Differential alpha-gal expression during and tick feeding and development: A driver for the development of alpha-gal syndrome in South Africa.
The presence of galactose-α-1,3-galactose (alpha-gal) in tick salivary antigens has been implicated to initiate host IgE responses resulting in sensitization to alpha-gal. We sought to investigate the presence of alpha-gal in different anatomic locations in native South African tick species at different feeding and developmental stages and the ability of sera from our allergic cohort to bind to these tick proteins. Alpha-gal-containing proteins in laboratory-reared ticks at different feeding and developmental stages were detected through Western blotting and immunohistochemical staining. IgE and IgG4 toward the tick proteins were analyzed via ELISA. There is differential expression of alpha-gal in endemic South African ticks and . Immunoblotting demonstrated an increase in the prominence of alpha-gal-containing protein bands in salivary glands to be proportional to feeding time. Alpha-gal in both fed and unfed ticks was localized in the salivary acini and testes. IgE and IgG4 to antigens were significantly raised in alpha-gal-allergic individuals. There was a correlation between anti- IgE and anti-alpha-gal IgE in the alpha-gal-allergic group. Inhibition of human serum anti-alpha-gal IgE to and proteins was significantly reduced by the addition of bovine thyroglobulin. We anticipate repeated exposure to differentially expressed and alpha-gal-containing salivary proteins during feeding to cause alpha-gal sensitization.