Cowpox Virus Infection Research Articles

Poxvirus infection in a cat with presumptive human transmission

The present report describes a case of generalized cowpox virus infection with necrotizing facial dermatitis in a cat and a likely transmission to an animal keeper. The viral aetiology was confirmed by histopathology, immunohistochemistry, PCR, virus isolation, DNA sequencing and electron microscopy. Histopathological examination of the cat's skin revealed a severe, necrotizing dermatitis with ballooning degeneration and hyperplasia of epithelial cells with pathognomonic cytoplasmic eosinophilic inclusion bodies. Additionally, at post-mortem examination, a systemic poxvirus infection was detected affecting pancreas, thymus, lymph node, liver and lung. The human patient's skin biopsy revealed an ulcerative dermatitis with epidermal hyperplasia and ballooning degeneration. Serological investigation displayed a high orthopoxvirus-specific antibody titre in the human patient. Environmental factors increase the natural reservoir host population for cowpox viruses, such as voles, which results in a higher risk of infection for cats and subsequently for humans. Due to this zoonotic potential, a cowpox virus infection must be considered as an aetiological differential in cases of necrotizing dermatitis in cats.

Lésions cutanées nécrotiques liées au Cowpox virus inoculé par des rats de compagnie

We report 2 observations in young girls who, after exposure to domestic rats from the same pet shop, presented with inflammatory and necrotic skin wounds in the neck and face. Since lesions did not improve with antibiotic therapy, surgical excision of necrosis healed the wounds, with a 2nd intervention necessary in 1 patient. All bacteriological investigations appeared to be negative; finally, electron microscopy of excised subepidermal tissue and PCR characterization provided the diagnosis of cowpox virus (CPXV) infection. CPXV is part of the Orthopox virus genus, like variola virus, and is generally transmitted to humans by infected cats or rodents. CPXV infection should be kept in mind when macular, vesicular, or necrotic cutaneous wounds do not improve with antibiotics.

Treatment of Vaccinia and Cowpox Virus Infections in Mice with CMX001 and ST-246

Although a large number of compounds have been identified with antiviral activity against orthopoxviruses in tissue culture systems, it is highly preferred that these compounds have activity in vivo before they can be seriously considered for further development. One of the most commonly used animal models for the confirmation of this activity has been the use of mice infected with either vaccinia or cowpox viruses. These model systems have the advantage that they are relatively inexpensive, readily available and do not require any special containment facilities; therefore, relatively large numbers of compounds can be evaluated in vivo for their activity. The two antiviral agents that have progressed from preclinical studies to human safety trials for the treatment of orthopoxvirus infections are the cidofovir analog, CMX001, and an inhibitor of extracellular virus formation, ST-246. These compounds are the ones most likely to be used in the event of a bioterror attack. The purpose of this communication is to review the advantages and disadvantages of using mice infected with vaccinia and cowpox virus as surrogate models for human orthopoxvirus infections and to summarize the activity of CMX001 and ST-246 in these model infections.

Cannabinoids lead to enhanced virulence of the smallpox vaccine (vaccinia) virus

Indian hemp is used since thousands of years as herbal drug. We found that a single dose of cannabis resin was equally active as Δ9-tetrahydrocannabinol (THC) enhancing severity and duration of symptoms in vaccinia virus infected mice. Cowpox virus did not cause symptomatic disease, but some reduction of specific antibody production was observed in drug treated animals. In vitro cannabis was superior to THC alone at inhibiting mitogen stimulated proliferation of human and mouse spleen cells and peripheral blood mononuclear cells. Also resin sub-fractions other than THC, cannabidiol and cannabinol, recovered also from cigarette smoke, were found inhibitory, suggesting additional involvement of constituents other than psychoactive THC. The immunoregulatory effects must be differentiated from apoptotic effects on spleen cells and lymphocytic mouse cell lines, which were observed with resin and THC but not with cannabidiol or cannabinol. A significant contribution of cytotoxic effects seems unlikely as drug treated lymphocytes were still capable of producing cytokines after T-cell receptor-specific stimulation. Considering a recent case of unusually severe cowpox virus infection in a young drug taker these data confirm a risk of “soft drugs” for acquiring poxvirus infection or enhancing side effects of the smallpox vaccine and perhaps also other live vaccines.

