Xenosurveillance proof-of-principle: Detection of and SARS-CoV-2 antibodies in mosquito blood meals by (pan)-specific ELISAs.

Blood-fed insects can be used to analyse the host blood for circulating vertebrate pathogens or antibodies directed against them. We tested whether naturally acquired antibodies in different host species can be detected by host-specific and pan-specific ELISAs in mosquito blood meals. Cat- and alpaca-specific ELISAs could detect antibodies against or SARS-CoV-2 in blood meals of for 48 and at least 24 h, respectively. In the pan-specific ELISA, a conjugated protein A/G and anti-IgY were used to detect antibodies of mammalian and bird hosts. Thus, antibodies could be detected in mosquitoes fed on blood from humans, chicken, pig, and sheep up to 72 h after the blood meal. The results, however, demonstrated differences in sensitivities between different host species, and the assay requires further evaluation. Xenosurveillance with antibody detection in mosquito blood meals can be an additional surveillance tool that would especially be helpful when it is difficult to sample the potential animal reservoirs.