Bosko Postic

Virucidal effect of certain chemical contraceptives on Type 2 herpesvirus

The virucidal effect of several chemical contraceptives was investigated and the findings are rrported. The supension of Type 2 herpes simplex virus, containing 10(6) to 10(7) tissue culture infectious doses per 0.1 ml., was inactivated on exposure to five different chemical contraceptives. For quantitative estimates of virucidal effect, 10 per cent solutions of these chemical contraceptives were tested with an exposure time of 10 minutes at room temperature. The methods for determination of residual infectivity included both virus assays in cultures of Vero cells and human embryo fibroblasts, as well as the intracranial inoculation of mice. Virus infectivity decreased 1,000- to 10,000-fold after contact with chemical contraceptives, indicating a substantial virucidal effect.

Inactivation of clinical isolates of Herpesvirus hominis, types 1 and 2, by chemical contraceptives.

Two chemical contraceptives were examined for virucidal effects against four strains each of Herpesvirus hominis, type 2 and 1. Seven of the strains represented recent clinical isolates; one strain was a type 2 prototype. Either psermicide reduced the infectivities ofall eight viruses after contact for 10 minutes at room or body temperature. The new spermicide-germicide, compound A, produced an antiviral effect at the low concentration of 0.05%, whereas the commercially available Preceptin was effective at 5%, but not at 0.5%. The substantial loss of viral infectivity was due to direct inactivation of virus by the spermicides and was not secondary to cytotoxicity or induction of interferon in the cell cultures used for the assay. These in vitro findings hold primse for the interruption of the sexual transmission of H. hominis.

Effects of cortisol and adrenalectomy on induction of interferon by endotoxin.

Summary The administration of 1 to 5 mg of cortisol to 1 kg rabbits markedly suppressed interferon production by E. coli endo-toxin. Single doses of cortisol, up to 25 mg, did not decrease circulating interferon levels following inoculations with Newcastle disease virus. This type of interferon was only partially suppressed with multiple injections of 250 mg. Thus, administered cortisol inhibited more readily the production of endotoxin-in-duced interferon than the virus-induced counterpart. Adrenalectomy markedly potentiated the production of interferon by endotoxin. Adrenalectomized rabbits inoculated with endotoxin produced serum interferon to a mean titer of 1:388, while the mean titer in control animals was 1:28, suggesting that endogenous steroids suppress the interferon esponse to endotoxin. Mrs. Linda Carcione offered excellent technical assistance. One of us (Miss Catherine DeAngelis) was a recipient of a summer research fellowship under NIH grant 5416-05.

Effect of Puromycin on Virus and Endotoxin-Induced Interferonlike Inhibitors in Rabbits.

Summary Puromycin was found to inhibit interferon formation in rabbits induced by Sindbis virus. It did not inhibit the induction of an interferonlike inhibitor by bacterial endotoxin. It is suggested that the latter inhibitor is present in rabbits mainly in a preformed state and its release apparently does not require new protein synthesis. On the other hand, the production of the virus-induced interferon in rabbits requires such metabolic function.

Susceptibility of Clinical Isolates of Cytomegalovirus to Human Interferon

Human cell culture-derived interferon was shown to inhibit human cytomegalovirus in vitro. A prototype strain, Davis, and six clinical isolates of cytomegalovirus were tested. All six isolates showed uniform susceptibility to interferon, exceeding that of the Davis strain by two- to fourfold. The latter virus was found to be 32 to 4 times less susceptible than the sensitive indicator, vesicular stomatitis virus. However, the laboratory finding of susceptibility to an antiviral material may not relate to its clinical effectiveness.

Effect of Ribavirin on Murine Cytomegalovirus Infection

Ribavirin (1-β-d-ribofuranosyl-1,2,4-triazole-3-carboxamide), a new synthetic nucleoside, inhibited murine cytomegalovirus in cell culture. This was shown by the inhibition of viral cytopathic effect and plaque formation, as well as reduction in the yield of virus. Despite this in vitro antiviral effect, ribavirin did not protect mice from mortality produced by a high inoculum of cytomegalovirus. When a lower inoculum was used to initiate a chronic infection, the administration of ribavirin for 9 days had no effect on the titer of cytomegalovirus in the salivary gland, kidney, liver, and spleen. Thus, ribavirin was ineffective in the treatment of both acute and chronic murine cytomegalovirus infections.

EFFECT OF POLY I: C IN MICE INJECTED WITH JAPANESE B ENCEPHALITIS VIRUS *

The p rophy lac t i c e f f e c t i v e n e s s of i n t e r f e r o n inducers given t o animals p r ior t o i n f e c t i o n wi th a v i r u s is now w e l l known1. Severa l workers r epor t ed t h a t such inducers , when adminis te red s h o r t l y a f t e r i n f e c t i o n , mediated p a r t i a l p r o t e c t i o n from systemic and l e t h a l v i r a l d i seases . 2-4 These i n v e s t i g a t o r s used v i r a l , fungal , and more r e c e n t l y a s y n t h e t i c inducer of i n t e r f e r o n , the mul t i s t randed polyr ibonucleo t ide comple o n s i s t i n g of i n o s i n i c and c y t i d y l i c a c i d s (poly 1 : C ) . ‘ t g However, v i r u s e s n o t pathogenic f o r man and i n most i n s t ances introduced by an unnatura l , i n t r a p e r i t o n e a l r o u t e w e r e u t i l i z e d . This r e p o r t desc r ibes the p r o t e c t i v e e f f e c t of po ly I : C adminis tered t o 4-5 week o ld m i c e be fo re and a f t e r i n j e c t i o n w i t h an important human pathogen, Japanese B e n c e p h a l i t i s v i r u s ( J B E ) . The r o u t e of v i r u s inocu l a t i o n was subcutaneous, s imula t ing

Cross Plaque Neutralization of Two Antigenically Closely Related Dengue Viruses (Type 2 New Guinea C and TH-36)

,he n a t u r a l l y occurr i n g t ransmiss ion by a mosquito b i te . Varying dosages of JBE v i r u s w e r e i n j e c t e d r e s u l t i n g i n e i t h e r f a t a l o r t r a n s i e n t i n f e c t i o n .

Introduction of Pseudomonas Aeruginosa into a Hospital via Vegetables

Summary Dengue type 2, New Guinea “C” virus, from a case of classical dengue fever was compared with dengue TH-36, an agent antigenically closely related to it but isolated from a case of hemorrhagic fever. Cross neutralization tests by the plaque method were performed in duplicate with essentially duplicate results. These were plotted and the 50% serum end points were determined. Relative potencies for homologous and heterologous serum-virus combination were calculated. Significant differences in degrees of neutralization of the two viruses were obtained, the homologous serum and virus resulting in the highest percentage plaque reduction at every serum dilution in each experiment. It is concluded that these two viruses differ antigenically as demonstrated in relatively precise quantitative tests, confirming previous differences shown by complement fixation, immunodiffusion, and immunoelectrophoresis.

Introduction of Pseudomonas aeruginosa into a hospital via vegetables.

[This corrects the article on p. 567 in vol. 24.].