Neurogenic inflammation and colliquative lymphadenitis with persistent orthopox virus DNA detection in a human case of cowpox virus infection transmitted by a domestic cat

Pockenvirusinfektionen in der Dermatologie: Poxvirus infections in dermatology - the neglected, the notable, and the notorious

Die Familie Poxviridae umfasst derzeit 22 Gattungen, die Wirbeltiere infizieren können. Humanpathogene Pockenviren gehören den Gattungen Ortho‐, Para‐, Mollusci‐ und Yatapoxvirus an. Bis zur Eradikation der Variola vera im Jahr 1979 waren die Pocken, im Volksmund auch Blattern genannt, eine schwerwiegende Gesundheitsbedrohung für die Bevölkerung. Noch heute sind Dermatologen mit zahlreichen Pockenvirusinfektionen konfrontiert, wie den Bauernhofpocken, die als Zoonosen nach Tierkontakten in ländlichen Gebieten oder nach Massenversammlungen auftreten können. In den Tropen können Erkrankungen durch Tanapox‐ oder Vaccinia‐Viren zu den Differenzialdiagnosen gehören. Dellwarzen sind weltweit verbreitet und werden in bestimmten Fällen als sexuell übertragbare Pockenvirusinfektion angesehen. In jüngster Zeit hatten sich Mpox (Affenpocken) zu einer gesundheitlichen Notlage von internationaler Tragweite entwickelt, die eine rasche Identifizierung und angemessene Behandlung durch Dermatologen und Infektiologen erfordert. Fortschritte und neue Erkenntnisse über Epidemiologie, Diagnose, klinische Manifestationen und Komplikationen sowie Behandlung und Prävention von Pockenvirusinfektionen erfordern ein hohes Maß an Fachwissen und interdisziplinärer Zusammenarbeit in den Bereichen Virologie, Infektiologie und Dermatologie. Dieser CME‐Artikel bietet einen aktualisierten systematischen Überblick, um praktizierende Dermatologen bei der Identifizierung, Differenzialdiagnose und Behandlung klinisch relevanter Pockenvirusinfektionen zu unterstützen.

Poxvirus infections in dermatology - the neglected, the notable, and the notorious

The family Poxviridae currently comprises 22 genera that infect vertebrates. Of these, members of the Ortho-, Para-, Mollusci- and Yatapoxvirus genera have been associated with human diseases of high clinical relevance in dermatology. Historically, smallpox had been a notorious health threat until it was declared eradicated by the World Health Organization in 1979. Today, dermatologists are confronted with a variety of poxviral infections, such as farmyard pox, which occurs as a zoonotic infection after contact with animals. In the tropics, tanapox or vaccinia may be in the differential diagnosis as neglected tropical dermatoses. Molluscum contagiosum virus infection accounts for significant disease burden worldwide and is classified as a sexually transmitted infection in certain scenarios. Recently, mpox (monkeypox) has emerged as a public health emergency of international concern, requiring rapid recognition and appropriate management by dermatologists and infectious disease specialists. Advances and new insights into the epidemiology, diagnosis, clinical manifestations and complications, treatment, and prevention of poxviral infections require a high level of expertise and interdisciplinary skills from healthcare professionals linking virology, infectious diseases, and dermatology. This CME article provides a systematic overview and update to assist the practicing dermatologist in the identification, differential diagnosis, and management of poxviral infections.

A Belgian student with black eschars

BACKGROUND

Human cowpox virus infection is a rare zoonotic disease. Cowpox virus is a member of the Orthopoxvirus genus, like smallpox. Over the last years records of cowpox virus transmission from pet cats and pet rats to humans in Europe have increased. This observation may result from the loss of cross-immunity against orthopoxviruses after discontinuation of routine smallpox vaccination in the 1980s.

CASE PRESENTATION

We report the first case of a human cowpox infection in an unvaccinated Belgian citizen. This 19-year-old student presented with multiple necrotic skin lesions on the chin, the scalp and the pubic region, and with cervical lymphadenopathy and flu-like symptoms. The diagnosis of human cowpox was based on electron microscopic findings and PCR examination performed on a skin biopsy of the pubic lesion. Close contact with cats (her domestic cats or cats from a local shelter) was probably the source of transmission. Spreading of the lesions was likely the result of autoinoculation. After six months all lesions spontaneously healed with atrophic scars.

DISCUSSION

To enhance awareness of this rare viral zoonosis and to verify the suspected increase in incidence and symptom severity after cessation of smallpox vaccination, one could argue whether human cowpox should become a notifiable disease.

