Long-lasting stability of Vaccinia virus strains in murine feces: implications for virus circulation and environmental maintenance

Stability of Monkeypox Virus in Body Fluids and Wastewater

An outbreak of human mpox infection in nonendemic countries appears to have been driven largely by transmission through body fluids or skin-to-skin contact during sexual activity. We evaluated the stability of monkeypox virus (MPXV) in different environments and specific body fluids and tested the effectiveness of decontamination methodologies. MPXV decayed faster at higher temperatures, and rates varied considerably depending on the medium in which virus was suspended, both in solution and on surfaces. More proteinaceous fluids supported greater persistence. Chlorination was an effective decontamination technique, but only at higher concentrations. Wastewater was more difficult to decontaminate than plain deionized water; testing for infectious MPXV could be a helpful addition to PCR-based wastewater surveillance when high levels of viral DNA are detected. Our findings suggest that, because virus stability is sufficient to support environmental MPXV transmission in healthcare settings, exposure and dose-response will be limiting factors for those transmission routes.

Lung microbiome of stable and exacerbated COPD patients in Tshwane, South Africa

Chronic obstructive pulmonary disease (COPD) is characterised by the occurrence of exacerbations triggered by infections. The aim of this study was to determine the composition of the lung microbiome and lung virome in patients with COPD in an African setting and to compare their composition between the stable and exacerbated states. Twenty-four adult COPD patients were recruited from three hospitals. Sputum was collected and bacterial DNA was extracted. Targeted metagenomics was performed to determine the microbiome composition. Viral DNA and RNA were extracted from selected samples followed by cDNA conversion. Shotgun metagenomics sequencing was performed on pooled DNA and RNA. The most abundant phyla across all samples were Firmicutes and Proteobacteria. The following genera were most prevalent: Haemophilus and Streptococcus. There were no considerable differences for alpha and beta diversity measures between the disease states. However, a difference in the abundances between disease states was observed for: (i) Serratia (3% lower abundance in exacerbated state), (ii) Granulicatella (2.2% higher abundance in exacerbated state), (iii) Haemophilus (5.7% higher abundance in exacerbated state) and (iv) Veillonella (2.5% higher abundance in exacerbated state). Virome analysis showed a high abundance of the BeAn 58058 virus, a member of the Poxviridae family, in all six samples (90% to 94%). This study is among the first to report lung microbiome composition in COPD patients from Africa. In this small sample set, no differences in alpha or beta diversity between stable and exacerbated disease state was observed, but an unexpectedly high frequency of BeAn 58058 virus was observed. These observations highlight the need for further research of the lung microbiome of COPD patients in African settings.

Twenty Years after Bovine Vaccinia in Brazil: Where We Are and Where Are We Going?

Orthopoxvirus (OPV) infections have been present in human life for hundreds of years. It is known that Variola virus (VARV) killed over 300 million people in the past; however, it had an end thanks to the physician Edward Jenner (who developed the first vaccine in history) and also thanks to a massive vaccination program in the 20th century all over the world. Although the first vaccine was created using the Cowpox virus (CPXV), it turned out later that the Vaccinia virus was the one used during the vaccination program. VACV is the etiological agent of bovine vaccinia (BV), a zoonotic disease that has emerged in Brazil and South America in the last 20 years. BV has a great impact on local dairy economies and is also a burden to public health. In this review, we described the main events related to VACV and BV emergence in Brazil and South America, the increase of related scientific studies, and the issues that science, human and animal medicine are going to face if we do not be on guard to this virus and its disease.

