Zika virus is thought to be primarily transmitted by Aedes aegypti mosquitoes. The authors were interested in the extent to which A. albopictus mosquitoes in the United States are capable of transmitting the virus and whether this is influenced by the virus dose or virus strain. They examined multiple doses of representative Zika virus strains in A. aegypti and A. albopictus mosquitoes. The authors found that virus preparation (fresh vs. frozen) significantly affects virus infectivity in mosquitoes. The 50% infectious doses are 6.1–7.5 log10 PFU/mL, with a minimum infective dose of 4.2 log10 PFU/mL. A. albopictus mosquitoes were more susceptible to infection than A. aegypti mosquitoes but the transmission efficiency for A. aegypti mosquitoes was higher, suggesting that there may be a transmission barrier in A. albopictus mosquitoes. Therefore Zika virus transmission is relatively inefficient overall and is dependent upon virus strain and mosquito species, however there is the potential for A. albopictus mosquitoes to become major vectors in the Americas.
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