| BackgroundDengue virus(DENV)and Zika virus(ZIKV)are both positive,single-strand RNA viruses from the Flaviviridae family,spreading through mosquitos especially Aedes biting with the saliva injected into the blood or skin tissue of the host mainly human being around the world.The infections with DENV or ZIKV are becoming the most popular vector-borne disease due to the widely distributed mosquitos-Aedes(Aedes aegypti/Aedes albopictus).It may appear 3 to 7 days of in vivo incubation period after being infected by dengue virus.Some infectors show asymptom which leads the virus difficult to be under control and prevention from spreading,while others with the infection show typical clinical symptoms such as dengue fever,dengue hemorrhagic fever,Dengue severe syndrome.It caused a global attention and debate out of the outbreak of the Zika virus which causes neonatal microcephaly,Guillain-Barre syndrome,etc.in 2016.Some researches on epidemiology of DENV and ZIKV show that these two viruses travel the similar trend around the world and many of these epidemiological regions exist both viruses at the same time where the researchers caught mosquitos detected with DENV and ZIKV infected from the wild.Therefore,s tudying the phenomenon and mechanism of the interaction between DENV and ZIKV and host has very important theoretical value and application prospects for the prevention and treatment of dengue fever and Zika virus disease.MethodResearch on cases of dengue virus infection,attempting to know the changes of viral titer in the viremia from the dengue patients with or without symptoms.Following the cases,1268 totally,which are infected with DENV and hospitalized in the 8th people’s hospital in Guangzhou,since day 1 to discharge,we have recorded every single case’s viral titer,temperature of everyday in hospital to figure out the change of the viral titers to design the titers we used to make the artificial blood meal to test the Aedes infection rate when sipping different titers of virus in each blood meal which would give some new advice on the guidance of discharging dengue virus infections.Review on researches about the infection and epidemics of dengue virus and zika virus,gathering the average viral titer information of patients infected with the viruses to make the artificial blood meal which used to perform the experiment of the viruses infections on the Ae.albopictus in the lab.Oral fed with DENV and ZIKV,which are respectively resuscitated,gathered and mixed with fresh blood by the ratio 2:1 in different orders,Ae.albopictus,which were picked out with a full belly of blood from each feeding,were dissected for mid-guts and salivary glands at 7 days post infection(dpi)and 14 dpi to test the virus qualitatively and quantitatively to evaluate the competence and figure out whether the competence is influenced by the superinfection with DENV and ZIKV and the mechanism of the changes.ResultsWith the records of loads of dengue virus and temperature of each of the 1268 patients totally which hospitalized in the 8th people’s hospital of Guangzhou from June,2013 to December,2014,we found that,the viral loads of viremia from dengue virus infectors were reduced and temperatures were back to normal as time went by.The change of the average viral loads of all patients is ranged from 109 copies/ml to 103 copies/ml,according to which we designed our stimulation using the blood meal containing viral titers from 1010 copies/ml to 104 copies/ml,10 times as a gradient.Exposed to different gradients of viral titer,the Ae.aegypti and Ae.albopictus both show that as the viral titer in the blood meal decreased,the rate of infection reduced,what’ s more,when the titer dropped to 106 copies/ml,the infectious rate of Ae.albopictus at 14 dpi was down to 0 by PCRs.It is demonstrated that the viral titer in a blood meal lower than 106 copies/ml wouldn’t establish an infection in the mid-guts of Aedes.Dengue virus and zika virus can be epidemic at the same region so that it is very possible for Aedes,which are the important vectors for flaviviruses,to be superinfected with the two viruses in different orders and change the competence.We performed the infection experiment which used blood meals contain DENY or ZIKV to oral feed the Aedes in orders and then detected the virus qualitatively and quantitatively to evaluate the competence.It is changed when Aedes superinfected with DENV and ZIKV in either orders.ConclusionThe susceptibility of Aedes,as an effective vector of flaviviruses especially dengue virus,would be reduced as the viral titer in the blood meal dropped down when which is dropping down to a certain titer,the infection wouldn’t be established in Aedes.However,a flavivrius would be homologous interfered by other flavivirus which already established the infection in Aedes,and change the competence of vectors. |
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