Cowpox virus in a 12-year-old boy: rapid identification by an orthopoxvirus-specific polymerase chain reaction

Novel Orthopoxvirus and Lethal Disease in Cat, Italy

We report detection and full-genome characterization of a novel orthopoxvirus (OPXV) responsible for a fatal infection in a cat. The virus induced skin lesions histologically characterized by leukocyte infiltration and eosinophilic cytoplasmic inclusions. Different PCR approaches were unable to assign the virus to a defined OPXV species. Large amounts of typical brick-shaped virions, morphologically related to OPXV, were observed by electron microscopy. This OPXV strain (Italy_09/17) was isolated on cell cultures and embryonated eggs. Phylogenetic analysis of 9 concatenated genes showed that this virus was distantly related to cowpox virus, more closely related to to ectromelia virus, and belonged to the same cluster of an OPXV recently isolated from captive macaques in Italy. Extensive epidemiologic surveillance in cats and rodents will assess whether cats are incidental hosts and rodents are the main reservoir of the virus. The zoonotic potential of this novel virus also deserves further investigation.

Pulmonary cowpox in cats: five cases

CASE SERIES SUMMARY

This case series documents five cases of pneumonia (with pleural effusion in three cases) caused by cowpox virus (CPxV) in domestic cats. Predisposition to pneumonia may have resulted from mixed infections in two cases (feline herpesvirus and Bordetella bronchiseptica in one cat, and Mycoplasma species in the other).

RELEVANCE AND NOVEL INFORMATION

As well as diagnostic confirmation by previously described methods of virus isolation from skin lesions, and demonstration of pox virions in skin samples using electron microscopy and inclusion bodies in histological preparations, this is the first report of diagnosis by virus isolation from bronchoalveolar lavage fluid or pleural fluid, and demonstration of inclusion bodies in cytological preparations. This is also the first series to report treatment with interferon omega (IFN-ω). Two cats survived, both of which had been treated with IFN-ω. As CPxV represents a serious zoonotic risk it is an important differential diagnosis of pneumonia in cats.

Humans and cattle: a review of bovine zoonoses

Infectious disease prevention and control has been among the top public health objectives during the last century. However, controlling disease due to pathogens that move between animals and humans has been challenging. Such zoonotic pathogens have been responsible for the majority of new human disease threats and a number of recent international epidemics. Currently, our surveillance systems often lack the ability to monitor the human-animal interface for emergent pathogens. Identifying and ultimately addressing emergent cross-species infections will require a "One Health" approach in which resources from public veterinary, environmental, and human health function as part of an integrative system. Here we review the epidemiology of bovine zoonoses from a public health perspective.

Development of real-time PCR assay for specific detection of cowpox virus

Background

The number of recorded human cowpox cases are recently increasing. The symptoms caused by cowpox virus (CPXV) in a number of human cases are close to the symptoms characteristic of the orthopoxviral human infections caused by monkeypox or smallpox (variola) viruses. Any rapid and reliable real-time PCR method for distinguishing cowpox from smallpox and monkeypox is yet absent.

Objectives

The aim of this study was to develop a quick and reliable real-time TaqMan PCR assay for specific detection of cowpox virus and to determine the sensitivity and specificity of this method.

Study design

Based on aligned nucleotide sequences of orthopoxviruses, we found a virus-specific region in the CPXV genome and selected the oligonucleotide primers and hybridization probe within this region. The specificity of the developed method was tested using a panel of various orthopoxvirus (OPV) DNAs. The sensitivity was determined using the recombinant plasmid carrying a fragment of CPXV DNA and genomic DNA of the CPXV strain GRI-90.

Results

The analytical specificity of this method was determined using DNAs of 17 strains of four OPV species pathogenic for humans and amounted to 100%. The method allows 6 copies of plasmid DNA and 20 copies of CPXV DNA in the reaction mixture to be detected.

Conclusion

A quick and reliable TaqMan PCR assay providing for a highly sensitive and specific detection of CPXV DNA was developed.

