Historical review of smallpox, the eradication of smallpox and the attenuated smallpox MVA vaccine]

After the WHO had declared smallpox to be eradicated in 1980, smallpox vaccination ceased to be carried out in humans all over the world. The cutaneous inoculations carried out with live vaccines based on the vaccinia virus from 1798 onwards protected both the global population and, indirectly, the animals living with humans against orthopox infections in general. A large percentage of humans and animals no longer enjoy this protection. Idiopathic orthopox in animals (reservoir possibly rats and mice) are thus experiencing a renaissance, posing a threat to humans and animals. The paper provides an historical retrospective of smallpox epidemics in humankind, their course of development and methods employed to combat this disease, commencing long before the birth of Christ with primitive attempts in China and India and from the end of the 18th century with increasingly enhanced methods, most recently with worldwide smallpox vaccination programmes using live vaccinia vaccines. Smallpox vaccination was always accompanied by a variety of complications, especially postvaccinal encephalitis. The MVA strain was developed to reduce or prevent such adverse effects. MVA has meanwhile proved its worth both as a parenteral vaccine against orthopox infections in humans and animals and as a vector for insertion of foreign genes. The history of smallpox, the fight against this disease and the development of MVA are documented with the help of figures and tables.     

Poxviruses as vaccine vectors

The discovery of Jenner in 1798 founded the science of immunology and eventually led to smallpox eradication from the earth in 1980 after a world-wide vaccination campaign with vaccinia virus (another poxvirus) and paradoxically, despite the eradication of smallpox, there has been an explosion of interest in vaccinia virus in the eighties. This interest has stemmed in part from the application of molecular genetics to clone and express foreign genes from recombinant vaccinia viruses. Vaccinia is also gaining renewed interest due to bioterrorism.

These recombinant viruses have multiple applications in research and vaccinology and led to the development of vectored vaccines, such as the recombinant vaccinia rabies vaccine used to eliminate rabies in Western Europe and, more recently, in the United States. Secondly, alternative poxvirus vectors, such as avipox viruses, were proved to be even safer and efficacious non-replicating vectors (suiciole vectors) when used in non-avian species.     

Substitution of vaccinia virus Elstree by modified vaccinia virus Ankara to test the virucidal efficacy of chemical disinfectants

After the eradication of variola in 1980, the smallpox vaccination was considered to be no longer required and was subsequently abandoned mainly because of possible adverse effects of vaccinia virus especially in first‐time vaccinees. Despite a growing number of humans without immunity against vaccinia virus, vaccinia virus Lister Elstree (VACV) is still prescribed for testing virucidal efficacy of chemical disinfectants in the guidelines of the German Veterinary Medical Society [Deutsche Veterinärmedizinische Gesellschaft (DVG)], the German Association for the Control of Virus Diseases [Deutsche Vereinigung zur Bekämpfung der Viruskrankheiten (DVV)] and the Robert Koch Institute (RKI). To evaluate a possible substitution of VACV, with the attenuated modified vaccinia virus Ankara (MVA) the virucidal efficacy of four different DVG‐listed commercially available chemical disinfectants representing different groups of chemicals was tested against these two viruses. Quantitative suspension tests and qualitative carrier tests with poplar wood and gauze were performed. Distinction of VACV and MVA was confirmed by cytopathogenic effects, such as differences in plaque morphology. No significant difference in disinfection efficacy between VACV and MVA was observed for any of the disinfectants tested. Implying that vaccinia virus poses a risk after inadvertent inoculation, our results show that MVA, which does not replicate in humans, should replace VACV in the chemical disinfectant testing guidelines.     

Animal poxviruses transmitted from cat to man: current event with lethal end.

We report about the infection of an 18-year-old man with an orthopox virus (OPV) which was transmitted by a cat. The infectious route from cat to man could be proved by epidemiological, virological and serological methods. The corresponding techniques are described. The patient had not been vaccinated against smallpox and was intensively immunosuppressed by medication on account of a severe endogeneous eczema combined with an allergic asthma bronchiale. A cyclic poxvirus disease developed with a generalised, partly confluent pox virus exanthema disseminated over the body. The clinical symptoms were similar to a "variola pustulosa haemorrhagica". The young man died of a lung embolism in the course of the intensive medical therapy. The haemorrhagic character of the pox virus pustules with central necrosis (pox navel) could be reproduced in the rabbit skin and on chorioallantois membranes. The pox virus isolated from the patient could be differentiated from variola, vaccinia and monkeypox virus. It is a member of the group of "cowpox-like viruses". The environmental importance of these OPVs is discussed.     

