Ernest C. Herrmann

Encephalitis Associated with Herpes Simplex Virus

Excerpt Five patients with fatal encephalitis have come under our observation in a 2-year period. Herpes simplex virus was isolated from the brain in all of these cases. The neurologic picture coul...

Antiviral substances in plants of the mint family (labiatae). I. Tannin of Melissa officinalis.

Summary Tannin-containing fractions from aqueous extracts of Melissa officinalis were prepared by gelatin precipitation, hide-powder adsorption, and lead acetate precipitation and it was found that the tannin recovered from these preparations was the hemagglutination inhibitor for Newcastle disease virus. Tannin prepared by gelatin precipitation showed antiviral activity in tests in eggs and in plaque-inhibition tests with Newcastle disease virus and hemagglutination tests with mumps virus. Aqueous extracts of the melissa plant blocked hemadsorption by parainfluenza viruses 1, 2, and 3. The tannin of this plant appears to have an affinity for myxoviruses of subgroup 2 but has no effect on influenza A and B viruses in hemagglutination and hemadsorption tests. The tannin is not primarily virucidal for Newcastle disease virus; its effect is a neutralization which can be reversed by dilution or by addition of gelatin.

Antiviral Substances in Plants of the Mint Family (Labiatae). III. Peppermint (Mentha piperita) and other Mint Plants.

Summary Extracts of various plants of the mint family (Labiatae) were studied for antiviral activity. Peppermint Mentha piperita extract had antiviral activity against Newcastle disease (NDV), herpes simplex, vaccinia, Semliki Forest, and West Nile viruses in egg and cell-culture systems. It contains a tannin with an affinity for NDV and mumps virus and a nontannin fraction with antiviral effects against herpes simplex virus. Aqueous extracts of sage (Salvia cyprea), marjoram (Origanum majorana), wild thyme (Thymus serpyllum), American pennyroyal (Hedeoma pulegioides), Crea monda (Satureia sp.) and Spanish and French thymes (Thymus sp.) all exhibited some antiviral effects against NDV. The first 6 also exhibited some antiviral effects against herpes simplex. Hyssop (Hyssopus officinalis) extracts had activity against herpes simplex virus while rosemary (Rosmarinus officinalis), horehound (Marrubiutn vulgare), and catnip (Nepeta cataria) extracts were not detectably antiviral. None of these plant extracts produced an antiviral effect superior to that of melissa (Melissa officinalis) extracts. The data suggest the existence of some biochemical relationships among plants of the mint family, especially the presence of a common tannin.

Antiviral Activity of Melissa officinalis (Lemon Balm) Extract.

Summary Hot-water extracts of the plant Melissa officinalis (lemon balm herb), when injected into embryonated eggs, protect them against the lethal action of Semliki Forest, Newcastle, vaccinia, and herpes simplex viruses. Plaques produced by these viruses in chick embryo cell monolayers can be suppressed by applying melissa extract-impregnated antibiotic-sensitivity discs to the agar overlay surface. Injection of 10% gelatin into eggs before or after injection of melissa extract largely eliminates the antiviral effect. Melissa extracts precipitate gelatin and the antiviral activity can be recovered from the precipitate. It is suggested that the active moiety is a tannin or tannin-like polyphenol that perhaps acts at the cell surface.

Antiviral Substances in Plants of the Mint Family (Labiatae). II. Nontannin Polyphenol of Melissa officinalis.

Summary The presence of gelatin did not eliminate the antiviral activity of aqueous extracts of Melissa officinalis against herpes simplex and vaccinia viruses in disc plaque-suppression tests, suggesting that a second, nontannin, antiviral substance was present. By using tannin-free preparations it was found that the nontannin polyphenol fraction produced an antiviral effect against herpes simplex and vaccinia viruses in egg and cell-culture systems. This activity was very similar to that of caffeic acid. It was not clear whether the antiviral effect of either of these materials was exclusively due to a virucidal effect. Preliminary thin layer chromatography revealed the presence of caffeic acid in melissa preparations but at levels that seemed far too low to account for the antiviral effect.

Inhibition of Varicella Virus by 5-Iodo-2'-Deoxyuridine.

Summary Although 5-iodo-2′-deoxyuridine (5-IDU) has some effect on the multiplication of human fibroblasts in tissue culture, it also markedly prevents cytopathic effects of varicella-zoster virus even when added to the tissue culture in concentrations of 5 μg/ml as long as 3 days after challenge with the virus. The compound will inhibit further plaque formation even after cytopathic effects are already evident. Production of plaque-forming virus particles is likewise suppressed by the compound. These findings provide indirect evidence that varicella-zoster virus is a DNA virus, and they suggest that perhaps this compound might find some use in cases of serious human disease produced by this virus.

Gradient Plate Technique Applied to the Study of Antiviral Substances.

Summary The gradient plate technique, originally used in bacteriology, was adapted to the study of virus inhibition by known antiviral compounds, including pyrimidine nucleo-sides, thiosemicarbazones, amantadine, guanidine, and -hydroxybenzylbenzimidazole, all of which produced striking antiviral effects. Reversal of 5-iodo-2′-deoxyuridine (IUdR) activity by thymidine was readily quantified by using this method. The technique was applicable to the bioassay of IUdR and guani-dine and to the ready detection and isolation of IUdR-resistant strains of herpes simplex virus.