Safety, biodistribution and viral shedding of oncolytic vaccinia virus TG6002 administered intravenously in healthy beagle dogs

Oncolytic virotherapy is an emerging strategy that uses replication-competent viruses to kill tumor cells. We have reported the oncolytic effects of TG6002, a recombinant oncolytic vaccinia virus, in preclinical human xenograft models and canine tumor explants. To assess the safety, biodistribution and shedding of TG6002 administered by the intravenous route, we conducted a study in immune-competent healthy dogs. Three dogs each received a single intravenous injection of TG6002 at 105 PFU/kg, 106 PFU/kg or 107 PFU/kg, and one dog received three intravenous injections at 107 PFU/kg. The injections were well tolerated without any clinical, hematological or biochemical adverse events. Viral genomes were only detected in blood at the earliest sampling time point of one-hour post-injection at 107 PFU/kg. Post mortem analyses at day 35 allowed detection of viral DNA in the spleen of the dog which received three injections at 107 PFU/kg. Viral genomes were not detected in the urine, saliva or feces of any dogs. Seven days after the injections, a dose-dependent antibody mediated immune response was identified. In conclusion, intravenous administration of TG6002 shows a good safety profile, supporting the initiation of clinical trials in canine cancer patients as well as further development as a human cancer therapy.

Here, There, and Everywhere: The Wide Host Range and Geographic Distribution of Zoonotic Orthopoxviruses

The global emergence of zoonotic viruses, including poxviruses, poses one of the greatest threats to human and animal health. Forty years after the eradication of smallpox, emerging zoonotic orthopoxviruses, such as monkeypox, cowpox, and vaccinia viruses continue to infect humans as well as wild and domestic animals. Currently, the geographical distribution of poxviruses in a broad range of hosts worldwide raises concerns regarding the possibility of outbreaks or viral dissemination to new geographical regions. Here, we review the global host ranges and current epidemiological understanding of zoonotic orthopoxviruses while focusing on orthopoxviruses with epidemic potential, including monkeypox, cowpox, and vaccinia viruses.

Safety studies and viral shedding of intramuscular administration of oncolytic vaccinia virus TG6002 in healthy beagle dogs

BACKGROUND

Cancer is a leading cause of mortality for both humans and dogs. As spontaneous canine cancers appear to be relevant models of human cancers, developing new therapeutic approaches could benefit both species. Oncolytic virotherapy is a promising therapeutic approach in cancer treatment. TG6002 is a recombinant oncolytic vaccinia virus deleted in the thymidine kinase and ribonucleotide reductase genes and armed with the suicide gene FCU1 that encodes a protein which catalyses the conversion of the non-toxic 5-fluorocytosine into the toxic metabolite 5-fluorouracil. Previous studies have shown the ability of TG6002 to infect and replicate in canine tumor cell lines, and demonstrated its oncolytic potency in cell lines, xenograft models and canine mammary adenocarcinoma explants. Moreover, 5-fluorouracil synthesis has been confirmed in fresh canine mammary adenocarcinoma explants infected with TG6002 with 5-fluorocytosine. This study aims at assessing the safety profile and viral shedding after unique or repeated intramuscular injections of TG6002 in seven healthy Beagle dogs.

RESULTS

Repeated intramuscular administrations of TG6002 at the dose of 5 × 10⁷ PFU/kg resulted in no clinical or biological adverse effects. Residual TG6002 in blood, saliva, urine and feces of treated dogs was not detected by infectious titer assay nor by qPCR, ensuring the safety of the virus in the dogs and their environment.

CONCLUSIONS

These results establish the good tolerability of TG6002 in healthy dogs with undetectable viral shedding after multiple injections. This study supports the initiation of further studies in canine cancer patients to evaluate the oncolytic potential of TG6002 and provides critical data for clinical development of TG6002 as a human cancer therapy.

Seroprevalence and Risk Factors Possibly Associated with Emerging Zoonotic Vaccinia Virus in a Farming Community, Colombia

Dairy farmers had high rates of orthopoxvirus seropositivity and substantial illness associated with vaccinia-like lesions.

