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The word "pox" indicated, during the late 15th century, a disease characterized by eruptive sores. When an outbreak of syphilis began in Europe during that time, it was called by many names, including the French term "la grosse verole" ("the great pox"), to distinguish it from smallpox, which was termed "la petite verole" ("the small pox"). Chickenpox was initially confused with smallpox until 1767, when the English physician William Heberden (1710-1801) provided a detailed description of chickenpox, differentiating it from smallpox. The cowpox virus was used by Edward Jenner (1749-1823) to develop a successful vaccine against smallpox. He devised the term "variolae vaccinae" ("smallpox of the cow") to denote cowpox. Jenner's pioneering work on a smallpox vaccine has led to the eradication of this disease and opened the way to preventing other infectious diseases, such as monkeypox, a poxvirus that is closely related to smallpox and that is currently infecting persons around the world. This contribution tells the stories behind the names of the various "poxes" that have infected humans: the great pox (syphilis), smallpox, chickenpox, cowpox, and monkeypox. These infectious diseases not only share a common "pox" nomenclature, but are also closely interconnected in medical history., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Mass vaccination has played a critical role in the global eradication of smallpox. Various vaccinia virus (VACV) strains, whose origin has not been clearly documented in most cases, have been used as live vaccines in different countries. These VACV strains differed in pathogenicity towards various laboratory animals and in reactogenicity exhibited upon vaccination of humans. In this work, we studied the development of humoral and cellular immune responses in BALB/c mice inoculated intranasally (i.n.) or intradermally (i.d.) with the VACV LIVP strain at a dose of 10 5 PFU/mouse, which was used in Russia as the first generation smallpox vaccine. Active synthesis of VACV-specific IgM in the mice occurred on day 7 after inoculation, reached a maximum on day 14, and decreased by day 29. Synthesis of virus-specific IgG was detected only from day 14, and the level increased significantly by day 29 after infection of the mice. Immunization (i.n.) resulted in significantly higher production of VACV-specific antibodies compared to that upon i.d. inoculation of LIVP. There were no significant differences in the levels of the T cell response in mice after i.n. or i.d. VACV administration at any time point. The maximum level of VACV-specific T-cells was detected on day 14. By day 29 of the experiment, the level of VACV-specific T-lymphocytes in the spleen of mice significantly decreased for both immunization procedures. On day 30 after immunization with LIVP, mice were infected with the cowpox virus at a dose of 46 LD 50 . The i.n. immunized mice were resistant to this infection, while 33% of i.d. immunized mice died. Our findings indicate that the level of the humoral immune response to vaccination may play a decisive role in protection of animals from orthopoxvirus reinfection.

In Europe, cowpox virus (CPXV) infection in South American camelids occurs as a so-called spill-over infection. Although infected animals generally have a mild form of the disease and survive, cases of fatal generalised CPXV infection have also been described. Prevention by prophylactic vaccination is the only way to protect animals from disease. In the present study, modified vaccinia virus Ankara (MVA) vaccine, which has been successfully used in many animal species, was used in a prime-boost vaccination regimen in two alpaca herds with a history of CPXV infection. The focus of the study was the prevention of further clinical cases, and to determine the safety and immunogenicity of the MVA vaccine in alpacas. The MVA vaccine was well tolerated and safe in the 94 animals vaccinated. An indirect immunofluorescence assay (IFA) using MVA as an antigen showed that the seroprevalence of antibody after booster vaccination was 81.3% in herd I and 91.7% in herd II. Detectable antibody titres declined to 15.6% in herd I and 45.8% in herd II over a 12-month period after booster vaccination. Animals could be divided into four groups based on individual antibody titres determined over one year: Group 1 consisted of 19.3% of animals that were seropositive until the end of the trial period; Group 2 consisted of 58.0% of animals that were seropositive after booster vaccination, but seronegative one year later; Group 3 consisted of 14.7% of animals that were not seropositive at any time point; and Group 4 consisted of 7.9% of animals that were seropositive after initial immunisation, seronegative six months later, but seropositive or intermediate in IFA one year after immunisation, likely because of natural exposure. In new-born crias born to MVA-vaccinated mares, specific maternal antibodies were detected in 50.0% of animals up to 14 weeks of age. Our results confirm that MVA vaccination is a feasible tool for the prevention of CPXV disease in alpacas. Long-term studies are needed to verify future vaccination regimen in CPXV affected herds.

