CD79A and infection: In addition to serum and salivary IgA antibodies, fecal IgA also are induced after infection.33,45,51 Although preexisting levels of norovirus-specific fecal IgA were not correlated with protection, in individuals who developed gastroenteritis, fecal IgA levels were inversely correlated with peak viral load in the stool,45 suggesting a role in the control of viral replication.