Localized cowpox infection in a 5‐month‐old Rottweiler

Cowpox virus (CPXV) infections are a sporadic cause of localized or disseminated skin disease in domestic animals and humans in Europe. Rodents are considered the primary reservoir host for CPXV. Cats can become infected by close contact with rodents and are the most important source of human infections. Recently, public awareness has also been drawn to CPXV infections by an outbreak of rat to human infections in central Europe. In dogs, CPXV infections are rare. Here we report a case of a 5-month-old Rottweiler with a focal nodule on the muzzle. The lesion was fully excised, and recovery was uneventful. The preliminary diagnosis of a CPXV infection was established by the characteristic inclusion bodies on histopathological examination. The diagnosis was confirmed by electron microscopy and polymerase chain reaction (PCR). Sequencing of the PCR product led to a 231 bp sequence of the orthopoxvirus HA gene that was identical to a CPXV strain previously isolated from a cat. This is the third documented case of a canine CPXV infection.

Human cowpox virus infection acquired from a circus elephant in Germany

A 40-year-old Asian circus elephant developed mouth and trunk ulcers. Three weeks later, her 19-year-old animal warden noticed a vesicle on his forearm, evolving into a scab. Identical cowpox strains were isolated from lesions of the elephant and the warden. Cowpox virus could no longer be isolated after the scab disappeared, but PCR still revealed orthopox DNA. Healing was complete seven weeks later, leaving a 1 cm scar.

Lack of Efficacy of Aurintricarboxylic Acid and Ethacrynic Acid against Vaccinia Virus Respiratory Infections in Mice

Aurintricarboxylic acid (ATA) and ethacrynic acid (ECA) have been reported to exhibit antiviral activity against vaccinia virus infections in cell culture by inhibiting early and late gene transcription, respectively. The purpose of this work was to determine if these inhibitors would effectively treat vaccinia virus infections in mice, which has not previously been studied. ECA was investigated by cell culture plaque reduction assay for the inhibition of cowpox and vaccinia virus infections to clarify issues regarding its potency and selectivity. Mice infected intranasally with vaccinia virus were treated by intraperitoneal route twice daily for 5 days with ATA (10 and 30 mg/kg/day) and ECA (15 and 30 mg/kg/day) or once daily for 2 days with cidofovir (100 mg/kg/day). ECA caused 50% inhibition of virus plaque formation at 20-79 muM in four cultured cell lines, with 50% cytotoxicity at 84-173 muM, giving low (1.3-4.2) selectivity index values. Preliminary toxicity tests in uninfected mice indicated that ATA and ECA were both overtly toxic at 100 mg/kg/day. No protection from mortality was afforded by treatment of vaccinia virus infections with ATA or ECA, but 100% survival was achieved in the cidofovir group. ATA- and ECA-treated mice died significantly sooner than placebo-treated animals, indicating that these compounds exacerbated the infection. Both ATA and ECA lack antiviral potency and selectivity in cell culture. The compounds were ineffective in treating mice at intraperitoneal doses of <or=30 mg/kg/day. These compounds do not appear to have potential for the treatment of poxvirus infections in vivo.

Fatal Cowpox Virus Infection in Captive Banded Mongooses (Mungos mungo)

Cowpox virus infections have been described in various domestic and exotic animal species. This report is the first on an outbreak of fatal generalized cowpox virus infection among captive banded mongooses (Mungos mungo, suborder Feliformia). All animals of a colony of 8 mongooses showed a fulminant course of disease. The whole population died (n=7) or was euthanized (n=1) within 11 days. Postmortem examinations were performed on 4 animals. All animals showed extensive necrotizing inflammation of retropharyngeal lymph nodes, typical poxviral skin lesions, and multiple necrotic foci in liver and spleen. Three animals exhibited an ulcerating stomatitis. Pulmonary lesions, a common feature of fatal cowpox virus infections in other feliform species, were not obvious. Histopathologically, characteristic cytoplasmic inclusion bodies were detected in all affected organs but the spleen. Based on transmission electron microscopy and cell culture, Orthopoxvirus was identified as the etiology. The virus was further characterized by polymerase chain reaction and sequence analysis, identifying it as cowpox virus. A survey in the habitat suggests wild brown rats (Rattus norvegicus) as the most likely source of infection.

