MeiZhi Irene Li; Pei Sze Jeslyn Wong; Lee Ching Ng; Cheong Huat Tan

“ A significant increase (*) (P<0.001) in mean viral titer was observed between days 7 and 10 pe. Discussion Recent unprecedented spread of chikungunya virus (CHIKV) in many parts of the world, with millions of people affected, exemplifies how arboviruses can adapt and affect human health on a global scale [31] . Singapore's vulnerability to emerging and re-emerging arboviruses is accentuated by the country's location as a popular tourist and business hub, high dependency on migrant workers, tropical climate, dense population, and the presence of potential mosquito vectors. ”

“ The present study describes the oral susceptibility of a Singapore field strain Ae. aegypti to ZIKV, under condition that simulate local climate.
Materials and Methods Mosquitoes Ae. aegypti, used for the experimental infection, were derived from eggs collected in the Western part of Singapore during a weekly ovitrap surveillance study to determine mosquito population density. Ovitraps were placed in public areas, mostly along the common corridors of public housing. The surveillance study was conducted by colleagues from the Environmental Health Institute. ”

“ Considering the geographic spread and the possible impact on susceptible human populations, mosquito-borne diseases are currently considered as a major threat to global health in both developing and developed world [28] , [29] . According to Gushulak et al. [30] , the threat of emerging infectious diseases is mainly influenced by the migration and mobility of the human populations. ”

“ Studies have showed that loss of glycosylation motif due to mutation has been found to affect the replication rates of tick-borne encephalitis virus. DENV, and WNV in both vector hosts and insect cell lines and the dissemination rate of WNV in different Culex spp. mosquitoes [53] , [54] , [55] , [56] . Despite the absence of this aa 154 glycan, the present study has shown that ZIKV MR766 has a high dissemination rate in Singapore's Ae. aegypti. ”

“ The midguts and salivary glands from each mosquito were individually transferred to 2 mL microtubes containing 250 μL of M199. These organs were then homogenized using five mm stainless steel grinding balls (Retsch, Germany) in a MM301 mixer mill (Retsch, Germany) set at frequency of 12/sec for 1 min. The supernatant of the homogenate was applied in the viral titer assay. All dissecting needles were dipped in 80% ethanol and cleaned before being re-used. All experiments were conducted inside an ACL-2 facility. ”

“ The strain used in our current study, MR766, is the Ugandan prototype strain and the only strain available to our laboratory. It would be very interesting to study and compare the recent epidemic ZIKV 2007 EC strain in Ae. aegypti, especially in the light of a four amino acid motif found in the viral envelope genes of the ZIKV 2007 EC strain that are absent in the MR766 strain [17] . Unfortunately, no ZIKV 2007 EC was isolated during the outbreak in Yap Island. ”

“ Dodson, BL & Kramer, LD (2011) , Requirement of glycosylation of West Nile virus envelope protein for infection of, but not spread within, Culex quinquefasciatus mosquito vectors, vol. 85, pp. 374–378, 21813861 MoudyRMPayneAFDodsonBLKramerLD, pmid:21813861 ↑ Bryant, JE; Calvert, AE; Mesesan, K; Crabtree, MB & Volpe, KE (2007) , Glycosylation of the dengue 2 virus E protein at N67 is critical for virus growth in vitro but not for growth in intrathoracically inoculated Aedes aegypti mosquitoes, vol. ”