EFFECT OF ACID PH, SALTS, AND TEMPERATURE ON INFECTIVITY AND PHYSICAL INTEGRITY OF ENTEROVIRUSES

At 2.degree. and 30.degree. C, enteroviruses [poliovirus, coxsackievirus and echovirus] are more stable on the acid than on the alkaline side of neutrality. In the range from pH 3-9, temperature is so influential that the fastest inactivation rate at 2.degree. C is slower than the slowest inactivation rate at 30.degree. C. Specific ions or salts also affect the rate of inactivation of enteroviruses. NaCl and other chloride salts enhance the inactivation of poliovirus at pH 3. NaCl is considerably less effective against poliovirus in the range of pH 4.5-7.0 than at pH < 4.5. Loss of RNA infectivity of the virus particle [in primary rhesus monkey kidney cells] proceeds as rapidly as the loss of infectivity of the particle itself, except at pH 3 in the presence of MgCl2. Inactivation results in alterations to the physical integrity of enteroviruses. At pH 5 and 7 RNA hydrolysis of poliovirus particles occurs; and at pH 3, 5, 6 and 7 the nucleic acid becomes susceptible to RNase. Only virus particles inactivated at pH 3 show a sensitivity to chymotrypsin. The hemagglutinins of echovirus type 7 are destroyed during inactivation at pH 3, 4, 5 and 6; at pH 6 this alteration precedes the loss of infectivity. The pH of the suspension is a primary determinant of the mechanism of virus destruction and possibly of the loss of infectivity at these temperatures.