As NS2 and M2 mRNA are generated specifically through mRNA splicing following viral replication and absent within the IAV virion itself, detection of the 3ʹ spliced junction of NS2 and M2 specifically indicates a productive infection, and the subsequent segregation of IAV mRNA into ApoBDs, rather than RNA carryover from fully assembled virions. The gene discussed is LZTR1; the disease is infection.