In the present study, IgA antibody response was found positive in 7 (63.6%) HIV seropositive Cryptosporidium positive (Gp I) and 5 (50%) HIV seronegative Cryptosporidium positive (Gp III) including 1(25%) post-transplant (Gp IIIa) patient while 4 (20%) HIV seropositive Cryptosporidium negative, 2 (10%) HIV seronegative Cryptosporidium negative healthy and 2 (8%) patients with other parasitic diseases were found positive for IgA response. The gene discussed is CD79A; the disease is parasitic infectious disease.