Rapid inactivation of rotaviruses by exposure to acid buffer or acidic gastric juice

Inactivation rates of three bovine and several primate-origin rotaviruses were determined during exposure to acid buffers at pH 2.0, pH 3.0 or pH 4.0. Each rotavirus was inactivated at pH 2.0 (the acidity most resembling the normal fasting stomach) very rapidly, with half-lives for infectivity determined to be 1 min or less. Each rotavirus was inactivated at a much slower rate at pH 3.0; inactivation at pH 4.0 was minimal. No remarkable differences in acid resistance between different rotavirus strains were detected. Although these determinations were performed at room temperature (23 degrees C), experiments at diverse temperatures indicated an even more rapid rate of viral inactivation by acid at normal body temperature (37 degrees C). Studies of rotavirus exposed to natural human gastric juice at pH 1.8 or pH 2.1 revealed a rate of virus inactivation similar to that observed with glycine buffer of identical pH.