Virucidal activity of retinal

Recurrent herpes labialis during isotretinoin therapy: is there a role for photosensitivity?

Isotretinoin (13-cis-retinoic acid) is one of the synthetic retinoids derived from vitamin A. Vitamin A derivatives demonstrate virucidal activity, both in vivo and in vitro. Isotretinoin has been used for the treatment of recurrent herpes simplex with encouraging results. However, we present a case with frequent attacks of herpes labialis during isotretinoin therapy for acne, who had a marked decrease in frequency of recurrences following strict use of sunscreens.

Herpetic whitlow during isotretinoin therapy

Isotretinoin is an extremely valuable drug that is occasionally associated with well-known mucocutaneous side-effects, including cheilitis, retinoid dermatitis, palmoplantar desquamation, and photosensitivity. Paronychia has been reported rarely: only two prior cases of herpes simplex infections associated with isotretinoin have been previously reported. We present the first known case of herpetic paronychia occurring in an atopic patient while on isotretinoin therapy for acne.

Clinical observations, virologic studies, and treatment trials in patients with epidermodysplasia verruciformis, a disease induced by specific human papillomaviruses

We have studied 11 patients with the papillomavirus-induced disease epidermodysplasia verruciformis (EV). Clinical diagnostic features are widespread, long-lasting, pityriasis versicolor-like macules and flat, wart-like papules, both usually occurring in early childhood, with the subsequent development in the third decade of multiple skin cancers of the Bowenoid in situ and squamous cell types, primarily in sun-exposed skin. Virologic studies using the methods of immunofluorescence microscopy, restriction endonuclease analysis, and DNA blot hybridization have shown benign lesions to be associated with one or several types of the human papillomaviruses (HPVs) specifically associated with EV (at least 15 types recognized on the basis of sequence homology studies of molecularly cloned genomes). Skin cancers in these patients were associated with the genomes of either HPV-5, HPV-8 or HPV-14, suggesting that these three viruses are potentially oncogenic. A genetic factor appears to play a role in the pathogenesis of EV, since 5 of our patients were children of consanguineous parents and 2 had siblings also suffering with EV, suggesting a recessive inheritance pattern. Treatment of 4 EV patients with an oral retinoid resulted in partial temporary improvement of benign lesions, and the treatment of 2 patients with intralesional interferon injections into multiple Bowenoid cancers in situ has resulted in the disappearance of these lesions. Finally, EV serves as a model for studying the interplay of oncogenic viruses, genetic and immunologic factors, and sunlight in the production of skin cancer in humans.

The effects of retinoids on the replication of herpes simplex virus type 1

Topical treatment of primary herpetic keratitis with 0.25% retinoic acid was effective in significantly diminishing the severity of epithelial lesions in rabbits. Antiviral activity against herpes simplex virus type 1 was also demonstrated in cell culture. Retinoic acid treatment of virus particles for 24 hours had no effect on the infectivity of the virus. At effective antiviral concentrations in cell culture, retinoic acid had toxic action on two different cell lines as detected by an increase in cellular generation time or inhibition of DNA synthesis. Topical instillation of retinoic acid into the eyes of rabbits at the effective antiviral dose (0.25%) had no inhibitory effect on corneal wound closure but did reduce the rate of incorporation of thymidine into DNA by 27%. These studies suggest that although retinoic acid may inhibit the replication of herpes simplex virus type 1, it is difficult to distinguish antiviral effects from anticellular effects.

Photochemical destruction of the virucidal activities of retinoids and unsaturated fatty acids

Photochemical damage either to retinoids by near-ultraviolet radiation or to unsaturated fatty acids by near-ultraviolet radiation in the presence of a hydrophobic photosensitizer destroys the virucidal activities of the compounds, as determined by studies on the enveloped bacteriophage ø6.

Complement-fixing antibody to the AG-4 antigen in herpes simplex virus type 2-infected patients

Sera collected from confirmed herpes simplex virus type 2 (HSV-2) patients were found to be devoid of complement-fixing antibody to the AG-4 antigen at the time of the herpes lesion outbreak in 10 out of 13 cases. However, 1 to 4 weeks after HSV-2 lesion appearance, 28 out of 30 patients acquired complement-fixing antibody to the AG-4 antigen. The sera of these patients contained immunoglobulin M antibody activity and the ability to immunoprecipitate a 160,000-molecular weight early HSV-2 antigen (the AG-4 antigen). Also, these sera were used to show that a variety of anti-herpes virus compounds had a negligible effect on AG-4 production in HSV-2-infected HEp-2 cells. The majority of the compounds tested (including acycloguanosine and phosphonoformate) are known to inhibit late antigen production, suggesting that the AG-4 antigen is an early antigen. It is probably an immediate early antigen (alpha) as it is formed in the presence of cycloheximide and actinomycin D, a treatment which is used to accumulate alpha proteins.

Mechanism of virucidal activity of retinoids: protein removal from bacteriophage phi 6 envelope

The mechanism of the potent virucidal activity of retinol (vitamin A) and retinal (vitamin A aldehyde) was investigated for the interaction of these compounds with a model system enveloped virus, bacteriophage phi 6. The retinoids bind to and inactivate phi 6 without causing large-scale disruption of the virion. Inactivated virions have completely lost the ability to adsorb to host bacteria due to the loss of a viral envelope protein necessary for adsorption.