Recently several reports have appeared on the plaque assay procedures of measles virus, but all these methods have succeeded only by use of primary monkey kidney cell cultures and overlay media such as plasma clot or bovine amniotic fluid.
In order to simplify the technique or to suit for routine work, experiments were cat ried out with stable cell lines for plaque assay culture and obtained the following results:
1) When the “Sugiyama” strain of measles virus, adapted to FL cells, was plated in HEp-2, FL, HeLa and KB cell monolayers and oberlaid with Yeast extract-Lactalbumin hydrolysate-Earle's balanced salt solution (YLE) agar media and keeping all oberlaid plates at 36°C, we could easily obtain small clear plaques. Thus, a plaque assay method for measles virus has been developed useing YLE-agar oberlay medium.
2) The optimal condition was found in the YLE-agar oberlay medium (pH 7.6) of 0.5% NaHCO₃, 10% serum and of 1.1-2.2% agar (about 3m1 per 50-m1 bottle).
3) Of our four human cell cultures, we found HEp-2 and KB cell cultures to possess the highest plating efficiency of measles virus under the same conditions, which were followed by FL and HeLa cell cultures in order.
4) In monolayers infected with appropriate dilutions of measles virus, there appeared small but distinct plaques on the 5th day. The average diameter of plaque was about 2-3 mm. Plaque number increased gradually up to the 10th day, but not increased thereafter, leaving the countable same number possibly up to the 20th day.
5) When the same input dose of measles virus was used, the constant plaque number appeared increasingly up to the 4th day in the cell sheet which was taken in the logarithmic growth phase, but in the contrary its plaque number rapidly decreased in the decline phase.
6) The plaque assay of strains of measles virus, “Edmonston”, FV₄₉ (FL passage 49 of “Toyoshima” strain) and KB1.4 (KB passage 14 of FL-adapted “Toyosma” strain), which were all adapted to stable cell lines, showed almost the same results as that of “Sugiyama” strain.

View full abstract

For the purpose of obtaining a more precise assay for potency of vaccine lymph, . Groth's method described in the “Minimun Requirement of Biologic Products” was reinvestigated.
The result revealed that this method was just able to detect fourfold difference in virus content but absolutely not twofold difference.
However, by use of minimum possible amount of serial dilution of the lymph, such as 0.05 ml in place of 0.2 ml as noted in the Minimum Requirement, a little more minute difference of potency could be traced.
In addition to this, it was established by the present investigation that we are able to detect the minute difference as “twofold”, when the reading of the vaccinial responses on the shaved skin of rabbit was conducted in an early stage, for instance, on the 4th day after the inoculation, independently of 7-day observation period as described in the Minimum Requirement.
In view of these observations, it appears that the Groth's original method, which appears to lay not much stress on the highest dilution capable of causing a positive reaction, as well as the recommendationn by the Commission to take definitely positive reaction in 72 hours following the inoculation of 0.1 ml of 1/1, 000 dilution of lymph, is more adequate as compared with the modified Groth's method as now employed in this country.

View full abstract

Taocin was perorally administered, 0.8-1.2g (adult dosis) 4 times daily for 5 days to dysenteric patients and carriers (52 cases in total) admitted in the Toshima Hospital form August 1963 to January 1964.
The results were as follows:
1. Clinical effects
Days needed for decrease of stool numbers, subsidance of fever, disappearance of blood and recovery to solid stool were in 18 cases of acute dysentery on an average 3.0, 2.3, 3, 7 and 4.1 days respectively, which are a little longer than average days needed for control of 15 cases due to sensitive strains with Tetracycline.

View full abstract