Response of cloned progeny of clinical isolates of herpes simplex virus to human leukocyte interferon

Comparison of intramuscular recombinant alpha interferon (rIFN-2A) with topical acyclovir for the treatment of first-episode herpes genitalis and prevention of recurrences

Intramuscular recombinant alpha interferon (rIFN-2A; 9 million IU given for 5 days during a 9-day treatment period) was compared with topical acyclovir in a double-blind, placebo-controlled trial for the treatment of first-episode genital herpes simplex virus (HSV) infection and for subsequent alteration of the frequency of recurrences. rIFN-2A (within 96 h of onset of the first episode) was not superior to topical acyclovir in a well-matched group of 105 patients. The early use of rIFN-2A also did not alter the frequency or severity of genital HSV recurrences within either the first or second 6 months following therapy. Separate analyses by HSV type and by type of infection (primary versus nonprimary) did not change this conclusion. Furthermore, there was significant toxicity associated with rIFN-2A therapy. rIFN-2A is not indicated for the treatment of genital HSV infections.

Sensitivity in vitro of herpes simplex virus isolates to human fibroblast interferon

Sensitivity of herpes simplex virus (HSV) isolates, from patients with recurrent infections, to human fibroblast beta interferon (IFN), was tested in vitro. Among 25 HSV strains, 12 were HSV-1, isolated from facial and labial lesions, and 13 were HSV-2 isolated from genital lesions. Viral sensitivity to IFN was examined on epithelial MB cell line by yield reduction and plaque reduction and close correspondence between the two methods was observed. Most of HSV-1 isolates were in the same range of sensitivity to IFN, while HSV-2 isolates varied in sensitivity and differences approached statistical significance (P = 0.14). No correlation was found between various biological properties, such as plaque size, virulence in baby mice, growth at different temperatures, thymidine kinase activity in the presence or absence of IFN and sensitivity to IFN. Application of beta IFN containing cream reduced clinical symptoms in most of the patients. However, larger numbers of patients should be evaluated in order to conclude whether in vitro sensitivity correlates to clinical improvement.

Interferon susceptibility of herpes simplex virus strains isolated from patients enrolled in clinical trials

Herpes simplex virus type 1 strains isolated from patients who had received interferon in a clinical trial were not more resistant to human leukocyte interferon than strains derived from recipients of a placebo. The susceptibility of herpes simplex virus type 2 strains isolated from herpes genitalis was slightly less than that of herpes simplex virus type 1 strains causing herpes genitalis.

Combined interaction of antiherpes substances and interferon beta on the multiplication of herpes simplex virus

The inhibition of herpes simplex virus type 1 (strain McIntyre) by two anti-herpes substances applied in combination was studied by means of a CPE inhibition method In Vero cell microcultures. The following substances were studied: AraA monophosphate, thymine arabinoside, ethyldeoxyuridine, acycloguanosine (acyclovir). 3-fluorothymidine, phosphonoformic acid. Most substance pairs showed a moderate degree of synergism. Two additive interactions and one case of antagonism was observed. Human fibroblast interferon, combined with the antiherpes substances, showed an additive interaction with AraAMP, but synergism with the others.

Alpha interferon and acyclovir treatment of herpes simplex virus in lymphoid cell cultures

The T-lymphoblastoid cell line CEM, persistently infected with herpes simplex virus type 1, has been used to examine the antiviral efficacy of human alpha interferon and acyclovir, both alone and in combination. Acyclovir and interferon each produced dose-dependent decreases in virus titer at concentration ranges of 1 to 100 microM (approximately 0.225 to 22.5 micrograms/ml) and 10 to 10,000 U/Ml, respectively. Mean reductions in titer of 1.9 and 4.2 log10 PFU/ml were observed with 100 microM acyclovir and 10,000 U of interferon per ml, respectively, on day 10 of treatment. The combination of 100 microM acyclovir and 10,000 U of interferon per ml produced the most rapid fall in virus titer of all regimens examined and elimination of infections virus by day 7. Prolonged treatment (greater than 10 days) with acyclovir or alpha interferon was accompanied by a gradual return of virus titer to control levels despite the continuous presence of drug. Virus preparations isolated from such cultures were tested for antiviral agent sensitivity by a plaque reduction method. Acyclovir-exposed isolates were found to be acyclovir resistant, with 50% inhibitory doses of greater than 200 microM, and to be thymidine kinase deficient. Alpha interferon-exposed isolates were not interferon resistant. These results suggest that, in persistently herpes simplex virus-infected CEM cells: (i) combination treatment with 100 microM acyclovir and 10,000 U of alpha interferon per ml is more effective in reducing virus titer than either agent alone; (ii) prolonged exposure to drug may result in development of resistance by either the virus strain or the host cell system; and (iii) development of acyclovir resistance by herpes simplex virus in lymphoid cells is mediated by thymidine kinase.