Virus-specific and anticellular antibodies in molluscum contagiosum

ELISA for Molluscum Contagiosum Virus

Molluscum contagiosum virus (MCV) is a common skin pathogen of children and young adults. Infection with MCV causes benign skin tumors in children and young adults and is mostly self-limiting. In contrast to orthopoxviruses, MCV infections tend to take a subacute clinical course but may persist for up to 12 months. Current numbers for MCV seroprevalence in different geographical areas are based on a variety of historical serological methods from complement fixation assays to MCV ELISAs based on purified MCV virions and MC133 antigen expressed in a Semliki Forest Virus expression system. A standardized ELISA for the assessment of MCV seroprevalence would be useful to determine global MCV seroprevalence. The methods described show that polypeptides derived from MCV open reading frames MC084 (residues V123 to R230 and V33 to G117), mc133 (residues M1 to N370), and glutathione S-transferase (GST)-H3L (residues I142 to W251) expressed in E. coli RIL+ as GST fusion proteins can be used to assess antibody binding in a GST capture ELISA. We show how the ELISA can be used to screen a panel of patient sera previously characterized with the mc084 V123-R230 ELISA. © 2017 by John Wiley & Sons, Inc.

Seroprevalence of Molluscum contagiosum virus in German and UK populations

Molluscum contagiosum virus (MCV) is a significant but underreported skin pathogen for children and adults. Seroprevalence studies can help establish burden of disease. Enzyme linked immunosorbent assay (ELISA) based studies have been published for Australian and Japanese populations and the results indicate seroprevalences between 6 and 22 percent in healthy individuals, respectively. To investigate seroprevalence in Europe, we have developed a recombinant ELISA using a truncated MCV virion surface protein MC084 (V123-R230) expressed in E. coli. The ELISA was found to be sensitive and specific, with low inter- and intra-assay variability. Sera from 289 German adults and children aged 0-40 years (median age 21 years) were analysed for antibodies against MC084 by direct binding ELISA. The overall seropositivity rate was found to be 14.8%. The seropositivity rate was low in children below the age of one (4.5%), peaked in children aged 2-10 years (25%), and fell again in older populations (11-40 years; 12.5%). Ten out of 33 healthy UK individuals (30.3%; median age 27 years) had detectable MC084 antibodies. MCV seroconversion was more common in dermatological and autoimmune disorders, than in immunocompromised patients or in patients with multiple sclerosis. Overall MCV seroprevalence is 2.1 fold higher in females than in males in a UK serum collection. German seroprevalences determined in the MC084 ELISA (14.8%) are at least three times higher than incidence of MC in a comparable Swiss population (4.9%). While results are not strictly comparable, this is lower than Australian seroprevalence in a virion based ELISA (n = 357; 23%; 1999), but higher than the seroprevalence reported in a Japanese study using an N-terminal truncation of MC133 (n = 108, 6%; 2000. We report the first large scale serological survey of MC in Europe (n = 393) and the first MCV ELISA based on viral antigen expressed in E. coli.

Molecular epidemiology of molluscum contagiosum virus and analysis of the host-serum antibody response in Spanish HIV-negative patients

Molluscum contagiosum virus (MCV) lesions from Spanish human immunodeficiency virus (HIV)-negative patients were clinically examined and analyzed for virus detection and typing. In a study of 147 patients, 97 (66%) were children under 10 years, of whom 49% had atopic dermatitis. MCV lesions were morphologically indistinguishable among the different age groups, but atopic patients presented larger lesions compared with patients without the disorder. In adults, lesions were observed mainly on the genitals. MCVI was the predominant subtype. The deduced MCVI/MCVII ratio (146:1) was much higher than that found in other geographical areas. Protein preparations of the virus-induced lesions were immunoblotted with sera from 25 MCVI patients. The host-serum antibody response was weak and variable, although no significant differences were found between atopic and nonatopic patients. Three immunoreactive proteins of 74/80, 60, and 35 kDa were detected in almost all the analyzed sera. The 35 and 74/80-kDa proteins were virus specific, whereas the 60-kDa protein band was composed of a mix of human keratins. Immunoblotting of MCV lesions and vaccinia virus-infected cell extracts with either MCV patient serum or a rabbit antiserum against vaccinia virus showed no cross-reactivity of these two human poxviruses at the antigenic level.

Giant molluscum contagiosum in AIDS

A 31-year-old man, an intravenous drug user and in an advanced stage of acquired immune deficiency syndrome (AIDS), was admitted in our Department for the treatment of skin lesions that had been diagnosed as molluscum contagiosum (MC). The clinical examination revealed the presence of multiple nodular lesions, some of which were notably large and whose color resembled that of normal skin. These lesions were localized mainly to the face, and in particular on the forehead, glabellar, malar, beard, submandibular, and neck regions (Fig. 1). Smaller, crateriform lesions were detected on the hands and the upper limbs. The lymphocyte subsets ratio was 0.02, with a CD4+ T cell count of 13 cells per mm3 (1%) and a CD8+ T cell count of 624 per mm3 (48%). The patient also had leukopenia (1690 WBC per mm3), moderate macrocytic anemia, elevation of transaminases (SGOT 105 U/L, SGPT 114 U/L) and of immunoglobulins (IgG 2660 mg/dL), and a decrease of C3 (44.2 mg/dL) and C4 (16.6 mg/dL). Histologic examination revealed the presence of typical MC lesions. In addition to an important acanthosis, it was possible to detect pyriform lobules of perfectly delineated epidermal cells, radially separated by fibrous septa that merge towards the central crater. The characteristic MC eosinophil bodies were observed in infected cells (Fig. 2). The lesions were treated with cryosurgery by spray. Many courses of therapy were given with intervals of 2-3 weeks. Every session consisted of two cycles of rapid freezing followed by a slow thaw. Many lesions disappeared with this treatment, and others were reduced in size, but total destruction of all lesions was not achieved (Fig. 3).

Proinflammatory properties of molluscum bodies

Molluscum contagiosum, a condition characterized by benign viral tumours, occasionally becomes inflamed and regresses spontaneously, an event probably initiated by a host cell-mediated immune rejection against the lesion, but it inevitably involves the disruption of the epidermal tissue to expose the molluscum bodies to the tissue fluids of the dermis. It has been suggested that the molluscum bodies induce inflammation by a mechanism similar to that involved in ruptured epidermal cysts or in acne. Despite the occasional development of inflammation in molluscum contagiosum, the proinflammatory properties of molluscum bodies have never been studied in vitro. Thus, in the present study we sought to determine whether molluscum bodies exert a proinflammatory effect by inducing neutrophil chemotaxis. When exposed to fresh serum in vitro, water-insoluble components of molluscum bodies activated the alternative complement pathway to produce chemotactic C5a/C5a des Arg. We also found that an aqueous extract of molluscum bodies exerted potent chemotactic activity for neutrophils. Remarkably high amounts of the immunoreactive proinflammatory cytokines IL-8 and GRO alpha were present in the extract even when compared with psoriatic scale extracts. Gel filtration HPLC of the extract demonstrated the presence of neutrophil chemotactic activity over a wide range of molecular mass. These data suggest that disruption of the epidermal wall of molluscum bodies induces acute inflammatory changes by activation of the alternative complement pathway on exposure to the tissue fluids, and that the molluscum bodies themselves release proinflammatory cytokines and other neutrophil chemotactic factors on decomposition.