Human cowpox in a veterinary student

A 19-year-old previously well female veterinary student with regular contact with diverse species of animals presented with an initially small red plaque on her left cheek. During the next 3 weeks the lesion developed into an ulcerated nodule 4 cm in size with a brownish eschar on top, a satellite papule, and marked infl ammation of the surrounding skin (fi gure). The patient had malaise and a painful pronounced cervical lymphadenopathy. Laboratory investigations were unremarkable except for a transient elevation of C-reactive protein (820 mg/L), neutropenia (38%), and eosinophilia (11%). During 2 weeks of intravenous treatment with piperacillin and tazobactam combined fi rst with clindamycin then doxycycline, the nodule demarcated but persisted, and a complete necrectomy was done. The resulting large tissue defect was reconstructed in a separate operation. Serology for Francisella tularensis, Bartonella henselae, Yersinia enterocolitica O3 and O9 antigens, Leishmania spp, Rickettsia conorii, and R mooseri were all negative. Bacterial cultures were negative, including Bacillus anthracis and Mycobacterium tuberculosis. Histopathology showed full-thickness necrosis of the skin. Brick-shaped orthopoxvirus particles were evident on electron microscopy (fi gure) and quantitative real-time PCR of the haemagglutinin gene of the cowpox virus was positive, leading to the diagnosis of human cowpox. Sequence analysis by direct DNA sequencing identifi ed the isolate AT_Styria/84/09 (Genbank accession number FJ7692784) that is closely related to a cowpox virus isolated from domestic cats in Austria. Cowpox virus infections represent a very rare zoonosis in human beings. However, increasing numbers of cases in young people have been documented recently, presumably because of a lack of cross-reactive immunity after the end of routine smallpox vaccination in the late 1970s. The disease remains localised and is self-limiting in patients that are immunocompetent, although dissemination and fatal courses have been reported. After an incubation period of 7–12 days after direct skin contact with cats, which are the main source of infections in people, patients develop a necrotising nodule with consecutive scar formation, accompanied by malaise, raised temperature, and long-lasting, pronounced, and painful regional lymphadenopathy. Diagnosis is made on the basis of electron microscopy and PCR of the lesion. Although no approved specifi c antiviral treatment exists against infections with the cowpox virus, cidofovir can be given in complicated cases. Plastic surgery might be necessary to avoid substantial aesthetic consequences.

Genetic diversity of feline cowpox virus, Germany 2000–2008

Recent cowpox virus (CPXV) infections of humans in Europe transmitted from cats and pet rats have risen public awareness of this rare zoonosis. Based on serosurveys wild rodents are regarded as primary reservoir hosts. Cats can become infected while hunting and could therefore serve as a sentinel for CPXV strains circulating in wild rodents. In a retrospective study we analysed 73 formalin-fixed paraffin-embedded skin samples from cats with a histologically proven CPXV infection. Specimens had been collected in different parts of Germany during 2000–2008. Following DNA extraction part of the hemagglutinin gene was amplified and sequenced from 72 samples. A phylogenetic analysis was inferred resulting in a total of 21 different CPXV genetic variants. The geographic distribution was imposed on a map.

Cowpox Virus Infection in Pet Rat Owners—Not Always Immediately Recognized: Human to Human Transmission of Poxviruses Have Been Observed Previously

I read the article by Becker et al, on cowpox infections in owners of pet rats (1), with great interest as I was involved with cowpox through my work from 1970 to 1974. The authors write that human to human transmission has not been observed so far. However, according to my own experiences, human to human transmission should be classed at least as possible. Thirty seven years ago I worked in the state vaccination institute in Dusseldorf. A 35 year old woman had received a visit from an 11 month old child. She had held the child in her arms and petted and stroked it. She was not aware that the child had been vaccinated against smallpox 4 weeks previously. Three days later, the woman developed pea sized efflorescences on her left cheek and her right and left upper arms. These remained in place for 6 days; she consulted a doctor who suspected smallpox and referred her to the university dermatology hospital in M. Specimens were taken and sent to the vaccination institute in Dusseldorf for investigation. Smallpox viruses were found on electron microscopy in two specimens—a clear case of human to human transmission. The then director of the state vaccination institute, Dr Richter, and I reported extensively about the case in the journal Offentliches Gesundheits-Wesen [public health] (2).