Few papers have had a greater impact on the health of the human species than the simple, yet elegant, observations and clinical trials of Edward Jenner with what was at the time called the Cow Pox. In fact, this was a naturally attenuated rodent (probably rat) pox that could infect horses and, through farriers and farm hands, dairy cattle. While commonly called the Cow Pox at the time, Jenner's transmission studies between humans used infectious materials from horses. His methods provided protection from the serious effects of smallpox infections. In 1977, smallpox was considered to be eradicated, although people continue to be infected by pox viruses from other mammalian species. We consider this to be our 'favorite historical paper' because it emphasizes careful clinical observation followed by relatively simple clinical testing can have a profound influence on human health, even when almost nothing is known about the underlying molecular mechanisms. Continued follow-up with strict attention to detail resulted in a crude but effective way to deal with an epidemic, methods still used today for containing infectious diseases., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Vienna was the first city on the European continent where the cowpox vaccination was applied in 1799, shortly after Jenner's (1798) publication of his encouraging results in England. Nevertheless, substantial denial and distrust was evident among doctors and patients in Europe as well, particularly in Austria. The medical doctor Johann Gottfried Bremser remains well known even today among parasitologists as a pioneer of helminthological research in Austria. He founded, in Vienna, one of the richest parasitic worm collections worldwide and published perceptive papers about helminthology. But his role as a protagonist of the cowpox vaccine has been buried in oblivion. In the late 18th and early 19th centuries, Bremser worked as a medical doctor in Vienna and was influenced by the major proponents of the vaccine in Austria, Pascal Joseph Ferro, Jean de Carro, Johann Peter Frank and others. Beyond his practical contribution as vaccinator, he excelled as a propagandist, mainly through his publications on cow pox vaccination. Bremser used his expert knowledge and sophisticated argumentation to prompt people to accept the prophylactic treatment, especially for their children. He argued for an obligatory cowpox vaccination for all. On one hand, his argumentation summarizes the contrarian opinions of that time, on the other hand the discussion shows striking analogies with the controversies of today. In a way, Bremser's commitment was a forerunner for future health policies that led to vaccination laws and ultimately to the eradication of smallpox worldwide in the second half of the 20th century.

An adenovirus 5 vector encoding for mouse interferon alpha, subtype 5 (mDEF201) was evaluated for efficacy against lethal cowpox (Brighton strain) and vaccinia (WR strain) virus respiratory and systemic infections in mice. Two routes of mDEF201 administration were used, nasal sinus (5-µl) and pulmonary (50-µl), to compare differences in efficacy, since the preferred treatment of humans would be in a relatively small volume delivered intranasally. Lower respiratory infections (LRI), upper respiratory infections (URI), and systemic infections were induced by 50-µl intranasal, 10-µl intranasal, and 100-µl intraperitoneal virus challenges, respectively. mDEF201 treatments were given prophylactically either 24 h (short term) or 56d (long-term) prior to virus challenge. Single nasal sinus treatments of 10(6) and 10(7) PFU/mouse of mDEF201 protected all mice from vaccinia-induced LRI mortality (comparable to published studies with pulmonary delivered mDEF201). Systemic vaccinia infections responded significantly better to nasal sinus delivered mDEF201 than to pulmonary treatments. Cowpox LRI infections responded to 10(7) mDEF201 treatments, but a 10(6) dose was only weakly protective. Cowpox URI infections were equally treatable by nasal sinus and pulmonary delivered mDEF201 at 10(7) PFU/mouse. Dose-responsive prophylaxis with mDEF201, given one time only 56 d prior to initiating a vaccinia virus LRI infection, was 100% protective from 10(5) to 10(7) PFU/mouse. Improvements in lung hemorrhage score and lung weight were evident, as were decreases in liver, lung, and spleen virus titers. Thus, mDEF201 was able to treat different vaccinia and cowpox virus infections using both nasal sinus and pulmonary treatment regimens, supporting its development for humans.

