Antigenic Complementarity between Influenza A Virus and Haemophilus influenzae may Drive Lethal Co-Infection Such as that Seen in 1918-19 Pandemic

Antigenic Complementarity between Influenza A Virus and Haemophilus influenzae may Drive Lethal Co-Infection Such as that Seen in 1918-19 Pandemic

Pfeiffer’s bacillus, now known as Haemophilus influenzae (HI), was strongly implicated in the high lethality of the 1918-19 influenza pandemic. Influenza virus (IV) infection is often complicated by (HI) super-infection and certainly was so in 1918-19. We propose that the influenza pandemic of 1918-19 was caused by concurrent pandemics of IV and HI that overwhelmed co-infected individuals through antigenic synergy between the two infections. Using T cell receptor sequences specific for IV and HI antigens, we demonstrate that IV and HI antigens induce molecularly complementary TCR responses.