Immune responses and protection obtained with rotavirus VP6 DNA vaccines given by intramuscular injection

Intramuscular (i.m.) injection of murine VP6 DNA vaccines raised high titer s of rotavirus-specific serum IgG and IEA antibodies in BALB/c mice. A Th1- like antibody response was generated based on the ratio of serum IgG2a to I gG1 antibodies. Rotavirus-specific serum IgA but not fecal IEA was detected in mice prior to rotavirus challenge. Partial protection against rotavirus challenge was achieved as measured by reduction of rotavirus antigen shedd ing in feces. A similar level of protection was found with a bovine rotavir us VP6 DNA vaccine against a murine rotavirus challenge, suggesting that he terologous protection can be obtained by immunizing with VP6 DNA vaccines. We did not directly test for cytotoxic T lymphocyte (CTL) activity, but in vivo depletion of CD8(+) T cells in mice immunized with a murine VP6 DNA va ccine did not significantly change the duration of virus shedding or the pa ttern of protection obtained. This finding suggested that CD8(+) CTL activi ty was not essential for the partial protection we obtained by i.m. immuniz ation of mice with VP6 DNA vaccines. (C) 2001 Elsevier Science Ltd. All rig hts reserved.