Intestinal Resistance in the Experimental Enteric Infection of Mice with a Mouse Adenovirus

Abstract

The influence of cyclophosphamide (Cy) on the establishment and duration of the intestinal resistance against enteric infection with a mouse adenovirus, strain K87, was examined in inbred mice, strain DK1. When Cy (40 mg/kg/day) was administered to mice for 17 days from the time of virus challenge, a clear prolongation of viral growth and a delayed appearance of neutralizing (NT) antibody in the intestinal wall as well as in the serum were observed. When Cy (40 mg/kg/day, for 14 days) was administered after cessation of viral growth (4 to 6 weeks after virus challenge) and part of the mice were rechallenged with the virus, titers of NT antibody and immunoglobulins became significantly lower than those in control mice not treated with Cy, and regrowth of the virus was observed in eight out of twenty-five Cy-treated mice, regardless of the presence or absence of rechallenge. In this experiment, antibody titers in the intestinal contents of eight virus-positive mice were significantly lower than those of the remaining seventeen virus-negative mice. The time when the decrease of intestinal NT antibody was maximum coincided with the time of the maximal frequency of viral regrowth. It was discussed that these facts might present an evidence to support the idea that the intestinal resistance was acquired through local NT antibody belonging to-IgA in the intestinal tract.

Fluctuation of Antiviral Resistance in the Intestinal Tracts of Nude Mice Infected with a Mouse Adenovirus

“…This result is basically the same as that obtained from conventional DK1 mice (2,6) and germfree ICR mice (2, 4) reported previously.…”

“…It has been reported by Hashimoto et al (2,4,11) that oral administration of mouse adenovirus strain K87 to conventional DK1 and germfree ICR mice results in viral proliferation in the intestinal tract at weeks 1 and 2 followed by the appear anceof antiviral resistance in the intestinal tract from around week 3. Challenging BALB/c nu/+ mice with adenovirus yielded very similar infection characteristics in this current experiment.…”

“…Perhaps it is more apt at this point to hypothesize the subliminal existence of virus in the intestinal tract which reproliferates on termination of the transitory resistance exhibited by the host. As for the resistance shown by nu/+ mice, it is believed that the resistance which is correlated with the rise in NT-Ab titer is due to the same mechanism whereby conventional DK1 mice (2,8) and germfree ICR mice (2, 4) acquired resistance, i.e. by IgA antibody localized in sec tionsof the intestinal tract.…”