According to the transcriptome data,three differentially expressed genes were selected.Knocking down the AALF020660 gene(cytochrome p450 enzyme gene,cyp450)reduced the susceptibility of mosquitoes to ZIKV,while knocking down the AALF006708 gene(PIWI protein-related gene)increased the susceptibility of mosquitoes to ZIKV,but knocking down the AALF009469 gene(cyp450)had a weaker effect on the ability of mosquitoes to resist the virus.Conclusion:The susceptibility of mosquitoes to the ZIKV PR strain is higher than that to the FS strain;Aedes aegypti is more susceptible to ZIKV than Aedes albopictus.Cytochrome p450 and PIWI in mosquitoes can interact with the virus to change the susceptibility of mosquitoes to ZIKV.