Expected and Unexpected Features of the Newly Discovered Bat Influenza A-like Viruses

Ma, Wenjun; García-Sastre, Adolfo; Schwemmle, Martin

All efforts to isolate an infectious virus from bat species have failed to date, although HL17NL10 or HL18NL11 RT-PCR-positive tissue and rectal swab samples were used in these studies [2, 3] . The challenge in isolating infectious influenza A-like viruses could also be related to the atypical surface proteins of these viruses, especially since there is no evidence that the cell lines used for virus isolation, including bat, human, canine, and avian cells [2, 3, 8, 9] , express the receptors that allow viral particle uptake. It might be then not surprising that the generation of wild-type influenza A-like HL17NL10 or HL18NL11 viruses using reverse genetic approaches has not succeeded. However, from these rescue attempts, we learned by electron microscopy studies that viral particles are released from human HEK293T cells (Fig 2) [8] . Thus, subsequent binding and internalization of the viral particles in different cells that are normally used for the amplification of recombinant IAV might be impaired.