Jacob Fong

Stability of Vesicular Stomatitis Virus at Varying Hydrogen Ion Concentrations

Discussion and Summary The present results are in conformity with the data of Galloway and Elford5 concerning the instability of vesicular stomatitis virus at pH values of 4.0 or less. The use of more sensitive experimental hosts and determination of 50% mortality endpoints, however, showed that in-activation of virus was achieved only at pH 2.0. Extension of studies beyond the pH value of 9.6 reported by Galloway and Elford (5) revealed the striking resistance of virus to inactivation by alkaline environments. It would appear that the wide range of stability of vesicular stomatitis virus may render it a likely prospect for purification by means of the ion exchange resins.

Response of Peritoneal Exudate Cells to Brucella melitensis. Influence of Nature of Inflammatory Irritant.

Conclusion Studies on mononuclear cell responses to B. melitensis require that attention be paid especially to the nature of inflammatory agent itself when interpreting behavior of the mononuclear cell. The inflammatory substance may so alter mononuclear response as to reverse cytolytic susceptibility of monocytes from normal and immunized animals.

Interference in Cortisone-Treated Hosts.∗

Discussion and Summary The results reported herein have shown that prior injections of cortisone in embryonated eggs subsequently given minimal completely interfering doses of inactivated virus followed by challenge virus resulted in yields of viral hemagglutinins which were 7- to 10-fold greater than that found in untreated eggs. All 3 concentrations of cortisone (2.5, 5 and 7.5 mg) utilized in these experiments appeared to be equally effective in this respect. An enhanced growth of influenza viruses in cortisone-treated eggs has been described previously (4), and the viral concentration of pooled allantoic fluids from cortisone-treated eggs was shown to be 123 to 155% of the viral concentration of control eggs (for influenza A virus). In the interference experiments reported in this paper, the yield of virus in cortisone-treated eggs was 700 to 1000% of the yield in untreated embryos. In view of this discrepancy in the increased yields of virus in the two reports, it would appear that enhancement of reproduction of challenge virus in residual free cells not blocked by interfering virus was not the sole determining factor in the increased yield of virus reported in this paper.

Interaction Between the Soluble Antigen of PR8 and NWS Virus.

Summary The soluble antigen of PR8 virus was interacted in ovo with NWS. The passaged allantoic fluids were doubly neutralized by anti-PR8 and anti-NWS sera, Second passage of these doubly neutralizable particles resulted in a loss of this character. The hypothesis was presented that the doubly neutralizable particles were the result of phenotypic mixing when NWS virus in some way brought about the “maturation” of the intranuclear PR8 soluble antigen.

Response of Normal and Immune Histiocytes of Various Animal Species to Infection by Brucella melitensis

Summary Inflammatory-induced peritoneal histiocytes of rabbit, guinea pig and monkey, both normal and immunized, respond to the cytotoxic action of parasitizing brucella within 24 hours. Normal cells undergo about 30% loss whereas immune cells resist completely the cytotoxic action for at least 96 hours and retard intracellular multiplication for at least 144 hours. Cells of rabbits, guinea pigs, and monkeys react alike in these respects. The cellular immunity produced by the Rev I strain of B. melitensis was also operative against virulent B. suis.

Interaction of Lysates of Histiocytes and Tubercle Bacilli.

Summary Cell lysates derived from peritoneal histiocytes of normal and BCG-immunized rabbits or guinea pigs had no demonstrable direct effect on the morphology, neutral red binding capacity, viability or cytotoxic activity of virulent and attenuated strains of Mycobacterium tuberculosis. Histiocytic lysate in combination with Tween 80 was found to be bactericidal for strains of tubercle bacilli but not for a strain of Escherichia coli or a strain of Staphylococcus aureus. The mechanism of this activity appeared to be due to the enzymatic degradation of Tween 80 by histiocytic lipases with the formation of oleic acid. A similar antimycobacterial activity was manifested in mixtures of histiocytic lysates with crude lipid extracts of normal rabbit serum and with lipemic rabbit serum. No difference in activity was found between cell lysates prepared from histiocytes of normal and BCG-immunized rabbits or guinea pigs.

Inactivation of Virus By Mustard at Varying Hydrogen Ion Concentrations.

Summary A more complete destruction of virus occurred at acid reactions (pH 6.2) as opposed to alkaline reactions. The results with 5 × 10−3 M mustard also indicated that at alkaline reactions destruction of viral infectivity was completed during the first half minute of mustard-virus interaction. In contrast, at pH 6.2 the action of mustard upon virus extended beyond this half minute and led to complete inactivation of virus which survived the initial period of reaction. 2. A comparison of the interfering capacity of virus inactivated with 5 × 10−3 M mustard at pH 8.0 with that of virus treated with 5 × 10−4 M mustard at pH 6.2 revealed a marked interfering effect for the latter. This observation would appear to suggest a convenient procedure for preparation of interfering suspensions of virus for studies of the interference phenomenon.

Effect of Sodium Thiosulfate Upon Mustard-Virus Interaction.∗

Discussion and Summary The present studies would appear to indicate that the rate of reaction of mustard with virus was extremely rapid and that there were chemical groups in influenza virus which rendered them highly susceptible to mustard action. The rapidity of reaction at room temperature was attested by the observation that the greatest portion of the viral population was inactivated during the first minute of mustard-virus interaction. The inability of sodium thiosulfate, a substance reputedly having marked affinity for mustard molecules, to influence the course of events during the first minute of reaction seemingly supported the second of the above premises; presumably thiosulfate failed to compete successfully with virus for the molecules of mustard, thus accounting for the rapid initial destruction of virus. The partially “protective” action of thiosulfate upon destruction of virus by mustard, as reported herein, was confined to events after the first minute of reaction, and was probably related to a tardy combination of thiosulfate and mustard molecules.

Effects of Interfering Virus and RDE upon Development of Toxic Reactions.

Discussion and Summary The results reported in this paper have shown that prior injections of inactivated interfering virus or RDE into mouse brain resulted in a marked reduction in the incidence of toxic episodes usually associated with intracerebral administrations of concentrated suspensions of influenza viruses. Intracerebral injections of RDE failed to prevent toxic manifestations, however when virus was introduced by an intravenous route. The somewhat greater efficiency of RDE in suppression of toxic manifestations. as compared with inactivated virus, may possibly be a reflection of its position in the receptor gradient,. The fact that both inactivated interfering virus and RDE proved effective in protection of animals against toxic doses of virus introduced into the central nervous system might appear to suggest that intimate contact between virus and susceptible cell was essential for development of toxic reactions. If union of virus and cell is indispensable, it is apparently a fairly rapid process. for injection of RDE two hours after toxic virus failed to modify the incidence of toxic reactions.

Initial Stages of Mustard Action upon Influenzal Toxicity and Infectivity.

Summary 1. Sodium thiosulfate in concentrations of 0.2 M or less produced no observable effects upon viral toxicity and infectivity. 2. Intracerebral inoculation of 0.075 M or less of sodium thiosulfate was well tolerated by mice. 3. Admixture of 0.1 M sodium thiosulfate with 5 × 10-4 M cyclo mustard resulted in detoxification of the latter. 4. A possibly greater rate of destruction of viral toxicity by mustard, as opposed to viral infectivity, seemed to occur in the early stages of mustard-virus interaction. 5. Inactivation of viral toxicity by mustard proved complete, but the loss was not demonstrable in the viral progeny derived from eggs infected with one ID50 of mustard-treated virus.