Fish and chips

Summary

Generalized cowpox infection in the Patagonian cavy may represent a threat to the health of immunocompromised persons. We report the first case of cowpoxvirus infection in the Patagonian cavy in an educational animal park. The mara developed extensive pox lesions, shedding large amounts of viral particles. The ending of vaccination programmes against smallpox in the late 1970's may lead to an increase in susceptibility of humans to zoonotic poxviruses.     

Taking advantage of the positive side-effects of smallpox vaccination

From the introduction of smallpox vaccination approximately 200 years ago right up to its discontinuation (1980), reports by physicians and scientists about positive side-effects such as healing of chronic skin rashes, reduced susceptibility to various infectious diseases, e.g. measles, scarlet fever and whooping cough, and even the prophylactic use of the vaccination, e.g. against syphilis, were published again and again. Comparison with the period after cessation of vaccination confirms the experiences of the above vaccinators. As early as 1956, targeted research on these observations led to evidence of the 'ring-zone phenomenon', i.e. the production of soluble antiviral substances in infected chicken embryos and cell cultures. With the help of modern immunological and bioengineering methods, it was later possible to demonstrate that these effects are based on the activation of lymphoreticular cells and the regulatory effect of certain cytokines within the context of the non-specific immune system. These findings led to the development of paramunization with paraspecific vaccines from highly attenuated animal pox viruses. During attenuation, deletions in the virus DNA occur. Attenuated animal pox strains are therefore suited for the production of vector vaccines. The fact that these vector vaccines demonstrate an especially high level of paraspecific efficacy and lack harmful effects is likewise the result of the attenuated animal pox viruses. Optimum regulation of the entire immune system leads to increased paramunity already in the first few days after vaccination and to enhanced antigen recognition and thus accelerated commencement of specific immunity.     

Experimental detection of the paraspecific effects of purified and inactivated poxviruses

The paraspecific effect of pox viruses i.e. stimulation of the nonspecific part of the complex immune system, was demonstrated in vitro and in vivo for 3 different types of virus (vaccinia virus, avipox virus, parapox virus). By means of purification, concentration and inactivation, it was possible to prove that the paraspecific effect is brought about by the pox virus particle per se. The effect is induced by certain epitopes in the complex structure of the virus and is independent of virus multiplication. Both purified pox viruses and inactivated, purified pox viruses stimulate NK cell activity, the CSA and the formation of interferon, and reach higher efficacy indices in a challenge test with baby mice using stomatitis vesicularis virus than non-purified and non-inactivated cell culture material. The degree of purity of the pox virus preparations was established using the electron microscope and monoclonal antibodies. The purified and concentrated pox virus preparations proved to be pyrogen-free; they were not toxic to baby mice in vivo. An endotoxin-induced effect could be ruled out. The broad paraspecific effect of pox viruses and their structural components lends itself to use as paramunity inducers in prophylaxis and therapy.     

Immune response of chicks to oral vaccination against Newcastle disease and fowl pox

The humoral immune response and immunity conferred in chicks were compared following separate and combined oral vaccination with F strain of Newcastle disease virus (NDV) and HP1 strain of fowl pox virus. The haemagglutination inhibition (HI) antibody titre against NDV and passive haemagglutination (PHA) antibody titre against fowl pox virus were comparable in two respective groups. The serum IgG concentration increased significantly after the second vaccination in all the groups. The NDV vaccine induced significantly higher IgG production as compared to fowl pox virus vaccine. There was no significant difference in serum IgG concentration produced by combined vaccine and separate F strain vaccine. The protection afforded by combined and separate vaccinations did not vary significantly against challenge with virulent strains of NDV and fowl pox virus at different stages.     

