Cidofovir for the Treatment of Molluscum Contagiosum Virus

That cidofovir, an acyclic nucleoside phosphonate (ANP), was inhibitory to the replication of poxviruses was first demonstrated by De Clercq et al.. That its active metabolite, the diphosphate, was found to be inhibitory to the molluscum contagiosum (M. contagiosum) DNA polymerase was demonstrated by Watanabe and Tamaki. Twelve different independent observations have then indicated that cidofovir administered intravenously, topically or intralesionally is efficacious in the treatment of M. contagiosum mostly in immunosuppressed patients.

Species-Specific Inhibition of Necroptosis by HCMV UL36

Viral infection activates cellular antiviral defenses including programmed cell death (PCD). Many viruses, particularly those of the Herpesviridae family, encode cell death inhibitors that antagonize different forms of PCD. While some viral inhibitors are broadly active in cells of different species, others have species-specific functions, probably reflecting the co-evolution of the herpesviruses with their respective hosts. Human cytomegalovirus (HCMV) protein UL36 is a dual cell death pathway inhibitor. It blocks death receptor-dependent apoptosis by inhibiting caspase-8 activation, and necroptosis by binding to the mixed lineage kinase domain-like (MLKL) protein and inducing its degradation. While UL36 has been shown to inhibit apoptosis in human and murine cells, the specificity of its necroptosis-inhibiting function has not been investigated. Here we show that UL36 interacts with both human and murine MLKL, but has a higher affinity for human MLKL. When expressed by a recombinant mouse cytomegalovirus (MCMV), UL36 caused a modest reduction of murine MLKL levels but did not inhibit necroptosis in murine cells. These data suggest that UL36 inhibits necroptosis, but not apoptosis, in a species-specific manner, similar to ICP6 of herpes simplex virus type 1 and MC159 of molluscum contagiosum virus. Species-specific necroptosis inhibition might contribute to the narrow host range of these viruses.

Pediatric molluscum: an update

Molluscum contagiosum virus (MCV) is a poxvirus that causes infection in humans that is limited to the cutis and subcutaneous levels of the skin. The virus is transmitted from close associates in settings such as pools, day care, and bathtubs. Pediatric molluscum is common in school-aged children and resolves spontaneously in healthy children. Widespread lesions, complicated by comorbid dermatitis, are expected in children with atopic dermatitis (AD); however, even children without AD can develop dermatitis or signs of inflammation or pruritus. Molluscum is the great mimicker in pediatric dermatology; the morphology of the lesions and overlying rash can make molluscum look polymorphous and similar to other skin illnesses. This article addresses the issue of transmission, course of disease, comorbidities, and therapeutic options, including the gold standard-nonintervention. The decision to intervene is a joint decision among children, parents/guardians, and the practitioner. The first priority should be reduction of symptoms, followed by reduction of spread and then disease remission.

Molluscum contagiosum in a pediatric American Indian population: incidence and risk factors

Background

Molluscum contagiosum virus (MCV) causes an innocuous yet persistent skin infection in immunocompetent individuals and is spread by contact with lesions. Studies point to atopic dermatitis (AD) as a risk factor for MCV infection; however, there are no longitudinal studies that have evaluated this hypothesis.

Methods

Outpatient visit data from fiscal years 2001–2009 for American Indian and Alaska Native (AI/AN) children were examined to describe the incidence of molluscum contagiosum (MC). We conducted a case-control study of patients <5 years old at an Indian Health Service (IHS) clinic to evaluate dermatological risk factors for infection.

Results

The incidence rate for MC in children <5 years old was highest in the West and East regions. MC cases were more likely to have a prior or co-occurring diagnosis of eczema, eczema or dermatitis, impetigo, and scabies (p<0.05) compared to controls; 51.4% of MC cases had a prior or co-occurring diagnosis of eczema or dermatitis.

Conclusions

The present study is the first demonstration of an association between AD and MC using a case-control study design. It is unknown if the concurrent high incidence of eczema and MC is related, and this association deserves further investigation.