Vector-borne and other pathogens of potential relevance disseminated by relocated cats

Large populations of unowned cats constitute an animal welfare, ecological, societal and public health issue worldwide. Their relocation and homing are currently carried out in many parts of the world with the intention of relieving suffering and social problems, while contributing to ethical and humane population control in these cat populations. An understanding of an individual cat’s lifestyle and disease status by veterinary team professionals and those working with cat charities can help to prevent severe cat stress and the spread of feline pathogens, especially vector-borne pathogens, which can be overlooked in cats. In this article, we discuss the issue of relocation and homing of unowned cats from a global perspective. We also review zoonotic and non-zoonotic infectious agents of cats and give a list of practical recommendations for veterinary team professionals dealing with homing cats. Finally, we present a consensus statement consolidated at the 15th Symposium of the Companion Vector-Borne Diseases (CVBD) World Forum in 2020, ultimately to help veterinary team professionals understand the problem and the role they have in helping to prevent and manage vector-borne and other pathogens in relocated cats.

Graphical Abstract

New p35 (H3L) Epitope Involved in Vaccinia Virus Neutralization and Its Deimmunization

Vaccinia virus (VACV) is a promising oncolytic agent because it exhibits many characteristic features of an oncolytic virus. However, its effectiveness is limited by the strong antiviral immune response induced by this virus. One possible approach to overcome this limitation is to develop deimmunized recombinant VACV. It is known that VACV p35 is a major protein for B- and T-cell immune response. Despite the relevance of p35, its epitope structure remains insufficiently studied. To determine neutralizing epitopes, a panel of recombinant p35 variants was designed, expressed, and used for mice immunization. Plaque-reduction neutralization tests demonstrated that VACV was only neutralized by sera from mice that were immunized with variants containing both N- and C- terminal regions of p35. This result was confirmed by the depletion of anti-p35 mice sera with recombinant p35 variants. At least nine amino acid residues affecting the immunogenic profile of p35 were identified. Substitutions of seven residues led to disruption of B-cell epitopes, whereas substitutions of two residues resulted in the recognition of the mutant p35 solely by non-neutralizing antibodies.

What a Difference a Gene Makes: Identification of Virulence Factors of Cowpox Virus

Cowpox virus (CPXV) is a zoonotic orthopoxvirus (OPV) that causes spillover infections from its animal hosts to humans. In 2009, several human CPXV cases occurred through transmission from pet rats. An isolate from a diseased rat, RatPox09, exhibited significantly increased virulence in Wistar rats and caused high mortality compared to that caused by the mildly virulent laboratory strain Brighton Red (BR). The RatPox09 genome encodes four genes which are absent in the BR genome. We hypothesized that their gene products could be major factors influencing the high virulence of RatPox09. To address this hypothesis, we employed several BR-RatPox09 chimeric viruses. Using Red-mediated mutagenesis, we generated BR-based knock-in mutants with single or multiple insertions of the respective RatPox09 genes. High-throughput sequencing was used to verify the genomic integrity of all recombinant viruses, and transcriptomic analyses confirmed that the expression profiles of the genes that were adjacent to the modified ones were unaltered. While the in vitro growth kinetics were comparable to those of BR and RatPox09, we discovered that a knock-in BR mutant containing the four RatPox09-specific genes was as virulent as the RatPox09 isolate, causing death in over 75% of infected Wistar rats. Unexpectedly, the insertion of gCPXV0030 (g7tGP) alone into the BR genome resulted in significantly higher clinical scores and lower survival rates matching the rate for rats infected with RatPox09. The insertion of gCPXV0284, encoding the BTB (broad-complex, tramtrack, and bric-à-brac) domain protein D7L, also increased the virulence of BR, while the other two open reading frames failed to rescue virulence independently. In summary, our results confirmed our hypothesis that a relatively small set of four genes can contribute significantly to CPXV virulence in the natural rat animal model.IMPORTANCE With the cessation of vaccination against smallpox and its assumed cross-protectivity against other OPV infections, waning immunity could open up new niches for related poxviruses. Therefore, the identification of virulence mechanisms in CPXV is of general interest. Here, we aimed to identify virulence markers in an experimental rodent CPXV infection model using bacterial artificial chromosome (BAC)-based virus recombineering. We focused our work on the recent zoonotic CPXV isolate RatPox09, which is highly pathogenic in Wistar rats, unlike the avirulent BR reference strain. In several animal studies, we were able to identify a novel set of CPXV virulence genes. Two of the identified virulence genes, encoding a putative BTB/POZ protein (CPXVD7L) and a B22R-family protein (CPXV7tGP), respectively, have not yet been described to be involved in CPXV virulence. Our results also show that single genes can significantly affect virulence, thus facilitating adaptation to other hosts.

Skin lesions caused by Orthopoxvirus in children

Introduction

The global eradication of smallpox and abandonment of mandatory smallpox vaccination has led to an increased proportion of the population who are immunologically naïve to infections caused by Orthopoxviruses (OPV).

Aim

To present the different courses of OPV infection in children and to highlight the diagnostic difficulties in their differentiation from the other inflammatory processes.