Overview: The misnomer 'cowpox' has historical roots: cats rather acquire the virus from small rodents. It has a wide host spectrum (including man) and causes skin lesions, predominantly on the head and paws. Progressive proliferative ulcerations in kittens and immunosuppressed cats may take a fatal course. Cat owners should be informed about the zoonotic risk.

Purpose of Review: Human cowpox, a rare zoonotic infection, evokes a self-limited disease, except for immunocompromised and eczematous patients, particularly children, where it can become severe. The causative agent, cowpox virus, is distributed in Europe, west former USSR, and adjacent areas of Northern and Central Asia, with an increasing number of reports in Europe. The purpose of this paper is to review cowpox with an emphasis on its epidemiology and management., Recent Findings: Numerous reports of human cowpox affecting young people in Europe indicate that lack of smallpox vaccination, which has been abandoned since 1977, may render the population more vulnerable to cowpox virus. The ownership of wild and exotic animal pets is becoming more popular, and the range of recognized wild and domestic animal hosts is expanding,, Summary: Cowpox as a human emerging zoonotic hazard raises public health concerns as well as a question about the production of effective vaccine and antiviral agents.

It is now difficult to manufacture the first-generation smallpox vaccine, as the process could not comply with current safety and manufacturing regulations. In this study, a candidate non-clonal second-generation smallpox vaccine developed by Sanofi-Pasteur from the Lister strain has been assessed using a cowpox virus challenge in mice. We have observed similar safety, immunogenicity and protection (from disease and death) after a short or long interval following vaccination, as well as similar virus clearance post-challenge, with the second-generation smallpox vaccine candidate as compared to the traditional vaccine used as a benchmark.

An anti-poxvirus vaccine based on replicon particles of Venezuelan equine encephalitis virus (VRP) is being developed. The cowpox virus genes encoding structural proteins corresponding to vaccinia virus proteins A33, B5, and A27 were each expressed from VRP. High serum IgG titers against these proteins were generated in BALB/c mice vaccinated with each of these VRP. VRP induced both IgG1 and IgG2a with a strong predominance of IgG2a production. The response is long-lasting, as evidenced by the retention of high anti-B5 serum IgG titers through at least 50 weeks after priming immunization. Mice vaccinated with B5-, A33- or A27-VRP individually or together survived intranasal challenge with cowpox virus, with the multivalent vaccine formulation providing more effective protection from weight loss and clinical signs of illness than the monovalent vaccines. These results demonstrate that VRP may provide an effective alternative to vaccinia virus vaccines against poxvirus infection.

There have been virtually no studies of 'who acquires infection from whom' in wildlife populations, but patterns of transmission within and between different classes of host are likely to be reflected in the spatiotemporal distribution of infection among those host classes. Here, we use a modified form of K-function analysis to test for space-time interaction among bank voles and wood mice infectious with cowpox virus. There was no evidence for transmission between the two host species, supporting previous evidence that they act as separate reservoirs for cowpox. Among wood mice, results suggested that transmission took place primarily between individuals of the opposite sex, raising the possibility that cowpox is sexually transmitted in this species. Results for bank voles indicated that infected females might be a more important source of infection to either sex than are males. The suggestion of different modes of transmission in the two species is itself consistent with the apparent absence of transmission between species.