In 2014, vaccinia virus (VACV) infections were identified among farmworkers in Caquetá Department, Colombia; additional cases were identified in Cundinamarca Department in 2015. VACV, an orthopoxvirus (OPXV) used in the smallpox vaccine, has caused sporadic bovine and human outbreaks in countries such as Brazil and India. In response to the emergence of this disease in Colombia, we surveyed and collected blood from 134 farmworkers and household members from 56 farms in Cundinamarca Department. We tested serum samples for OPXV antibodies and correlated risk factors with seropositivity by using multivariate analyses. Fifty-two percent of farmworkers had OPXV antibodies; this percentage decreased to 31% when we excluded persons who would have been eligible for smallpox vaccination. The major risk factors for seropositivity were municipality, age, smallpox vaccination scar, duration of time working on a farm, and animals having vaccinia-like lesions. This investigation provides evidence for possible emergence of VACV as a zoonosis in South America.

Bovine Vaccinia: Insights into the Disease in Cattle

Bovine vaccinia (BV), caused by Vaccinia virus (VACV), is a zoonosis characterized by exanthematous lesions in the teats of dairy cows and the hands of milkers and is an important public health issue. Severe VACV-induced lesions in the teats and udder of cows and buffaloes could lead to mastitis and other secondary infections, thereby reducing productivity and resulting in economic losses to the dairy industry. In Brazil, BV re-emerged in the late 1990s and is now endemic in most of the Brazilian territory. In the last 15 years, much effort has been made to know more about this disease and its epidemiology, etiologic agents, and interactions with the host and the environment. In this review, we describe the known dynamics of VACV infection in cattle and the viral shedding routes, as well as the relevance of BV for animal and public health.

Vaccinia virus in Feces and Urine of Wild Rodents from São Paulo State, Brazil

The origin of Vaccinia virus (VACV) outbreaks in Brazil remains unknown, but since the isolation of VACV in Mus musculus mice during a zoonotic outbreak affecting cattle and milkers, peridomestic rodents have been suggested to be a link between cows and wild animals. Considering that experimentally infected mice eliminate viral particles in their feces, we investigated the presence of VACV in the feces and urine of wild rodents that were captured in the forest areas surrounding milking farms in the central west region of São Paulo State. For the first time, this work reports the detection of VACV by PCR in the feces of naturally infected Oligoryzomys flavescens, Oligoryzomys nigripes, and Sooretamys angouya, and in the urine of Oligorizomys flavescens, which raises important questions about the spread of VACV by rodent feces and its potential to induce clinical infections in cows.

Vaccinia Virus in Blood Samples of Humans, Domestic and Wild Mammals in Brazil

Outbreaks of Vaccinia virus (VACV) affecting cattle and humans have been reported in Brazil in the last 15 years, but the origin of outbreaks remains unknown. Although VACV DNA have been already detected in mice (Mus musculus), opossums (Didelphis albiventris) and dogs during VACV zoonotic outbreaks, no transmission to cattle or humans from any of these were reported during Brazilian outbreaks. In this work, we assessed the PCR positivity to VACV in blood samples of cows and other domestic mammals, wild rodents and other wild mammals, and humans from areas with or without VACV infection reports. Our results show the detection of VACV DNA in blood samples of cows, horse and opossums, raising important questions about VACV spread.

Vaccinia Virus Natural Infections in Brazil: The Good, the Bad, and the Ugly

The orthopoxviruses (OPV) comprise several emerging viruses with great importance to human and veterinary medicine, including vaccinia virus (VACV), which causes outbreaks of bovine vaccinia (BV) in South America. Historically, VACV is the most comprehensively studied virus, however, its origin and natural hosts remain unknown. VACV was the primary component of the smallpox vaccine, largely used during the smallpox eradication campaign. After smallpox was declared eradicated, the vaccination that conferred immunity to OPV was discontinued, favoring a new contingent of susceptible individuals to OPV. VACV infections occur naturally after direct contact with infected dairy cattle, in recently vaccinated individuals, or through alternative routes of exposure. In Brazil, VACV outbreaks are frequently reported in rural areas, affecting mainly farm animals and humans. Recent studies have shown the role of wildlife in the VACV transmission chain, exploring the role of wild rodents as reservoirs that facilitate VACV spread throughout rural areas. Furthermore, VACV circulation in urban environments and the significance of this with respect to public health, have also been explored. In this review, we discuss the history, epidemiological, ecological and clinical aspects of natural VACV infections in Brazil, also highlighting alternative routes of VACV transmission, the factors involved in susceptibility to infection, and the natural history of the disease in humans and animals, and the potential for dissemination to urban environments.

