Studies on the Immune Capabilities of Chiroptera

Abstract

K values based on 90% neutralization of φX174 indicate that the response of bats held at 24°C and 37°C to immunization with multiple doses of 10¹⁰ plaque-forming units (PFU) was less and that production of ME-sensitive antibodies was more pronounced than in rabbits or guinea pigs. Neutralization of φX174 by early bat antibodies was especially dependent upon the presence of a heat-labile serum factor or factors. Once a response was elicited in bats (24°C), antibody production continued at a relatively high level for a long period of time. An anamnestic response was demonstrated at the latter time interval in which the quantity of predominantly ME-resistant antibodies, having minimal requirements for heat-labile factors, approached that induced earlier in guinea pigs. A rapid response with early conversion to ME-resistant antibodies was evoked in bats (24°C) after single doses of 10¹¹ PFU of φX174 (without adjuvant) or 10⁹ PFU of φX174 in complete adjuvant. Considerable dissociation of φX174 from bat antibodies occurred when less than 90% of the phage had been neutralized, but was not remarkable when inactivation was greater than 90%. The proportionate loss of anti-φX174 activity in relation to concentration of antibodies diminished upon dilution of bat plasma pools as the immune response progressed, suggesting that an increase in affinity of antibodies for φX174 had occurred, possibly in association with changes in the major type of antibody being produced. Potential effects of the nature and degree of antigenic stimulation upon immune responses in bats are discussed.