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PubMed2000

[20 years without smallpox].

It is 20 years since the 33rd World Health Assembly (WHA) declared that "worldwide eradication of smallpox" was achieved. This was the outcome of many years intensive work of the World Health Organization (WHO) and its member countries. In 1958 the WHA adopted the recommendation that WHO should initiate the eradication of smallpox on a worldwide scale. In 1967 the eradication activities in hitherto endemic countries became more intense. Smallpox affected 31 countries and 15 countries recorded from occasional cases. Every year more than 10 million people contracted the disease and two million of them died. A ten-year limit for the eradication was set. Gradually smallpox were eradicated in South America, then in Asia and last in Africa where the last case of endemic smallpox was recorded in 1977 in Somalia. WHO ensured international collaboration, close coordination of activities and mobilization of financial, personal and material resources. It ensured also that tested methods were fully applied in the affected countries regardless of their political, religious and cultural differences. In the eradication activities participated hundreds of thousands of local and 700 health professionals from abroad, incl. 20 Czechoslovak epidemiologists. The worldwide costs of eradication amounted to some 300 million dollars, i.e. some 23 million per year. The most important contribution of the eradication of smallpox was in addition to the termination of human suffering, worldwide financial savings estimated to 1-2 billion US dollars per year. These saved personal and financial resources could be used for other important health projects. The eradication of variola was defined as eradication of clinical forms of smallpox not as the final eradication of the variola virus. The importance of laboratories keeping the variola virus increased steeply at the time when clinical cases of smallpox were eradicated. From the beginning of the eighties WHO made an effort to reduce their number to a minimum. Since 1984 strains of variola are officially kept only in two centres collaborating with WHO. The Organization suggested destruction of the kept viruses in 1987, i.e. ten years after the eradication of smallpox. Unfortunately some political and scientific circles did not agree with this intention. Even recommendations to destroy the virus in 1993 and again in 1999 were not accepted. In the nineties fear of bio-terrorism and secret modernization of biological weapons influenced some member countries to change their opinion on the intended destruction of the virus. Despite this in May 1999 the WHA adopted a resolution that the final destruction of all variola strains is the objective of all member countries of WHO and recommended to postpone the destruction of the virus to the year 2002. The reason for postponement is current research of new antiviral preparations and better vaccines. There is again hope that all that will be left of the variola virus will be magnetic signals on computer diskettes.

Bioterrorism↗
PubMedDate not supplied

Smallpox: gone but not forgotten.

Smallpox represents both the acme of man's efforts to combat infectious diseases and one of his greatest fears. The disease emerged in prehistoric times to spread throughout the world causing blindness and death in millions of people. An acute infection caused by variola virus, one of the Orthopoxviruses, with skin eruption and marked toxemia had an average case fatality rate of 30%. Variola minor, a milder form of the disease, had a case fatality of one percent. Humans are the sole host, and survival confers lifelong immunity. Immunization was practiced since ancient times by inoculation with the variola virus until Jenner's demonstration of the efficacy and safety of vaccination with vaccinia virus. Following an intensive eradication effort by the World Health Organization, the world was declared to be free of smallpox in 1979. The decision to destroy all remaining stocks of variola virus in 1999 has met with some controversy.

Animals↗
PubMed2005

Preparation of monoclonal antibodies cross-reactive with orthopoxviruses and their application for direct immunofluorescence test.

Variola virus (smallpox virus), vaccinia virus (VV), cowpox virus (CPV) and ectromelia virus (EV) belong to the genus Orthopoxvirus of the family Poxviridae. To establish the possible diagnosis for smallpox infection, monoclonal antibodies (MAbs) against VV and CPV were produced. The cross-reactivity of seven MAbs with cells infected with various strains of the orthopoxviruses (CPV, VV and EV) was confirmed by an immunofluorescence (IF) test and other immunological analyses. Four and three MAbs reacted with the common antigen of all poxviruses (probably NP antigen) and the antigen involved in neutralization, respectively. We developed the IF test using these MAbs. The direct IF test required only 45 min to perform. Smallpox infection is now eradicated, but it is important to prepare for the diagnosis of smallpox in an emergency. The direct IF assay using MAbs cross-reactive with orthopoxviruses is rapid, simple, specific, applicable for multiple samples, and will make it possible to screen for and detect orthopoxviruses that include variola virus with tissue impression smears from skin lesions in most laboratories or institutes.

Animals↗
PubMed1972

Poxviruses isolated from clinically ill and asymptomatically infected monkeys and a chimpanzee.