Cytokine determinants of viral tropism

The specificity of a given virus for a cell type, tissue or species - collectively known as viral tropism - is an important factor in determining the outcome of viral infection in any particular host. Owing to the increased prevalence of zoonotic infections and the threat of emerging and re-emerging pathogens, gaining a better understanding of the factors that determine viral tropism has become particularly important. In this Review, we summarize our current understanding of the central role of antiviral and pro-inflammatory cytokines, particularly the interferons and tumour necrosis factor, in dictating viral tropism and how these cytokine pathways can be exploited therapeutically for cancer treatment and to better counter future threats from emerging zoonotic pathogens.

Cowpox virus expresses a novel ankyrin repeat NF-kappaB inhibitor that controls inflammatory cell influx into virus-infected tissues and is critical for virus pathogenesis

Many pathogenic orthopoxviruses like variola virus, monkeypox virus, and cowpox virus (CPXV), but not vaccinia virus, encode a unique family of ankyrin (ANK) repeat-containing proteins that interact directly with NF-kappaB1/p105 and inhibit the NF-kappaB signaling pathway. Here, we present the in vitro and in vivo characterization of the targeted gene knockout of this novel NF-kappaB inhibitor in CPXV. Our results demonstrate that the vCpx-006KO uniquely induces a variety of NF-kappaB-controlled proinflammatory cytokines from infected myeloid cells, accompanied by a rapid phosphorylation of the IkappaB kinase complex and subsequent degradation of the NF-kappaB cellular inhibitors IkappaBalpha and NF-kappaB1/p105. Moreover, the vCpx-006KO virus was attenuated for virulence in mice and induced a significantly elevated cellular inflammatory process at tissue sites of virus replication in the lung. These results indicate that members of this ANK repeat family are utilized specifically by pathogenic orthopoxviruses to repress the NF-kappaB signaling pathway at tissue sites of virus replication in situ.

[Human infection by the cowpox virus in the microregion of Itajubá, state of Minas Gerais: case report]

The authors report three human cases of cowpox infection, among farm workers who were manually milking infected cows, in the microregion of Itajubá, Minas Gerais. The diagnostic techniques used were: isolation of samples similar to the vaccinia virus, from skin lesion secretions; polymerase chain reaction; electronic microscopy; and antibodies for Orthopoxvirus in the patients' blood.

Fast and reliable diagnostic methods for the detection of human poxvirus infections

Although the most prominent poxvirus, Variola virus, was successfully eradicated in the last century, several other poxviruses cause zoonotic infections that, in the early stages, resemble Variola virus infections with varying pathogenicity in humans. Over recent decades, numerous diagnostic methods for the detection of poxviruses have been established. As a result of technical progress and the advancement in molecular techniques, only a small selection of these methods meet the demands of being rapid and reliable. This review briefly introduces human poxviruses, summarizes the methods available, discusses their pros and cons and provides recommendations for a ‘fast and reliable diagnostic approach.

Orthopoxvirus infection transmitted by a domestic cat

The variola virus was declared eradicated by the World Health Organization in 1980 but human infections by cowpox virus, another member of the genus Orthopoxvirus, are still observed, mainly in European countries. We report a woman who presented with two umbilicated vesicles surrounded by an indurated erythematous edema within cat scratch injuries on her thigh. The diagnosis of an Orthopoxvirus infection was based on the visualization of characteristic virus particles by electron microscopy and the detection of the A27L gene (14-kd fusion protein gene) of the genus Orthopoxvirus by polymerase chain reaction from a lesional skin biopsy specimen. Differential diagnoses of cat scratch disease, pustula maligna, and bullous impetigo were excluded by microbiologic investigation of the biopsy specimen. Both lesions scarred after 6 weeks of a continuous local antiseptic treatment.

Viral zoonoses in Europe

A number of new virus infections have emerged or re-emerged during the past 15 years. Some viruses are spreading to new areas along with climate and environmental changes. The majority of these infections are transmitted from animals to humans, and thus called zoonoses. Zoonotic viruses are, as compared to human-only viruses, much more difficult to eradicate. Infections by several of these viruses may lead to high mortality and also attract attention because they are potential bio-weapons. This review will focus on zoonotic virus infections occurring in Europe.