Cowpox Virus Infection in Pet Rat Owners—Not Always Immediately Recognized: In reply

Cowpox Virus Infection in Pet Rat Owners—Not Always Immediately Recognized: In reply

Cowpox Virus Infection in Pet Rat Owners—Not Always Immediately Recognized: Human to Human Transmission Is Possible in Orthopoxviruses

I wish to congratulate the authors for their clear and well structured case reports and their detailed photographs. This publication will enable more rapid diagnosis of further cases (1). In the meantime, Campe et al have published an article in Emerging Infectious Diseases about the transmission of cowpox from rats to humans in the Munich area (2). Human to human transmission has been described for orthopoxviruses. In 2007, Zafar et al reported nosocomial infections with buffalopox viruses in burns wards in Karachi, Pakistan; a class of virus that also belongs to the genus orthopoxvirus (3). Zafar et al observed buffalopox for 5 months in 2004–5 in 19 patients from 5 burn units. A health care worker developed an infection on a finger. In all cases, the causative strain was confirmed and typed with support from the Special Pathogens Unit at the National Institute for Communicable Diseases (NICD), Sandringham, South Africa, and the Health Protection Agency (HPA)’s Centre for Emergency Preparedness and Response in Porton Down, Salisbury, United Kingdom. The authors recommend that patients should be warned about the risk of smear (contact) infections, as it happened at least in patient No 4 (lesions on abdominal skin and eye). Identification of cowpoxviruses in the biopsy specimen from a pulmonary focus proves that pneumonia in patient 6 was caused by the virus.

Cowpox Virus Outbreak in Banded Mongooses (Mungos mungo) and Jaguarundis (Herpailurus yagouaroundi) with a Time-Delayed Infection to Humans

BackgroundOften described as an extremely rare zoonosis, cowpox virus (CPXV) infections are on the increase in Germany. CPXV is rodent-borne with a broad host range and contains the largest and most complete genome of all poxviruses, including parts with high homology to variola virus (smallpox). So far, most CPXV cases have occurred individually in unvaccinated animals and humans and were caused by genetically distinguishable virus strains.Methodology/Principal FindingsGeneralized CPXV infections in banded mongooses (Mungos mungo) and jaguarundis (Herpailurus yagouaroundi) at a Zoological Garden were observed with a prevalence of the affected animal group of 100% and a mortality of 30%. A subsequent serological investigation of other exotic animal species provided evidence of subclinical cases before the onset of the outbreak. Moreover, a time-delayed human cowpox virus infection caused by the identical virus strain occurred in a different geographical area indicating that handling/feeding food rats might be the common source of infection.Conclusions/SignificanceReports on the increased zoonotic transmission of orthopoxviruses have renewed interest in understanding interactions between these viruses and their hosts. The list of animals known to be susceptible to CPXV is still growing. Thus, the likely existence of unknown CPXV hosts and their distribution may present a risk for other exotic animals but also for the general public, as was shown in this outbreak. Animal breeders and suppliers of food rats represent potential multipliers and distributors of CPXV, in the context of increasingly pan-European trading. Taking the cessation of vaccination against smallpox into account, this situation contributes to the increased incidence of CPXV infections in man, particularly in younger age groups, with more complicated courses of clinical infections.

Survival of a cat with pneumonia due to cowpox virus and feline herpesvirus infection

Cowpox virus infection in cats is rare and usually leads to cutaneous lesions alone. Pulmonary infection and pneumonia have been documented occasionally but all such cases described to date have been fatal. Although usually affecting the upper respiratory tract, feline herpesvirus can also induce pneumonia. The present report describes the case of a cat that recovered from a pneumonia in which both poxvirus and feline herpesvirus were demonstrated.

