Abstract
Experiments were carried out on the plaque formation method of enteroviruses and in vitro marker tests of poliovirus. Comparison of the plaque technique and plaque-forming capacity was made between poliovirus type 1 and echovirus type 6 by using the Hela, FL, and monkey kidney (MK) cell culture systems. Intratypic specificity of antiserum was studied by the Wecker test. The temperature of the T-marker test and changes of T-marker were examined by passage of poliovirus type 1 strains on HeLa cells at 35°C.
1) The second agar overlay method was better than the single agar overlay method in the case of the plaque formation technique on continuous cell lines.
2) Plaque-forming capacity and infectivity titer of echovirus type 6 were greater on FL cells thann on MK cells.
3) The Wecker test used in the present studies was a slight modification of the original test (1960). RIST was calculated 4 days after inoculation. Isolates of poliovirus type 1 were differentiated in to sero-intratypic groups by it.
4) The T-marker test was carried out by a modification of the method reported by Yoshioka et al. (1959) and Carp et al. (1962). The test on HeLa cells was incubated in a water bath at 35 or 39°C (that on MK cells was incubated at 35 or 40°C & ±0.02°C) after 4 days of inoculation. Then plaques were counted. The results of the tests on both types of cells coincided in general.
5) The 1st, 2nd, 3rd, 5th, and 10th passages of the Mahoney, LSc. 2ab strains and isolates of poliovirus type 1 were incubated on HeLa cells at 35°C, but few of them changed T-marker.
It seems reasonable to conclude from these tests that HeLa cells are applicable to the T-marker and Wecker tests, as well as MK cells.