Development and Experience with an Algorithm to Evaluate Suspected Smallpox Cases in the United States, 2002-2004

Concerns that smallpox, an eradicated disease, might reappear because of a bioterror attack and limited experience with smallpox diagnosis in the United States prompted us to design a clinical algorithm. We used clinical features of classic smallpox to classify persons presenting with suspected smallpox rashes into 3 categories: those with high, those with moderate, and those with low risk of having smallpox. The classification guides subsequent diagnostic strategies, limiting smallpox laboratory testing to high-risk persons to minimize the number of false-positive test results. From January 2002 through June 2004, the Centers for Disease Control and Prevention (CDC) received 43 consultations regarding suspected smallpox cases. No patient was at high risk for having smallpox. One patient was tested for the presence of variola virus. Varicella was the diagnosis for 23 cases (53%). The algorithm worked well to guide clinical and public health responses to suspected smallpox cases. The poster is available from CDC, and an interactive version and laboratory protocol are available at http://www.bt.cdc.gov/agent/smallpox/diagnosis/riskalgorithm/index.asp. We recommend use of the algorithm in the United States and elsewhere.

Zoonotic poxvirus infections in humans

PURPOSE OF REVIEW

The 2003 USA monkeypox epidemic caused by imported African rodents, newly emergent poxvirus zoonoses in Brazil and the possible use of variola virus for biological warfare has led to renewed interest in poxviruses and anti-poxviral therapies. Increasing foreign travel and importation of exotic animal species increases the likelihood of poxvirus infections occurring outside their usual geographical range and diagnostic delay has important implications. The present review provides an overview of these rare zoonoses.

RECENT FINDINGS

Three genera of Poxviridae are known to cause human zoonoses: orthopoxviruses, parapoxviruses and yatapoxvirus. Most cases are occupational, sporadic and have few cutaneous lesions with low morbidity. The exception is monkeypox, similar to smallpox, with significant morbidity and childhood mortality. Molecular characterization using polymerase chain reaction (PCR) amplification and other methods provides accurate phylogenetic identification and suggests that a cowpox-like virus is the probable ancestor of variola and other zoonotic poxviruses. DNA genomic sequencing of the Brazilian Cantagalo and Araçatuba viruses shows a close relationship to vaccinia virus. Poxviruses have potential in cancer immunotherapy and their ability to evade host-cell immune responses may provide a basis for new antipoxvirus therapies. Other agents, particularly nucleoside phosphonates such as cidofovir, show therapeutic action against poxviruses.

SUMMARY

Human zoonotic poxvirus infections are rare but increasingly encountered outside their usual geographical range. The 2003 USA monkeypox outbreak emphasizes the importance of early accurate diagnosis, particularly because increasing numbers of immunosuppressed individuals increases the potential for severe or fatal infections. PCR methodology enables accurate phylogenetic typing and has identified new diseases, but rapid, reliable methods must be made available for clinicians. More research into therapeutic agents for the prevention and treatment of poxvirus infections is required.

Cowpox with severe generalized eruption, Finland

Cowpox with a severe, generalized eruption was diagnosed in an atopic 4-year-old girl by electron microscopy, virus isolation, polymerase chain reaction, and immunoglobulin (Ig) M and low-avidity IgG antibodies. The hemagglutinin gene of the isolate clustered with a Russian cowpox virus strain, and more distantly, with other cowpox and vaccinia virus strains. The patient’s dog had orthopoxvirus-specific antibodies, indicating a possible transmission route.

Feline orthopoxvirus infection transmitted from cat to human

We report the case of a 56-year-old female patient who presented with an inflamed, ulcerated lesion on the left side of her neck after contact (scratch) with a cat living in the patient's house. Satellite lesions developed despite local treatment and parenteral clindamycin. Histopatholgic examination and the Tzanck test showed evidence of a viral infection. Subsequent transmission electron microscopy of scrap tissue and material from a fresh pustule exhibited multiple typical poxvirus particles, predominantly in remnants of scaled-off layers of degenerated keratinocytes, and virus particles in intermingled phagocytes, leading to the diagnosis of feline Orthopoxvirus (cowpox virus) infection. These results were verified by polymerase chain reaction and sequencing. Concern has been raised as to whether discontinuation of smallpox vaccine would cause an increase in Orthopoxvirus infection, but this has not yet shown to be the case.