We employed a murine model to test the concept of using an aerosolized, long-acting antiviral drug to protect humans against smallpox. We previously showed that a low dose of aerosolized cidofovir (HPMPC [Vistide]) was highly protective against subsequent aerosolized cowpox virus challenge and was more effective than a much larger dose of drug given by injection, suggesting that aerosolized cidofovir is retained in the lung. Because the nephrotoxicity of cidofovir is a major concern in therapy, delivering the drug directly to the respiratory tract might be an effective prophylactic strategy that maximizes the tissue concentration at the site of initial viral replication, while minimizing its accumulation in the kidneys. In the present study, we found that treating mice with aerosolized (14)C-labeled cidofovir ((14)C-cidofovir) resulted in the prolonged retention of radiolabeled drug in the lungs at levels greatly exceeding those in the kidneys. In contrast, subcutaneous injection produced much higher concentrations of (14)C-cidofovir in the kidneys than in the lungs over the 96-h time course of the study. As further evidence of the protective efficacy of aerosolized cidofovir, we found that aerosol treatment before or after infection was highly protective in mice challenged intranasally with cowpox virus. All or nearly all mice that were treated once by aerosol, from 2 days before to 2 days after challenge, survived intranasal infection, whereas all placebo-treated animals died.

The Brighton strain of cowpox virus causes lethal bronchopneumonia when delivered as a small-particle (1 microm) aerosol to weanling BALB/c mice. We showed previously that this disease can be prevented or cured with one subcutaneous injection of cidofovir (HPMPC, Vistide). To determine whether even better results could be obtained by delivering the drug directly to the respiratory tract, we administered cidofovir by small-particle aqueous aerosol before or after aerosolized cowpox infection. In a series of five experiments, aerosol doses of 0.5-5 mg/kg were always more effective than 25 mg/kg and sometimes more effective than 100 mg/kg injected subcutaneously, as measured by changes in body and lung weight, lung viral titers, pulmonary pathology and survival. A cyclic analog ((1-[(S)-2-hydroxy-2-oxo-1,4,2-dioxaphosphorinan-5-yl)methyl] cytosine) (cHPMPC) was less protective. The results suggest that aerosolized cidofovir would be effective for prophylaxis or early post-exposure therapy of human smallpox or monkeypox virus infection.

The efficacy of cidofovir for treatment of cowpox virus infection in BALB/c mice was investigated in an effort to evaluate new therapies for virulent orthopoxvirus infections of the respiratory tract in a small animal model. Exposure to 2(-5)x10(6) pfu of cowpox virus by aerosol or intranasally (inl) was lethal in 3- to 7-week-old animals. One inoculation of 100 mg/kg cidofovir on day 0, 2, or 4, with respect to aerosol infection, resulted in 90%-100% survival. Treatment on day 0 reduced peak pulmonary virus titers 10- to 100-fold, reduced the severity of viral pneumonitis, and prevented pulmonary hemorrhage. The same dose on day -6 to 2 protected 80%-100% of inl infected mice, whereas 1 inoculation on day -16 to -8 or day 3 to 6 was partially protective. Cidofovir delayed but did not prevent the death of inl infected mice with severe combined immunodeficiency. Treatment at the time of tail scarification with vaccinia virus did not block vaccination efficacy.

Sylvatic rabies can be efficiently controlled by vaccination of foxes with a vaccinia-rabies recombinant virus. However, the risk of recombination between the engineered vaccine virus and other orthopoxviruses endemic in wildlife, such as cowpox virus, still needs to be investigated. In this study, foxes inoculated orally and intradermally with cowpox virus were found to be not very susceptible to cowpox virus, which was isolated from only the oropharynx and tonsils, at low titre and for only five days after inoculation. Thus the risk of recombination between these viruses in foxes is very low.

The immunological efficacy of vacciniavirus "MVA" was tested against a dermal and intradermal infection with cowpoxvirus "OPV 85" in rabbits: A single vaccination with "MVA" provided only insufficient immunity, a revaccination induced good immunity. Intramuscular immunizations protected better than subcutaneous applications. Immunized rabbits showed "revaccination reactions" after infection with "OPV 85" indicating a cellular immunity. After immunization with "MVA" and after infection with cowpoxvirus "OPV 85" all rabbits developed N- and ELISA-antibodies. HAI-antibodies were not found after immunization, but indicated a multiplication of cowpoxvirus after challenge. Vacciniavirus "MVA" is suggested for immunization of man and animal against possible infections with cowpoxvirus and cowpoxlike viruses.