Harold E. Renis

Antiviral melanization reaction of Heliothis virescens hemolymph against DNA and RNA viruses in vitro

1. Antiviral activity of Heliothis virescens larval hemolymph was determined using a cytotoxicity/virus inhibition test (TClD50) done in Vero cell tissue cultures. Excellent antiviral activity was found especially against herpes simplex viruses-1 and -2 and also against vesicular stomatitis, parainfluenza-3, coxsackie B3 and sindbis viruses. 2. Prolonged incubation of herpes simplex virus-1 and vesicular stomatitis virus with hemolymph was virucidal and greatly reduced infectivity of the two viruses in tissue culture. 3. Antiviral activity was produced by both normal and immune (vaccinated larvae) cell-free hemolymphs. 4. Antiviral activity against herpes simplex virus-1 could be generated in vitro with hemolymph phenoloxidase or mushroom tyrosinase using four different substrates including tyrosine. 5. Activation of the insect melanization reaction by phenoloxidase was necessary for antiviral activity to occur.

Genital Infection of Female Hamsters with Herpesvirus Hominis Type 2 (HVH-2)

Summary Intravaginal inoculation of female hamsters (40-65 g) with HVH-2 (6 × 105 PFU) results in an infection of 40-67% of the animals. The illness is characterized by vaginitis with discharge, paralysis, and finally death. Washing the vagina with saline 30 min prior to virus inoculation enhances the infection so that 80-100% of the animals eventually die. Virus can be isolated from the vagina within 1-2 days after inoculation. Evidence of infection of the spinal cord is apparent by the third day whereas virus could not be isolated from the brain until Day 5. Attempts to demonstrate virus in whole blood, spleen, kidney, or liver homogenates prepared from infected animals were negative. The excellent technical assistance of E. B. Swynenberg is gratefully acknowledged.

Bropirimine-Induced Embryolethality after Oral Administration to the Pregnant Rat

Oral bropirimine (an immunomodulator shown to induce interferon) was administered to timed-pregnant Sprague-Dawley rats in five experiments utilizing several different dosing schedules. Concentrations of 100, 200, and 400 mg/kg of bropirimine were used. Interferon levels were determined in maternal serum, spleen, and whole embryo extracts and uterine contents were evaluated for survival of the embryos. Maternal toxicity occurred in all experiments as evidenced by dose-related decreases in body weight during the first 24 hr postdosing. Hematoxicology analyses of maternal serum revealed significant decreases in urea nitrogen, potassium, and albumin, along with increases in aspartate transaminase, alanine transaminase, and total bilirubin, in bropirimine-treated dams as compared to the vehicle controls. In addition, the means for maternal thymus weight decreased while the means for spleen weight increased with increasing concentration of bropirimine. As compared to the vehicle controls, interferon titers were high in maternal serum, maternal spleen, and, to a lesser extent, whole embryos, 2 hr postdosing, but had decreased or were below detectable levels 24 hr postdosing. Embryolethality was pronounced (increases in pre- and postimplantational loss) after a single dose (Gestation Day 3, 4, 5, 8, 9, or 10) of bropirimine, as well as after 7 or 8 consecutive days (Gestation Days 6-12 or 6-13) of treatment. Although embryotoxicity never occurred in these experiments in the absence of pronounced maternal toxicity, the pregnant dams never died as the result of bropirimine treatment, whereas the embryos frequently failed to survive.

A hypothesis relating lymphocyte phosphorylation and transport of ara-C (cytarabine) to its antiviral activity.

Abstract A hypothesis is presented which suggests that the antiviral activity of ara-C in man is augmented by the transport of activated ara-C within circulating lymphocytes. The salient features of the hypothesis are the following. First, suggestive evidence is accumulating that ara-C is an effective antiviral agent in man against certain DNA viruses (primarily herpesviruses) after systemic administration. Secondly, ara-C is transported and directed to the site of virus infection by lymphocytes. Third, the small lymphocytes circulating in the blood of man are more active compared with several animal species in phosphorylating (activating) ara-C, and this may be the reason why ara-C is much less effective in animals. Fourth, the antiviral activity of ara-C, which seems to be greater than what might be expected from plasma level studies, may be further augmented because the ara-C is being transported intracellularly and is therefore protected from normal catabolic and excretory processes. Fifth, the non-proliferating circulating lymphocyte can carry this cytotoxic agent safely because ara-C is inhibitory only during the S- (DNA-synthetic) phase of the cell cycle. Finally then, the activated ara-C could be introduced into the virus-infected cell by either normal immunologic cell to cell contact mechanisms or by cell fusion.