[Molluscum contagiosum--a common but poorly understood "childhood disease" and sexually transmitted illness]

Molluscum contagiosum is a viral disease of the skin characterized by discrete, multiple, flesh-colored papules. It is caused by a highly infectious, enveloped deoxyribonucleic acid virus, called molluscum contagiosum virus (MCV). Molluscum contagiosum is very common in children, sexually active adults and immunocompromised patients, especially those who are infected with the human immunodeficiency virus. MCV transmission usually takes place through direct skin-to-skin contact. Infections in childhood are often linked to swimming-pool attendance. Adults are infected usually through sexual contact. An intimate skin-to-skin contact is sufficient for transmission of the virus. In immunocompetent adults, the warts remain in the genital area and adjacent regions of the skin. In children and patients with immunocompromised conditions, however, various regions of the body are usually affected. Therapy of molluscum contagiosum should be undertaken in an individualized manner, a specific treatment does not exist. For the treatment, physical methods such as curettage and cryotherapy, topic acids (e. g., acetic acid) and alkalis (e. g., potassium hydroxide), some other topical agents such as cantharidin and imiquimod, as well as several systemic agents the pharmacological treatments is, however, sparse. Effective prevention is problematic due to the high infectivity of the virus. A vaccine is not available.

Lesions on tattooed skin--a case study

A man, 33 years of age, presented complaining of asymptomatic lumps on the tattooed skin of his right upper arm. The lumps appeared spontaneously 5 months after getting the tattoo. He had no significant past medical or surgical history. On examination, several 3–4 mm shiny, umbilicated papules were seen on the tattooed skin (Figure 1).Tests for human immunodeficiency virus (HIV), hepatitis B virus, hepatitis C virus and syphilis were negative and full blood examination was normal.

Eosinophilic intranuclear inclusion bodies in a melanocytic nevus

We report a case of eosinophilic or hyaline true intranuclear inclusion bodies in a melanocytic nevus. Although intranuclear pseudoinclusions are frequently found in melanocytic nevi, true intranuclear inclusions are rare. The true intranuclear nature of the inclusions in our case was confirmed with ultrastructural examination. With reverse transcriptase in situ polymerase chain reaction (RT in situ PCR) analysis, eosinophilic bodies stained positive for molluscum-specific primers. This result suggests that such inclusions may be related to molluscum viral infection of melanocytes.

The herpesvirus 8-encoded chemokine vMIP-II, but not the poxvirus-encoded chemokine MC148, inhibits the CCR10 receptor

The viral chemokine antagonist vMIP-II encoded by human herpesvirus 8 (HHV8) and MC148 encoded by the poxvirus - Molluscum contagiosum - were tested against the newly identified chemokine receptor CCR10. As the CCR10 ligand ESkine / CCL27 had the highest identity to MC148 and because both chemokines are expressed in the skin we suspected MC148 to block CCR10. However, in calcium mobilization assays we found MC148 unable to block CCR10 in micromolar concentrations in contrast to vMIP-II. (125)I-MC148 was only able to bind to CCR8, but not to CCR10, CCR11, CXCR6 / BONZO, APJ, DARC or the orphan receptors BOB, EBI-II, GPR4, GPR17, HCR or RDC1. We conclude that MC148 is a highly selective CCR8 antagonist conceivably optimized to interfere with NK cell and monocyte invasion, whereas the broad-spectrum antagonist vMIP-II protects HHV8 by blocking multiple receptors.

Death effector domain-containing herpesvirus and poxvirus proteins inhibit both Fas- and TNFR1-induced apoptosis

To identify novel antiapoptotic proteins encoded by DNA viruses, we searched viral genomes for proteins that might interfere with Fas and TNFR1 apoptotic signaling pathways. We report here that equine herpesvirus type 2 E8 protein and molluscum contagiosum virus MC159 protein both show sequence similarity to the death effector domains (DEDs) of the Fas/TNFR1 signaling components FADD and caspase-8. Yeast two-hybrid analysis revealed that E8 protein interacted with the caspase-8 prodomain whereas MC159 protein interacted with FADD. Furthermore, expression of either E8 protein or MC159 protein protected cells from Fas- and TNFR1-induced apoptosis indicating that certain herpesviruses and poxviruses use DED-mediated interactions to interfere with apoptotic signaling pathways. These findings identify a novel control point exploited by viruses to regulate Fas- and TNFR1-mediated apoptosis.