Patterns of Orthopox Virus Wild Rodent Hosts in South Germany

Although cowpox virus (CPXV) infections in a variety of dead-end hosts have been investigated in Germany for more than 50 years, data on species and geographical distribution of CPXV in reservoir hosts are sparse. Here we present the first comprehensive study of 825 rodents that have been collected in Bavaria, Southern Germany. In summary, six different rodent species (Apodemus flavicollis, Myodes glareolus, Microtus arvalis, Apodemus sylvaticus, Microtus agrestis, and Arvicola amphibius) were trapped at three main trapping sites and investigated using a serum neutralization test (SNT). Prevalence of orthopox virus (OPV)-neutralizing antibodies was (with exception of one trapping site) highest in bank voles, ranging from 24.5% to 42.4%; often with SNT titers > or =96. Two up to 25% of yellow-necked mice were OPV sero-positive, but wood mice only at one site with 5.5%. Up to 7.7% of common voles were found to be OPV seroreactive, while M. agrestis and A. amphibius only sporadically showed seroreactivity. Further analyses of a subset of 450 bank voles and yellow-necked mice trapped at one site over a 18-month period revealed that male yellow-necked mice and female gravid yellow-necked mice had significantly more OPV-neutralizing antibodies. Mean body weight and OPV-seroreactivity were significantly negatively associated in male A. flavicollis. This was not due to shorter body length or smaller body mass index, but previously OPV-infected male A. flavicollis had dramatically reduced mean kidney weights. Seroreactivity in female bank voles was positively related to lung weights. We also found that both male yellow-necked mice and male bank voles with positive SNT titers had higher infestation rates with ectoparasites. We here show for the first time that A. flavicollis beside M. glareolus is a hypothetic host for CPXV, and that there are big geographical and spatial variations concerning the seroprevalence in rodent populations in South Germany.

Host–pathogen time series data in wildlife support a transmission function between density and frequency dependence

A key aim in epidemiology is to understand how pathogens spread within their host populations. Central to this is an elucidation of a pathogen's transmission dynamics. Mathematical models have generally assumed that either contact rate between hosts is linearly related to host density (density-dependent) or that contact rate is independent of density (frequency-dependent), but attempts to confirm either these or alternative transmission functions have been rare. Here, we fit infection equations to 6 years of data on cowpox virus infection (a zoonotic pathogen) for 4 natural populations to investigate which of these transmission functions is best supported by the data. We utilize a simple reformulation of the traditional transmission equations that greatly aids the estimation of the relationship between density and host contact rate. Our results provide support for an infection rate that is a saturating function of host density. Moreover, we find strong support for seasonality in both the transmission coefficient and the relationship between host contact rate and host density, probably reflecting seasonal variations in social behavior and/or host susceptibility to infection. We find, too, that the identification of an appropriate loss term is a key component in inferring the transmission mechanism. Our study illustrates how time series data of the host-pathogen dynamics, especially of the number of susceptible individuals, can greatly facilitate the fitting of mechanistic disease models.

Activation of the PI3K/Akt Pathway Early during Vaccinia and Cowpox Virus Infections Is Required for both Host Survival and Viral Replication

Viral manipulation of the transduction pathways associated with key cellular functions such as actin remodeling, microtubule stabilization, and survival may favor a productive viral infection. Here we show that consistent with the vaccinia virus (VACV) and cowpox virus (CPXV) requirement for cytoskeleton alterations early during the infection cycle, PBK/Akt was phosphorylated at S473 [Akt(S473-P)], a modification associated with the mammalian target of rapamycin complex 2 (mTORC2), which was paralleled by phosphorylation at T308 [Akt(T308-P)] by PI3K/PDK1, which is required for host survival. Notably, while VACV stimulated Akt(S473-P/T308-P) at early (1 h postinfection [p.i.]) and late (24 h p.i.) times during the infective cycle, CPXV stimulated Akt at early times only. Pharmacological and genetic inhibition of PI3K (LY294002) or Akt (Akt-X and a dominant-negative form of Akt-K179M) resulted in a significant decline in virus yield (from 80% to >/=90%). This decline was secondary to the inhibition of late viral gene expression, which in turn led to an arrest of virion morphogenesis at the immature-virion stage of the viral growth cycle. Furthermore, the cleavage of both caspase-3 and poly(ADP-ribose) polymerase and terminal deoxynucleotidyl transferase-mediated deoxyuridine nick end labeling assays confirmed that permissive, spontaneously immortalized cells such as A31 cells and mouse embryonic fibroblasts (MEFs) underwent apoptosis upon orthopoxvirus infection plus LY294002 treatment. Thus, in A31 cells and MEFs, early viral receptor-mediated signals transmitted via the PI3K/Akt pathway are required and precede the expression of viral antiapoptotic genes. Additionally, the inhibition of these signals resulted in the apoptosis of the infected cells and a significant decline in viral titers.

