Inactivation of poliovirus I (Brunhilde) single particles by chlorine in water.

Like the Mahoney strain, the Brunhilde strain of poliovirus aggregated slowly in dilute phosphate-carbonate buffer at pH 6 but not at all at or above pH 7. Infectivity decreased at rates approximately proportional to the concentration of free chlorine present at pH 6 over the entire range of 5 to 40 micrometer. The addition of 0.1 M NaCl to the buffer increased the rate about twofold, but this strain was still twice as resistant as the Mahoney strain. At pH 10, inactivation was much slower than at pH 6, but when 0.1 M NaCl was added, the rate was increased 31-fold, making the OCl- at pH 10 over three times more effective than HOCl at pH 6.