ARS | Publication request: Characterization of secreted proteases of Paenibacillus larvae, potential virulence factors in honeybee larval infection

Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 17, 2009
Publication Date: November 25, 2009
Citation: Antunez, K., Anido, M., Schlapp, G., Evans, J.D., Zunino, P. 2009. Characterization of secreted proteases of Paenibacillus larvae, potential virulence factors in honeybee larval infection. Journal of Invertebrate Pathology. 102(2):129-132.

Interpretive Summary: While honey bees and the crops they pollinate are affected by numerous pathogens, American foulbrood disease (AFB) is the only honey bee disease that is regulated throughout the U.S. This disease is highly contagious and can lead to the destruction of entire apiaries. The bacterial agent that causes AFB is widespread and there is much interest in determining how and why this bacterium switches into a more virulent lifestyle. Here we describe several proteins that are likely to be involved in the damages to bee health caused by the AFB bacterium. This information can be used by researchers working to develop antibiotic control methods toward AFB and to breed bees that resist AFB disease.

Technical Abstract: Paenibacillus larvae is the causative agent of American Foulbrood (AFB), the most severe bacterial disease that affects honeybee larvae. AFB causes a significant decrease in the honeybee population affecting the beekeeping industry and agricultural production. After infection of larvae, P. larvae secretes proteases that could be involved in pathogenicity. In the present article, we present the secretion of different proteases by P. larvae during the replication of vegetative cells. Inhibition assays confirmed the presence of metalloproteases. Two different proteases patterns (PP1 and PP2) were identified in a collection of P. larvae isolates from different geographic origin. Forty nine percent of P. larvae isolates showed pattern PP1 while 51 % exhibited pattern PP2. Most isolates belonging to genotype ERIC I – BOX A presented PP2, most isolates belonging to ERIC I – BOX C presented PP1 although relations were not significant. Isolates belonging to genotypes ERIC II and ERIC III presented PP2. No correlation was observed between the secreted proteases patterns and geographic distribution, since both patterns are widely distributed in Uruguay. According to exposure bioassays, isolates showing PP2 are more virulent than those showing PP1, suggesting than differences in pathogenicity are related to the secretion of proteases.