Distinctive characteristics of crude interferon from virus-infected guinea-pig embryo fibroblasts

Modification of immunological responses and clinical disease during topical R-837 treatment of genital HSV-2 infection

R-837, a compound with no in vitro anti-HSV activity, was administered intravaginally to guinea pigs (5 mg/kg every 12 h) for five days beginning 12 h after genital HSV-2 inoculation. Drug treatment reduced vaginal viral replication (P less than 0.0001), completely protected against primary disease and reduced recurrent genital HSV disease (P less than 0.0001). Drug treatment also induced mild fever, weight loss, and decreased water intake. R-837 was a potent interferon inducer, which also induced variable enhancement of cell-mediated cytolytic activity against HSV-2 targets. Less than 36 h of vaginal HSV shedding was observed in animals with R-837 induced early enhancement of HSV-target cytolysis. Compared to placebo, R-837 decreased ELISA and ADCC antibody to HSV-2, but accelerated HSV-2 specific in vitro IL-2 production and peripheral blood mononuclear cell (PBMC) proliferation. R-837 exhibited potent anti-HSV activity in vivo apparently due to cytokine induction and enhancement of cell-mediated responses.

Efficacy of S26308 against guinea pig cytomegalovirus infection

Prophylactic use of antiviral agents against cytomegalovirus (CMV) is particularly indicated for the immunocompromised host because morbidity and mortality due to CMV occur most frequently following immunosuppression. We have evaluated the new Riker compound S26308 for its therapeutic and prophylactic antiviral activity against CMV in guinea pigs. The efficacy of the compound was assessed in vitro in guinea pig embryo cells and in vivo in both immunocompetent and immunocompromised guinea pigs. Guinea pig CMV plaque formation was reduced only in cells treated with S26308 prior to virus infection. The antiviral activity remained even when the compound was removed after virus absorption and was due to neither virus destruction nor inhibition of cell growth. The frequency of viremia was reduced in guinea pigs for which S26308 therapy was initiated 24 h prior to virus inoculation compared with sham-treated animals. This reduction in the frequency of viremia did not prevent virus spread to target tissues but did result in a reduction of the severity of CMV-induced disease in immunocompromised guinea pigs. Low levels of interferon were detected in supernatants of S26308-treated cells, and interferon was detected in the serum of guinea pigs given S26308. These results indicate that S26308 can induce interferon and reduce CMV infectivity in vivo and in vitro when used prophylactically. This antiviral activity, although modest, was accompanied by beneficial effects on CMV-induced morbidity and mortality. Prophylactic use of S26308 in combination with other therapeutic agents may be a useful strategy against CMV infections.

A high-yield chromatographic method for the purification of rat fibroblast interferon to a high specific activity

Rat fibroblast interferon (RfIFN), produced in serum-free media, has been purified 2,000-fold to 88% purity by a simple method that involves only two chromatographic steps: controlled pore glass and phenyl agarose chromatography. Over 70% of the initial activity was recovered. Gel electrophoresis (SDS-PAGE) and silver staining of the purified RfIFN revealed two major bands of RfIFN activity corresponding to Mr of 26,000 and 22,500 daltons, respectively. A very small amount of RfIFN was also recovered from a region of the gel corresponding to a Mr of 18,500. The average specific activity of the purified material was 3.7 X 10(8) U/mg. From these results it can be calculated that the specific activity of homogenous RfIFN is 4.0 X 10(8) U/mg.