Serologic and Molecular Evidence of Vaccinia Virus Circulation among Small Mammals from Different Biomes, Brazil

Vaccinia virus (VACV) is a zoonotic agent that causes a disease called bovine vaccinia, which is detected mainly in milking cattle and humans in close contact with these animals. Even though many aspects of VACV infection have been described, much is still unknown about its circulation in the environment and its natural hosts/reservoirs. To investigate the presence of Orthopoxvirus antibodies or VACV DNA, we captured small rodents and marsupials in 3 areas of Minas Gerais state, Brazil, and tested their samples in a laboratory. A total of 336 animals were tested; positivity ranged from 18.1% to 25.5% in the 3 studied regions located in different biomes, including the Atlantic Forest and the Cerrado. Analysis of nucleotide sequences indicated co-circulation of VACV groups I and II. Our findings reinforce the possible role played by rodents and marsupials in VACV maintenance and its transmission chain.

Subclinical bovine vaccinia: An important risk factor in the epidemiology of this zoonosis in cattle

Bovine vaccinia (BV) is a zoonosis caused by Vaccinia virus (VACV) that mainly affects lactating cows and dairy farm milkers. The epidemiological role(s) of other cattle categories such as dry cows, bulls, and heifers in BV remains unclear. This study was performed to investigate VACV in affected dairy cattle herds and perifocal farms during an outbreak in Brazil. Crusts from lesions of cows' teats were collected from all farms with BV outbreaks. Milk, feces, blood, and serum were collected from symptomatic and asymptomatic lactating cows. Blood and serum were also sampled from other cattle categories (calves, heifers, dry cows, and bulls). The samples were tested for VACV by PCR, and to confirm VACV viability, VACV-positive samples were inoculated in BSC-40 cells and stained using immunoperoxidase. Neutralizing antibodies were investigated using plaque reduction neutralization test. Viral DNA was detected in milk, blood, and feces samples of symptomatic and asymptomatic dairy cows and in blood samples from other cattle categories on farms with and without confirmed BV outbreak. In affected farms, viable virus was identified in feces and milk samples from lactating cows and in blood samples from asymptomatic dry cows. Viable VACV was also identified in feces from lactating cows and one bull's blood sample from perifocal farms. Neutralizing antibodies were detected in 81.6% of the herds affected by BV and in 53.8% of the herds on perifocal farms. The presented data indicate a potential source of viral dissemination, which contributes to the persistence and spread of VACV in the environment.

Molecular evidence of Orthopoxvirus DNA in capybara (Hydrochoerus hydrochaeris) stool samples

Vaccinia virus (VACV) is responsible for outbreaks in Brazil and has immense potential as an emerging virus. VACV can be found naturally circulating in India, Pakistan and South America, where it causes infections characterised by exanthematic lesions in buffaloes, cattle and humans. The transmission cycle of Brazilian VACV has still not been fully characterised; one of the most important gaps in knowledge being the role of wild animals. Capybaras, which are restricted to the Americas, are the world's largest rodents and have peculiar characteristics that make them possible candidates for being part of a natural VACV reservoir. Here, we developed a method for detecting orthopoxvirus DNA in capybara stool samples, and have described for the first time the detection of orthopoxvirus DNA in capybaras samples from three different regions in Brazil. These findings strongly suggest that capybaras might be involved in the natural transmission cycle of VACV and furthermore represent a public health problem, when associated with Brazilian bovine vaccinia outbreaks. This makes infected animals an important factor to be considered when predicting and managing Brazilian VACV outbreaks.

