Oral inoculation of mice with low doses of microencapsulated, noninfectious rotavirus induces virus-specific antibodies in gut-associated lymphoid tissue.

The capacity of an aqueous-based system of microencapsulation to enhance virus-specific humoral immune responses was evaluated in mice orally inoculated with noninfectious rotavirus (simian rotavirus strain RRV). Mice were orally inoculated with 1.75 or 0.35 microgram of inactivated RRV (iRRV) or microencapsulated iRRV. Sera, intestinal contents, and organ cultures of gut-associated lymphoid tissues (GALT) were tested for the presence of rotavirus-specific antibodies. Virus-specific IgA was produced by small intestine lamina propria lymphocytes in animals inoculated with 1.75 or 0.35 microgram of microencapsulated virus, but not in mice inoculated with unencapsulated virus. Virus-specific IgA in sera and intestinal contents were not predictive of intestinal organ culture responses. Microencapsulation may be an efficient way of inducing virus-specific immune responses in GALT after oral inoculation with small quantities of viral antigen. In addition, delayed release of virus from microcapsules may obviate the need for booster immunizations.