Cowpox immunomodulation of a pulmonary immune response to OVA‐peptide

Cowpox virus (CPXV), a close relative of the deadly variola virus causing smallpox, is primarily a lung pathogen and is known to transmit through aerosols. Prior work in our lab suggests that CPXV suppresses dendritic cell function in vitro and leaves them unable to stimulate T cells. We have developed an in vivo murine model system to directly assess the impact of an ongoing pulmonary CPXV infection on the response to a second antigen entering the lungs (OVA323‐339 peptide). Using adoptively transferred DO11.10 T cells that respond to OVA peptide, we have shown that a lethal CPXV infection reduces DO11.10 T cell proliferation in the lung‐associated lymph node (LALN), while proliferation can still occur during a sublethal infection. DCs in the LALN of CPXV infected mice have decreased expression of co‐stimulatory molecules CD80 and CD86 as well as CD1d, a lipid antigen presentation molecule. The number of infected DCs may account for the difference seen in sublethal and lethal infections. Using recombinant CPXV expressing enhanced green fluorescent protein, we determined that 32% of lung DCs are infected at the lethal dose of virus (day 6 post‐infection), while only 6% of DCs are infected at the sublethal dose. This may explain the difference in DO11.10 T cell proliferation using the two doses of virus, and the importance of functioning DCs in the lung to prevent against secondary infection in the pulmonary CPXV model.

Keeping an Eye on Poxviruses

On the basis of descriptions of the skin lesions, there were two major candidates for the diagnosis. The first candidiate was chickenpox, which is caused by a highly contagious human-adapted herpesvirus, and is endemic in central Africa, where immunization rates are low. The second candidiate was monkeypox, a zoonosis caused by an orthopoxvirus maintained in local rodents, which usually occurs as single cases, but can also produce short chains of person-to-person transmission. Although monkeypox has been observed with increasing frequency in the neighboring Democratic Republic of the Congo over the past four decades, it has only been reported once previously in the Republic of the Congo in a 2003 outbreak described by the same group of investigators. 2–4 In the present instance, MacNeil and others found that serum samples from approximately 40 of the villagers showed evidence of recent chickenpox, but their test results also identified three people who may have been exposed to monkeypox virus. This report reflects the increasing sophistication of efforts to detect the occurrence of poxviral zoonoses, which also include cowpox virus infection. Why is it important to monitor these diseases, which are barely known to most of the public health community? Their relative obscurity in part reflects the fact that, before the eradication of smallpox, vaccination with vaccinia virus largely prevented their occurrence, by crossprotecting against other members of the genus Orthopoxvirus . 5 However, now that most of the world’s population has never been vaccinated, there is no longer an immune barrier to keep these agents from crossing over from their reservoir species into the human population. Monkeypox is the disease of greatest concern because it closely resembles smallpox, but it is less contagious and has a lower case-fatality rate. 2 Although it has presumably occurred in central Africa for millenia, monkeypox was only discovered in 1970 during the course of the smallpox eradication campaign in Zaire (the present Democratic Republic of the Congo), when a smallpox-like illness developed in an infant in a rural village that could not be linked to any chain of person-to-person transmission. Because all other members of her family and most of the surrounding population had been vaccinated, it was initially feared that the child had contracted smallpox directly from an animal reservoir, potentially dooming efforts to eradicate the disease. 6,7 However, the agent isolated from her skin lesions proved to be monkeypox virus, which had been discovered 12 years earlier when it caused an outbreak of smallpox-like disease in monkeys in a holding facility in Copenhagen, Denmark. Field studies over the subsequent decade identified some 150 additional cases of human monkeypox in central and west Africa, principally in Zaire, and indicated that squirrels and perhaps other rodents were the natural reservoir. Because the disease appeared to pose little threat to the local population and none to the outside world, vaccination was halted in Zaire in 1980. 7