Haemophilus influenzae serotype a (Hia)

Haemophilus influenzae serotype a (Hia) is a Gram-negative, capsulated bacterium that has emerged as a significant cause of invasive disease, particularly in the post-Haemophilus influenzae type b (Hib) vaccine era (Ulanova & Tsang, 2014, Lancet Infect Dis). The primary virulence factor and therapeutic target for Hia is its capsular polysaccharide, which consists of a repeating unit of glucose and ribitol phosphate (Cox et al., 2017, Vaccine). This capsule allows the bacterium to evade the host immune system by preventing opsonophagocytosis, facilitating systemic spread (Potts et al., 2019, J Clin Microbiol). Hia is responsible for severe clinical manifestations, including meningitis, pneumonia, and septicemia, with a high burden observed in indigenous populations in North America and Australia (CDC, 2022). Current therapeutic strategies involve the use of broad-spectrum antibiotics such as ceftriaxone, while preventative efforts are focused on the development of Hia-specific conjugate vaccines that target the capsular antigen to elicit a protective immune response (Shuel et al., 2021, Expert Rev Vaccines).

Other names

H. influenzae type aHiaHaemophilus influenzae type a

Antimicrobial agents target bacterial cell wall synthesis, protein synthesis, or DNA replication, while conjugate vaccines induce the production of opsonizing antibodies directed against the Hia capsular polysaccharide to facilitate bacterial clearance by the immune system (Cox et al., 2017, Vaccine; Shuel et al., 2021, Expert Rev Vaccines).