Vaccinia virus Transmission through Experimentally Contaminated Milk Using a Murine Model

Bovine vaccinia (BV) is a zoonosis caused by Vaccinia virus (VACV), which affects dairy cattle and humans. Previous studies have detected the presence of viable virus particles in bovine milk samples naturally and experimentally contaminated with VACV. However, it is not known whether milk contaminated with VACV could be a route of viral transmission. However, anti-Orthopoxvirus antibodies were detected in humans from BV endemic areas, whom had no contact with affected cows, which suggest that other VACV transmission routes are possible, such as consumption of contaminated milk and dairy products. Therefore, it is important to study the possibility of VACV transmission by contaminated milk. This study aimed to examine VACV transmission, pathogenesis and shedding in mice orally inoculated with experimentally contaminated milk. Thirty mice were orally inoculated with milk containing 107 PFU/ml of VACV, and ten mice were orally inoculated with uncontaminated milk. Clinical examinations were performed for 30 consecutive days, and fecal samples and oral swabs (OSs) were collected every other day. Mice were euthanized on predetermined days, and tissue and blood samples were collected. Nested-PCR, plaque reduction neutralization test (PRNT), viral isolation, histopathology, and immunohistochemistry (IHC) methods were performed on the collected samples. No clinical changes were observed in the animals. Viral DNA was detected in feces, blood, OSs and tissues, at least in one of the times tested. The lungs displayed moderate to severe interstitial lymphohistiocytic infiltrates, and only the heart, tonsils, tongue, and stomach did not show immunostaining at the IHC analysis. Neutralizing antibodies were detected at the 20th and 30th days post infection in 50% of infected mice. The results revealed that VACV contaminated milk could be a route of viral transmission in mice experimentally infected, showing systemic distribution and shedding through feces and oral mucosa, albeit without exhibiting any clinical signs.

Safety and biodistribution of a double-deleted oncolytic vaccinia virus encoding CD40 ligand in laboratory Beagles

We evaluated adverse events, biodistribution and shedding of oncolytic vaccinia virus encoding CD40 ligand in two Beagles, in preparation for a phase 1 trial in canine cancer patients. Dog 1 received one dose of vaccinia virus and was euthanized 24 hours afterwards, while dog 2 received virus four times once weekly and was euthanized 7 days after that. Dogs were monitored for adverse events and underwent a detailed postmortem examination. Blood, saliva, urine, feces, and organs were collected for virus detection. Dog 1 had mild fever and lethargy while dog 2 experienced a possible seizure 5.5 hours after first virus administration. Viral DNA declined quickly in the blood after virus administration in both dogs but was still detectable 1 week later by quantitative polymerase chain reaction. Only samples taken directly after virus infusion contained infectious virus. Small amounts of viral DNA, but no infectious virus, were detected in a few saliva and urine samples. Necropsies did not reveal any relevant pathological changes and virus DNA was detected mainly in the spleen. The dogs in the study did not have cancer, and thus adverse events could be more common and viral load higher in dogs with tumors which allow viral amplification.

Serological study of vaccinia virus reservoirs in areas with and without official reports of outbreaks in cattle and humans in São Paulo, Brazil

Vaccinia virus (VACV), the etiological agent of an exanthematic disease, has been associated with several bovine outbreaks in Brazil since the end of the global vaccination campaign against smallpox. It was previously believed that the vaccine virus used for the WHO global campaign had adapted to an unknown wild reservoir and was sporadically re-emerging in outbreaks in cattle and milkers. At present, it is known that Brazilian VACV is phylogenetically different from the vaccinia virus vaccinal strain, but its origin remains unknown. This study assessed the seroprevalence of orthopoxviruses in domestic and wild animals and farmers from 47 farms in three cities in the southwest region of the state of São Paulo with or without official reports of outbreaks in cattle or humans. Our data indicate a low seroprevalence of antibodies in wild animals and raise interesting questions about the real potential of wild rodents and marsupials as VACV reservoirs, suggesting other routes through which VACV can be spread.

