It has been found that soluble guanidine salts show an antiviral effect on poliovirus and on some other enteroviruses. The activity was first detected in a cell culture screening system when the guanidine salt of hydroxyaminomethylene malononitrile inhibited the cytopathic effect of poliovirus in cell cultures. The studies were extended to various in vivo experiments in which the suggestive therapeutic activity of guanidine salts was again observed in monkeys infected with poliovirus. While these drugs cannot be considered for use in human disease because of severe toxicity, it is significant that potential antiviral compounds detected by the cell culture test show in vivo activity and point to the validity of such direct chemotherapeutic trials.

This is a report on a new multiple antigen containing poliomyelitis vaccine in combination with diphtheria and tetanus toxoids and pertussis vaccine. When given to children aged from two months through five years, a satisfactory antibody response was induced.

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The effectiveness of the adenovirus vaccine inactivation process in destroying the tumorigenic potential for hamsters of adenoviruses, simian virus 40 (SV-40), and adenovirus-SV-40 hybrids was studied. Baby hamsters injected with untreated virus and with samples subjected to the complete inactivation process and to portions of the process were observed for tumor development for periods in excess of 300 days. Over 20,000 hamsters were injected. From 1 to 7 hr of exposure to formaldehyde at a concentration of 0.031 m at 37 C was sufficient to destroy the tumorigenicity observed in the nontreated preparations. Since the inactivation process included 48 hr of exposure at 37 C to 0.031 m formaldehyde plus treatment with ultraviolet (UV) and with β-propiolactone (BPL), it was concluded that the process has a large margin of safety. Adenovirus isolates free from tumorigenic potential are difficult, if not impossible, to obtain. Therefore, a proven inactivation process appears to provide the best assurance for obtaining adenovirus vaccines free from such potential. Data presented suggest that the tumorigenic property of the viruses studied might be independent of the infectivity of the preparation. The tumorigenic property was found to be highly susceptible to formaldehyde, but less sensitive to BPL or UV treatment. In contrast, treatment with UV or BPL decreased viral infectivity more readily than tumorigenicity. The three-stage inactivation process (formaldehyde, UV, and BPL) inactivated both tumorigenicity and infectivity.