High conservation of herpes simplex virus UL5/UL52 helicase-primase complex in the era of new antiviral therapies

Efficacy and Safety of Amenamevir, a Helicase-Primase Inhibitor for the Treatment of Acyclovir-Resistant Herpes Simplex Virus 1 Keratitis

PURPOSE

The purpose of this study was to describe the efficacy and tolerance of amenamevir (AMNV), an inhibitor of the viral helicase-primase, for the treatment of recalcitrant herpes simplex keratitis (HSK) caused by acyclovir-resistant (ACVR) herpes simplex virus 1 strains.

METHODS

In this retrospective case series, 6 consecutive patients with HSK caused by an ACVR herpes simplex virus 1 strain with a failure of conventional antiviral therapy were included after having been treated with AMNV (there was no control group of comparable patients for whom previous treatment would have been continued despite its inefficacy). Medical files were assessed for clinical data including reason(s) for AMNV introduction (frequent recurrences despite appropriate preventive antiviral treatment and/or clinical resistance to suppressive antiviral treatment of an ongoing clinical relapse), genotypical resistance to herpes simplex virus 1 documentation, immune status, clinical types and number of HSK episodes before and during AMNV treatment, adverse effects observed during AMNV treatment, and best corrected visual acuity.

RESULTS

Of 6 patients, 4 (66%) did not experience a single recurrence during AMNV therapy while 2 others had recurrences (1 over 24 months of treatment and 2 over 23 months, ie two-fold less frequently than with conventional preventive treatment). On the overall history of these 6 patients, AMNV appeared to be associated with a reduction in HSK recurrences, with a mean of only 0.02 ± 0.04 episodes/month during follow-up under AMNV as compared to 0.14 ± 0.04 episodes/month in the year preceding AMNV introduction (P = 0.03). Improvement in vision acuity was also observed (mean best corrected visual acuity 0.17 ± 0.12 logarithm of the minimum angle of resolution at the end of follow-up vs. 0.30 ± 0.35 before AMNV onset), albeit nonsignificant probably due to the limited number of patients (P = 0.38). Neither clinical nor biological adverse effects were observed while under AMNV during the follow-up (16.5 ± 5.8 months).

CONCLUSIONS

Although there was no control group, AMNV may be a valuable option to reduce ACVR HSK recurrences.

Recent advance in management of herpes simplex in Japan

Herpes simplex, a common infection caused by the herpes simplex virus (HSV), is transmitted through contact of the skin/mucous membrane and establishes latency in the sensory ganglia for the rest of the life of the host. HSV occasionally reactivates and forms blisters around the lips or genitalia in some patients. Repeated overt symptoms, and, much more frequent, subclinical reactivation in the mucosa, make the host retain anti-HSV immunity continuously, resulting in maintaining steadily elevated antibody titer at any point after infection. Clinical symptoms differ in primary infection and recurrence. Primary infections sometimes manifest as severe symptoms such as fever and lymphadenopathy in addition to blisters/erosions of the skin, gingiva, lips, and oral mucosa, while recurrent herpes is generally mild. Diagnosing typical herpes simplex is not difficult, but when the course and manifestations are typical, definitive tests to identify HSV infection are limited since serology is not useful except with primary infection. For treatment, safe and effective oral antiviral drugs are available. Patient-initiated therapy is a new method of administration labeled in Japan. Amenamevir, an inhibitor of viral helicase primase, is available in Japan and labeled in addition to herpes zoster. These new diagnostic and therapeutic tools should be used for better management of herpes simplex.

High conservation of varicella-zoster virus helicase-primase complex, the target of the new antiviral drug amenamevir

Varicella-zoster virus (VZV) resistance to current antiviral drugs, that all target the viral DNA polymerase, represents a growing concern, notably among immunocompromised patients. Amenamevir, a novel antiviral that inhibits the VZV helicase-primase (HP) complex, is approved in Japan for the treatment of herpes zoster. In this study, we describe the low natural polymorphism of VZV HP complex (interstrain identity >99.7% both at nucleotide and amino acid levels) among 44 VZV clinical isolates. This work enabled to settle the maps of natural polymorphisms of VZV HP complex and to provide the genotypic tools for the monitoring of the emergence of VZV resistance to amenamevir in patients.

Herpes Genitalis: Diagnosis, Treatment and Prevention

Herpes genitalis is caused by the herpes simplex virus type 1 or type 2 and can manifest as primary or recurrent infection. It is one of the most common sexually transmitted infections and due to associated physical and psychological morbidity it constitutes a considerable, often underestimated medical problem. In addition to providing the reader with basic knowledge of the pathogen and clinical presentation of herpes genitalis, this review article discusses important aspects of the laboratory diagnostics, antiviral therapy and prophylaxis. The article is aimed at all health-care workers managing patients with herpes genitalis and attempts to improve the often suboptimal counselling, targeted use of laboratory diagnostics, treatment and preventive measures provided to patients.

Optimal management of genital herpes: current perspectives

As one of the most common sexually transmitted diseases, genital herpes is a global medical problem with significant physical and psychological morbidity. Genital herpes is caused by herpes simplex virus type 1 or type 2 and can manifest as primary and/or recurrent infection. This manuscript provides an overview about the fundamental knowledge on the virus, its epidemiology, and infection. Furthermore, the current possibilities of antiviral therapeutic interventions and laboratory diagnosis of genital herpes as well as the present situation and perspectives for the treatment by novel antivirals and prevention of disease by vaccination are presented. Since the medical management of patients with genital herpes simplex virus infection is often unsatisfactory, this review aims at all physicians and health professionals who are involved in the care of patients with genital herpes. The information provided would help to improve the counseling of affected patients and to optimize the diagnosis, treatment, and prevention of this particular disease.