Material and methods

We retrospectively evaluated the medical documentation of 5 children with OPV infection. Clinical diagnosis of OPV infection was based on evaluation of animal contact and skin symptoms, characterised by either a single ulcer or disseminated lesions. In all five cases, blood samples and skin swabs were collected from the lesion(s) to identify specific OPV DNA fragments (Vgf, b9R and D11L genes) using PCR.

Results

Two children presented with high fever, a single ulcer on the skin and local lymphadenopathy. The three other patients were in good general health and their skin lesions presented as a disseminated vesicular rash. Using the Vgf gene as the target for PCR, OPV infection was confirmed in material collected from skin lesions of all children and in blood samples of 4 children. The B9R and d11L genes tested positive in the skin material of 2 children and blood samples of 2 children. All analysed patients presented a history of ineffective antibiotic therapy.

Conclusions

In the case of unclear necrotising skin lesions in children, the primary diagnosis always includes bacterial dermatitis. However, if the patient has come into contact with animals, diagnosis of OPV infection should also be considered.

Immunogenicity of recombinant fragment of orthopoxvirus p35 protein in mice

Despite the elimination of smallpox, orthopoxviruses continue to be a source of biological danger for humans, as cowpox and monkey pox viruses circulate in nature and the last virus can cause both sporadic cases of human diseases and outbreaks of smallpox-like infection. In addition, periodic vaccination is necessary for representatives of some professions (scientists studying pathogenic orthopoxviruses, medical personnel, etc.). Vaccination against smallpox virus with live vaccinia virus, which was widely used during the elimination of smallpox, induces the formation of long-term immunity in vaccinated people. However, providing a high level of protection, the vaccination is often accompanied by serious post-vaccination complications, the probability of which is particularly great for individuals with compromised immunity. In this regard, the development of preparations for the prevention and treatment of infections caused by orthopoxviruses remains important today. The aim of this study was to assess the immunogenicity in the mouse model of recombinant protein р35Δ12, designed previously on the base of the cowpox virus protein p35. It was previously shown that the protein р35Δ12 was recognized by fully human neutralizing anti-orthopoxviral antibody with high affinity. In this work, recombinant protein р35Δ12 produced in E. coli cells XL1-blue and purified by chromatography was used for two-time immunization of mice. Two weeks after the second immunization, blood samples were taken from mice and serum antibodies were analyzed. It was shown by ELISA and Western-blot analysis that immunized mice sera contained IgG antibodies specific to recombinant protein р35Δ12. Confocal microscopy showed that antibodies induced by the р35Δ12 protein were able to recognize Vero E6 cells infected with the LIVP-GFP vaccinia virus. In addition, the antibodies in the serum of immunized mice were able to neutralize the infectivity of the vaccinia virus LIVP-GFP in the plaque reduction neutralization test in vitro. These experiments have demonstrated promising properties of the р35Δ12 protein if it were used as a component of vaccine for prophylaxis of orthopoxvirus infections.

[What's new in clinical dermatology?]

Significant advances have been performed in cutaneous adverse reactions leading to primary prevention strategy and implication of new signaling pathways. Histological features of DRESS and methotrexate toxicity are detailed. New emerging infectious agents are reported including Zika Virus, an arbovirus which can be confused with dengue or chikungunya, a new cowpox virus transmitted by domestic cat leading to lymphadenitis, Spirurina type X larva transmitted in Japan by eating raw squid or fish. Malignancies in pemphigus and pemphigoid are emphasized. Expert recommandations are developped on definitions, diagnosis and disease activity of mucous membrane pemphigoid, bubllous pemphigoid and pemphigus. Psoriasis and cardiometabolic association are discussed. This risk association appears higher in hidradenitis suppurativa, which seems more frequent in patients of African ancestry. IgG4-related disease is an immune mediated entity characterized by fibroinflammatory lesions often misdiagnosed. Pruritus, heat sensations, numbness could be recognized as a small-fiber neuropathy symptoms. Burden impact in common dermatosis is demonstrated and should be integrated in our daily practice.

Histopathological and Immunohistochemical Studies of Cowpox Virus Replication in a Three-Dimensional Skin Model

Human cowpox virus (CPXV) infections are rare, but can result in severe and sometimes fatal outcomes. The majority of recent cases were traced back to contacts with infected domestic cats or pet rats. The aim of the present study was to evaluate a three-dimensional (3D) skin model as a possible replacement for animal experiments. We monitored CPXV lesion formation, viral gene expression and cell cycle patterns after infection of 3D skin cultures with two CPXV strains of different pathogenic potential: a recent pet rat isolate (RatPox09) and the reference Brighton red strain. Infected 3D skin cultures exhibited histological alterations that were similar to those of mammal skin infections, but there were no differences in gene expression patterns and tissue damage between the two CPXV strains in the model system. In conclusion, 3D skin cultures reflect the development of pox lesions in the skin very well, but seem not to allow differentiation between more or less virulent virus strains, a distinction that is made possible by experimental infection in suitable animal models.