Clinical, hematological and biochemical parameters of dairy cows experimentally infected with Vaccinia virus

Vaccinia virus (VACV) is the etiological agent of bovine vaccinia (BV), an important zoonosis that affects dairy cattle. There are many aspects of the disease that remain unknown, and aiming to answer some of these questions, the clinical, hematological, and biochemical parameters of VACV experimentally infected cows were evaluated. In the first part of the study, lactating cows were infected with VACV-GP2 strain. In the second part, animals previously infected with VACV-GP2 were divided into two treatment groups: Group 1, immunosuppressed cows; and Group 2, re-infected cows. In this study, BV could be experimentally reproduced, with similar lesions as observed in natural infections. Moreover, a short incubation period and local lymphadenopathy were also observed. VACV could be detected by PCR and isolated from scabs taken from teat lesions of all inoculated and re-inoculated animals. Lymphocytosis and neutrophilia were observed in all animals from the first part of the experiment, and lymphopenia and relative neutrophilia were observed in the immunosuppressed animals. Detection of viral DNA in oral mucosa lesions suggests that viral reactivation might occur in immunosuppressed animals. Moreover, clinical disease with teat lesions may occur in previously VACV-infected cows under the experimental conditions of the present study.

Vaccinia viruses isolated from skin infection in horses produced cutaneous and systemic disease in experimentally infected rabbits

The susceptibility of rabbits to two isolates of Vaccinia virus (VACV) recovered from cutaneous disease in horses in Southern Brazil was investigated. Rabbits were inoculated in the ear skin with both VACV isolates, either in single or mixed infection. All inoculated animals presented local skin lesions characterized by hyperaemia, papules, vesicles, pustules and ulcers. Infectious virus was detected in the lungs and intestine of rabbits that died during acute disease. Histological examination of the skin revealed changes characteristic of those associated with members of the genus Orthopoxvirus. These results demonstrate that rabbits develop skin disease accompanied by systemic signs upon intradermal inoculation of these two equine VACV isolates, either alone or in combination, opening the way for using rabbits to study selected aspects of the biology and pathogenesis of VACV infection.

Vaccinia viruses isolated from cutaneous disease in horses are highly virulent for rabbits

Two genotypically distinct Vaccinia viruses (VACV), named P1V and P2V, were isolated from an outbreak of cutaneous disease in horses in Southern Brazil. We herein investigated the susceptibility of rabbits, a proposed animal model, to P1V and P2V infection. Groups of weanling rabbits were inoculated intranasally (IN) with P1V or P2V at low (10(2.5) TCID50), medium (10(4.5)TCID50), or high titer (10(6.5)TCID50). Rabbits inoculated with medium and high titers shed virus in nasal secretions and developed serous to hemorrhagic nasal discharge and severe respiratory distress, followed by progressive apathy and high lethality. Clinical signs appeared around days 3-6 post-inoculation (pi) and lasted up to the day of death or euthanasia (around days 5-10). Virus shedding and clinical signs were less frequent in rabbits inoculated with low virus titers. Viremia was detected in all groups, with different frequencies. Viral DNA was detected in the feces of a few animals inoculated with P1V and P2V, low titer, and with P2V at high titer. Gross necropsy findings and histological examination showed diffuse interstitial fibrousing pneumonia with necrosuppurative bronchopneumonia and intestinal liquid content. Neutralizing antibodies were detected in all inoculated animals surviving beyond day 9 pi. These results show that rabbits are highly susceptible to VACV isolated from horses, and develop severe respiratory and systemic disease upon IN inoculation. Thus, rabbits may be used to study selected aspects of VACV infection and disease.

