Data from: MHC class II DRB diversity predicts antigen recognition and is associated with disease severity in California sea lions naturally infected with Leptospira interrogans

We examined the associations between California sea lion MHC class II DRB
(Zaca-DRB) configuration and diversity, and leptospirosis. As Zaca-DRB
gene sequences are involved with antigen presentation of bacteria and
other extracellular pathogens, we predicted that they would play a role in
determining responses to these pathogenic spirochaetes. Specifically, we
investigated whether Zaca-DRB diversity (number of genes) and
configuration (presence of specific genes) explained differences in
disease severity, and whether higher levels of Zaca-DRB diversity
predicted the number of specific Leptospira interrogans serovars that a
sea lion's serum would react against. We found that serum from
diseased sea lions with more Zaca-DRB loci reacted against a wider array
of serovars. Specific Zaca-DRB loci were linked to reactions with
particular serovars. Interestingly, sea lions with clinical manifestation
of leptospirosis that had higher numbers of Zaca-DRB loci were less likely
to recover from disease than those with lower diversity, and those that
harboured Zaca-DRB.C or –G were 4.5 to 5.3 times more likely to die from
leptospirosis, regardless of the infective serovars. We propose that for
leptospirosis, a disadvantage of having a wider range of antigen
presentation might be increased disease severity due to immunopathology.
Ours is the first study to examine the importance of Zaca-DRB diversity
for antigen detection and disease severity following natural exposure to
infective leptospires.