Efficient intranasal immunization of newborn mice with recombinant adenovirus expressing rotavirus protein VP4 against oral rotavirus infection.

Efficacy of passive protection of newborn mice against rotavirus infection by the rotavirus VP4 protein expressed by an adenoviral vector in mice was studied. The VP4 gene was inserted into the E1 region of adenoviral vector pJM17. Recombinant adenovirus Ad5N/VP4 was grown in 293 cells. Intramuscular (i.m.), oral or intranasal (i.n.) immunization of newborn mice with Ad5/VP4 resulted in appearance of VP4-specific antibodies. Specific IgG antibodies were detected in the serum and intestine specimens of i.m. vaccinated mice. Oral immunization elicited serum IgG antibodies and intestinal IgG and IgA antibodies. Compared with i.m. and oral applications, i.n. immunization led to higher levels of serum IgG and intestinal IgG and IgA antibodies. Pups were challenged twice with simian rotavirus SA11 strain orally at the days 7 and 8 after birth. Pups born to i.n. immunized dams achieved 100% protection from rotavirus-induced diarrhea after both challenges. The protection of pups born to orally immunized dams was 80%, while only 30% of pups born to i.m. immunized dams were protected after both challenges. I.n. immunization was most efficient in inducing rotavirus VP4-specific serum, intestinal and milk IgG or IgA in mice that protected newborn mice completely.