Poxviruses were isolated from the kidneys of an outwardly healthy chimpanzee trapped in an area of the Democratic Republic of the Congo where a case of monkeypox had recently occurred in man, from the kidneys of clinically healthy cynomolgus monkeys in a colony in the Netherlands, and from monkeys suffering from monkeypox during outbreaks in colonies in the USA. It was established that two of the three viruses isolated from animals asymptomatically infected-namely, strain Chimp-9 from the chimpanzee and strain 64-7255 from the cynomolgus monkeys-although similar to one another differed markedly from the classical Copenhagen strain of monkeypox virus. These two viruses were characterized by the formation of small, monomorphic, well-defined pocks without haemorrhages on infected chick embryo chorioallantoic membrane, by the small plaques of the proliferative type that they produced in cell cultures, by the absence of reactions when they were applied to scarified rabbit skin and the absence of marked necrosis when they were inoculated intradermally into rabbits, by their intensive replication in pig embryo kidney cell cultures, and by a number of other features. It is therefore possible to describe both the viruses as being very close to the variola virus. The Chimp-9 and 64-7255 strains differed from the variola virus only in their greater pathogenicity for white mice after intracerebral inoculation. The other virus isolated from a symptomless cynomolgus monkey-strain 64-9411-resembled the two viruses isolated from monkeys suffering from monkeypox and did not differ from the Copenhagen strain.

Animals↗
PubMed2005

Interferon function is not required for recovery from a secondary poxvirus infection.

IFN function is critical for recovery from most primary viral infections, including poxvirus infection. In contrast, very little is known about the requirement for IFN function in mediating recovery from a secondary virus infection. We have used ectromelia virus (ECTV), an orthopoxvirus very closely related to variola virus, to investigate the importance of IFN function in recovery from a secondary infection. Variola virus, the causative agent of smallpox in humans, and ECTV, which causes mousepox in mice, both encode receptor homologs that are thought to interfere with host IFN function. Using a prime-challenge regime, in which avirulent ECTV is used to prime mice deficient in type I/II IFN function or IFN regulatory factor 1 (IRF-1) and then challenging the mice with a virulent strain, we show that IFN function is redundant for virus clearance during a secondary ECTV infection. A neutralizing Ab response is generated in a secondary infection, even in the absence of IFN function, although when present, IFN strongly influences the neutralizing titer and subtype of IgG that is produced. Importantly, the depletion of CD8+ T lymphocytes during a secondary challenge in IFN-deficient mice does not affect their capacity to clear ECTV, indicating that Ab is critical for the control of a secondary infection.

Animals↗
PubMed1977

[Determination of autohemolysin formation using the plaque test. Demonstration of autoimmune phenomena following vaccinations and infections].

A simple and sensitive modification of the plaque assay for the evaluation of autohaemolysin-producing cells (APC) in the peripheral blood is described: Very small chambers, (volume less than or equal to 0.03 cc) made out of glass slides (75 X 25 mm), are filled with a diluted (1:7) blood cell suspension. After incubation for 26 hours the haemolytic plaques produced by APC in the thin monolayer of blood cells can be counted under the microcope at a magnification up to 320-fold. The number of APC in guinea pigs immunized with cholera vaccine and in monkeys infected with variola-virus was evaluated by means of this method. Cholera vaccination significantly raised the APC up to 7 days after immunization. In monkeys these cells increased markedly between 4 and 7 days after infection with variola-virus. The increase was less pronounced in animals partially protected by prior vaccination with attenuated vaccinia-virus (MVA-strain) and showing a mild course of variola. Autoimmune mechanisms may exist in apparently normal organisms. They may rise after tissue destruction or cell alteration by infectious or other exogenous agents. The method described might be useful to determine the degree of reactogenicity of bacterial and viral vaccines.

Animals↗
PubMed1998

Two major antigenic polypeptides of molluscum contagiosum virus.

A library of molluscum contagiosum virus (MCV) transferred into the cowpox vector expression system was screened with 12 sera from molluscum patients. Two recombinant proteins of 70 and 34 kDa were detected by immunoblotting and mapped to the open-reading frames MC133L and MC084L, respectively. Consensus sites were found between the C-terminus of the 70-kDa MCV protein and the 14-kDa fusion protein of vaccinia and variola virus, and between the 34-kDa MCV protein and the 37.5-kDa viral membrane-associated protein of vaccinia and variola virus. Rabbit antisera against these two proteins were prepared. An immunofluorescence study demonstrated that the 70- and 34-kDa proteins were predominantly expressed on the surface of recombinant virus-infected HeLa cells, indicating the potential to be inserted into the membrane. On immunoelectron microscopy, antiserum against 70-kDa protein showed significant labeling of the MCV membrane, while the antiserum against 34-kDa protein failed to do so.

Amino Acid Sequence↗