Paenibacillus larvae antigens (P. larvae antigens)

Paenibacillus larvae antigens are the molecular components derived from the Gram-positive, spore-forming bacterium Paenibacillus larvae, the causative agent of American Foulbrood (AFB) in honeybees (Apis mellifera) (Ebeling et al., 2016). These antigens include structural proteins, such as S-layer proteins, and virulence factors like the toxins Plx1, Plx2, and C3larvin, which facilitate the invasion and liquefaction of honeybee larvae (Genersch, 2010). In the veterinary pharmaceutical industry, these antigens are utilized as the primary component of bacterin-based vaccines designed to provide prophylactic protection to honeybee colonies. The use of these antigens as a vaccine target was pioneered by Dalan Animal Health and received conditional approval from the USDA in 2023. The therapeutic application of these antigens involves a unique mechanism known as transgenerational immune priming (TGIP). When a queen bee consumes the killed P. larvae antigens, the fragments are transported via the hemolymph to the ovaries and incorporated into the eggs through the protein vitellogenin (Dickel et al., 2022). This exposure primes the immune system of the developing larvae, significantly reducing mortality rates when the colony is exposed to the pathogen (USDA-APHIS, 2023). This approach represents a major shift in apiary management, offering a sustainable alternative to the traditional use of antibiotics and the destruction of infected hives.

Other names

American Foulbrood antigensAFB antigensPaenibacillus larvae bacterinP. larvae whole-cell lysateHoneybee vaccine antigens

Induction of transgenerational immune priming (TGIP) where antigens are ingested by the queen bee, transported via the hemolymph to the ovaries, and incorporated into developing eggs through the protein vitellogenin, thereby stimulating the larval immune system to recognize and combat P. larvae infection (Dickel et al., 2022; USDA-APHIS, 2023).