Filling one more gap: experimental evidence of horizontal transmission of Vaccinia virus between bovines and rodents

Vaccinia virus (VACV) has been associated with several exanthematic outbreaks in bovine, human, and equine species in Brazilian rural areas. Little is known about VACV reservoirs, although it is believed that rodents could be associated with VACV outbreaks. With the goal of filling one more gap in the VACV ecological puzzle, the present work aimed at mimicking a potential transmission route of VACV between cows and rodents, both known as natural VACV hosts. Balb/c mice were exposed to feces of experimentally VACV infected cows for 20 days, and samples from these mice were examined by using molecular and serological tests. VACV DNA was detected in feces and blood samples after several days of exposure; infectious VACV particles were also detected in the feces. The presence of anti-VACV neutralizing antibodies in murine sera further suggested horizontal transmission. If the transmission model described here can be applied to natural environments, exposure to bovine feces could be considered a risk factor for the spread of VACV; consequently, the traditional use of bovine manure as a fertilizer in agricultural activities may be promoting the infection of rodents.

Susceptibility of Vaccinia virus to chemical disinfectants

Vaccinia virus (VACV) is the cause of bovine vaccinia (BV), an emerging zoonotic disease that affects dairy cows and milkers. Some chemical disinfectants have been used on farms affected by BV to disinfect cow teats and milkers' hands. To date, there is no information about the efficacy of disinfectants against VACV. Therefore, this study aimed to assess the virucidal activity of some active disinfectants commonly used in the field. Sodium hypochlorite, quaternary ammonium combined with chlorhexidine, and quaternary ammonium combined with glutaraldehyde were effective in inactivating the virus at all concentrations tested. Iodine and quaternary ammonium as the only active component were partially effective. The presence of bovine feces as organic matter and light decreased the effectiveness of sodium hypochlorite. These results show that an appropriated disinfection and asepsis of teats and hands may be helpful in the control and prevention of BV and other infections with VACV.

Zoonotic Brazilian Vaccinia virus: from field to therapy

Vaccinia virus (VACV), the prototype species of the Orthopoxvirus (OPV) genus, causes an occupational zoonotic disease in Brazil that is primarily associated with the handling of infected dairy cattle. Cattle and human outbreaks have been described in southeastern Brazil since 1999 and have now occurred in almost half of the territory. Phylogenetic studies have shown high levels of polymorphisms among isolated VACVs, which indicate the existence of at least two genetically divergent clades; this has also been proven in virulence assays in a mouse model system. In humans, VACV infection is characterized by skin lesions, primarily on the hands, accompanied by systemic symptoms such as fever, myalgia, headache and lymphadenopathy. In this review, we will discuss the virological, epidemiological, ecological and clinical aspects of VACV infection, its diagnosis and compounds that potentially could be used for the treatment of severe cases.

Vaccinia virus is not inactivated after thermal treatment and cheese production using experimentally contaminated milk

Bovine vaccinia is an emergent zoonosis caused by the Vaccinia virus (VACV). The disease is characterized by the appearance of exanthematic lesions that occur in humans and dairy cows. Previous studies have revealed the presence of infectious viral particles in milk samples during an outbreak of bovine vaccinia in Brazil, indicating the possibility of disease transmission through raw milk. To assess the viability of the virus in milk after thermal treatment and processing procedures, milk samples were experimentally contaminated with 10(3) plaque forming units (PFU)/mL (group I) and 10(5) PFU/mL (group II) VACV Guarani P2 virus, and the third group was not contaminated and served as a control. The samples were submitted to storage temperatures in a cold chamber, freezer for 48 hours, and to low temperature long-time treatment. Moreover, the viral viability was evaluated in cheese produced with contaminated milk using 10(4) PFU/mL VACV Guarani P2. Notably, the virus remained viable in milk after storage for 48 hours in both the cold chamber and the freezer, with a reduction in viral titer of 14.49% and 25.86%, respectively. Group II showed a viral reduction in titer of 61.88% and 75.98%, respectively. Thermal treatment 65°C for 30 minutes showed a reduction of viral titer of 94.83% and 99.99%, respectively, in group I and group II, but still showed remaining viable virus particles. In addition, it was possible to recover infectious viral particles from both the solid curds and the whey of the cheese produced with experimentally contaminated milk. The cheese shows a reduction in viral titer of 84.87% after storage at 4°C for 24 hours. The presence of viable viral particles in milk after both thermal treatment and cheese production indicates a potential public health risk.