Inhibition of herpes simplex virus by synthetic double-stranded RNA (polyriboadenylic and polyribouridylic acids and polyriboinosinic and polyribocytidylic acids)

Spectroscopic study of the interaction between poly-(9-vinyladenine) and single or multistrand RNA

The interaction between poly(9-vinyladenine) (PVAd) and poly[r(U)] was investigated by means of uv, CD, 1H-, and 31P-nmr spectroscopies. The interaction was dependent on the molecular weight of PVAd determined by uv and CD spectroscopies. Based on imino proton nmr, it was clearly found that PVAd formed the complex with poly[r(U)] by complementary hydrogen bonding. The interaction of PVAd with double- and triple-stranded helices of RNA was also investigated by uv melting behavior and 31P-nmr spectroscopy. The results suggested that PVAd could not interact with the double-stranded poly[r(A)].poly[r(U)] but did with the triple-stranded RNA.

Inhibition of herpes simplex virus strains isolated from herpetic keratitis by polyinosinic acid-polycytidylic acid

Fifty strains of herpes simplex virus, isolated from patients with herpetic keratitis, were examined in vitro for susceptibility to polyinosinic acid-polycytidylic acid [poly(I:C)] in the presence of a constant concentration of diethylaminoethyl-dextran. The minimal inhibitory concentration of poly(I:C) for 44 of these strains ranged from 0.0001 to 0.1 mug/ml; for the remaining six strains, the minimal inhibitory concentration stood at 1 to 2 mug/ml. Fifteen isolates from primary infections were more susceptible to poly(I:C) than 35 isolates from recurrent infections. Isolates acquired at different points of a given clinical episode showed similar susceptibilities to poly(I:C). In two patients, isolates from consecutive recurrences of infection exhibited reduced susceptibilities. The implications of the above observations for the therapeutic use of poly(I:C) are discussed.

Antiviral effect of pyran against systemic infection of mice with herpes simplex virus type 2

The immunomodulator pyran markedly protected 5-week-old mice from lethal intravenous infection with herpes simplex virus type 2. The 50% lethal dose was increased almost 100-fold in pyran-treated mice as compared with controls. Although the protection was not as marked in older mice (10 and 16 weeks old), there was a significant increase in mean survival time. When the pathogenesis of herpesvirus disease was monitored in control and drug-treated mice, the effect of pyran was most evident in the spinal cord, where virus was recovered from 20 of 25 control mice and from only 6 of 25 pyran-treated mice. There was also a significant reduction in the titer of virus present, and virus appeared later in the spinal cord of pyran-treated mice than in control mice. The protective effect of pyran was observed only when the drug was administered 24 h before viral challenge, was seen after both intraperitoneal and intravenous injection, and was not due to direct inactivation of the virus.

Herpesvirus hominis infection in newborn mice: treatment with interferon inducer polyinosinic-polycytidylic acid

Intranasal inoculation of newborn mice with Herpesvirus hominis (HVH) type 2 provides a model for disseminated herpesvirus infections of human newborn infants. Treatment of this experimental infection with polyinosinic-polycytidylic acid [poly(I:C)] significantly increased the mean survival time and markedly altered the pathogenesis of the infection. No significant protection against final mortality was observed. Poly(I:C) therapy completely inhibited detectable viral replication in all target organs tested except the brain. In the brain there was a 2-day delay in the onset of viral replication in treated animals, which correlated with the 1- to 2-day increase in mean survival time. In general, the control of HVH replication occurred in those target organs in which poly(I:C)-induced interferon was detectable. The failure of poly(I:C) to alter the final mortality of newborn mice infected with HVH appears to be primarily due to the lack of sufficient levels of interferon induced in brain tissue and the failure to prevent viral replication in this critical target organ.

Observations of cattle, goats and pigs after administration of synthetic interferon inducers and subsequent exposure to foot and mouth disease virus

Polyriboinosinic-polyribocytidylic acid (poly [rI.rC]) was administered intravenously to 11 cattle and 13 goats in doses of 0.25 to 4.0, and 1.0 to 5.0 mg/kg, respectively. Subsequent exposure of these and untreated control animals to foot and mouth disease virus (FMDV) failed to demonstrate any differences in either the course or severity of the disease. Serum interferon was detected in cattle one hour after the intravenous administration of poly (rI.rC). Six pigs given 4, 20, or 100 mg/kg of itaconic-acrylic acid copolymer (IAA, HMW) intraperitoneally reacted clinically the same as six untreated control pigs after contact exposure to FMDV. Three pigs given 50, 100, or 200 mg/kg of divinyl ether-maleic anhydride copolymer (DVE/MA, pyran) intraperitoneally similarly failed to show any difference in clinical reaction from three untreated control pigs after intranasal instillation of FMDV. Three pigs given 100, 200 or 400 mg/kg of DVE/MA intraperitoneally developed rapid diffuse peritonitis causing the death of one in 48 hours.

Antiviral activity and side effects of polyriboinosinic-cytidylic acid complexes as affected by molecular size

The decrease of the molecular size of poly(I.C) to less than 10(6) decreases its ability to induce interferon, protect mice against virus, or enhance the immune response. Immune adjuvant activity appeared more sensitive to molecular weight than the other protective activities. The composition of the complex-the molecular size of the individual homopolymers when one was large and the other small-did not affect antiviral activity; the activity of a complex made from large poly(I) and small poly(C) was similar to one made from small poly(I) and large poly(C). Molecular size of the complex did not profoundly alter the side effects of poly(I.C). At 2 mg/kg, none of the complexes markedly altered phagocytic function. Only the largest complex sensitized the mouse to endotoxin. However, all of the complexes studied profoundly inhibited drug metabolism by the liver microsomal enzymes between 24 and 72 hr after their inoculation. Decreasing the molecular weight did not alter this inhibition.

Role of adrenal cortical function in toxicity of polyriboinosinic-polyribocytidylic acid and its component homopolymers

Adrenalectomized rats are 1000 times more sensitive to lethal effects of the double-stranded complex polyriboinosinic.polyribocytidylic acid than intact rats. They are protected from such lethal effects by corticosterone. The complex can rapidly induce diffuse, severe necrosis of villous epithelium in small intestine without damage in crypts. Injection of the individual homopolymers, polyriboinosinic acid and polyribocytidylic acid, separately but in rapid succession is at least as lethal as injection of the complex.