Intestinal immunity induced by inactivated poliovirus vaccine.

In order to detect any intestinal immunity against poliovirus infection induced by parenteral vaccination with inactivated poliovirus vaccine (IPV), experiments were conducted in monkeys (Macaca radiata). All animals were seronegative (antibody not detected at 1:2 dilution of serum) before investigation. Sixteen monkeys were vaccinated with three doses of IPV at monthly intervals. Groups of four vaccinated and two seronegative control animals were fed 100 median monkey infectious doses (100 MID50) of poliovirus type 1 (Mahoney strain) at 1, 4, 7 and 12 months after vaccination. While all control monkeys excreted poliovirus in the throat and faeces from day 2 to days 18-22, none of the vaccinated monkeys excreted virus. Thus, a high degree of intestinal immunity against infection was found. Although no evidence of infection was seen, antibody booster response occurred in most monkey fed virus 7 and 12 months after vaccination.