Taking Advantage of the Positive Side‐Effects of Smallpox Vaccination

From the introduction of smallpox vaccination approximately 200 years ago right up to its discontinuation (1980), reports by physicians and scientists about positive side‐effects such as healing of chronic skin rashes, reduced susceptibility to various infectious diseases, e.g. measles, scarlet fever and whooping cough, and even the prophylactic use of the vaccination, e.g. against syphilis, were published again and again. Comparison with the period after cessation of vaccination confirms the experiences of the above vaccinators. As early as 1956, targeted research on these observations led to evidence of the ‘ring‐zone phenomenon’, i.e. the production of soluble antiviral substances in infected chicken embryos and cell cultures. With the help of modern immunological and bioengineering methods, it was later possible to demonstrate that these effects are based on the activation of lymphoreticular cells and the regulatory effect of certain cytokines within the context of the non‐specific immune system. These findings led to the development of paramunization with paraspecific vaccines from highly attenuated animal pox viruses. During attenuation, deletions in the virus DNA occur. Attenuated animal pox strains are therefore suited for the production of vector vaccines. The fact that these vector vaccines demonstrate an especially high level of paraspecific efficacy and lack harmful effects is likewise the result of the attenuated animal pox viruses. Optimum regulation of the entire immune system leads to increased paramunity already in the first few days after vaccination and to enhanced antigen recognition and thus accelerated commencement of specific immunity.     

羊痘的研究进展

羊痘病毒能引起山羊痘、绵羊痘和牛的结节性疹块病。羊痘是以发热、全身性的皮肤损伤、痘疹和淋巴结病变为特征。羊痘病毒是所有动物痘病毒中最为重要的一种，严重影响养羊业和国际贸易的发展。本文从病原学、流行病学、诊断和预防控制等方面对羊痘做一综述。虽然此病从临床症状和宿主特异性上很容易做出诊断，但进一步的实验室确诊还是必要的，现已有多种检测方法和诊断试剂。控制该病最有效的方法还是使用疫苗对易感动物进行免疫接种。     

金丝雀痘诊断与痘病毒致弱试验

本试验对送检的金丝雀经实验室诊断，确认为金丝雀痘，对分离的痘病毒进行动物致病性试验、病毒分离传代和致试验、致弱毒保护力试验和返强试验。结果表明：金丝雀痘病毒经鸡胚盲传３后能适鸡胚并致死金丝雀，８代后无致病性，１３例毒性快速通过本动物３次无返强现象，金丝雀用第１３代毒刺种３０天能抵抗强毒攻击。     

Responses of cattle, sheep and poultry to a recombinant vaccinia virus expressing a swine influenza haemagglutinin

Groups of cattle, sheep and poultry were inoculated with a recombinant vaccinia virus expressing the haemagglutinin of the swine influenza virus A/NJ/11/76. No adverse clinical responses were recorded and none of the animals developed a viraemia when inoculated with the recombinant or wild-type vaccinia virus. Recombinant virus reisolated from lesions in cattle was stable, maintaining its thymidine kinase negative phenotype and ability to express the swine influenza haemagglutinin. Antibodies to the influenza haemagglutinin were detected in cattle, sheep and poultry inoculated with the recombinant virus. While no animals inoculated with wild-type virus developed these antibodies, there was no detectable spread of either recombinant or wild-type virus from the inoculation sites or to in-contact uninoculated animals. The results indicate that recombinant vaccinia viruses can induce immune responses in cattle, sheep and poultry demonstrating their potential as vaccine vectors in a variety of important veterinary species.     

New emerging viral zoonoses

New developments in the field of viral transmission from animal to man can be divided into four areas of study. First are the new viral zoonoses such as diseases caused by rotaviruses, Lassa virus and the animal orthopox viruses which will be more prevalent after the cessation of mandatory vaccination against smallpox. Secondly are the numerous ubiquitous viruses, such as adeno and herpesviruses, which in healthy animals lead only to clinically inapparent infections. A typical example of the third area is the recombination and hybridisation between animal and human influenza type A viruses. The final area is concerned with the transmission of viral zoonoses to man through food of animal origin.     

In ovo vaccination of specific-pathogen-free chickens with vaccines containing multiple agents.

We used in ovo technology to protect chickens against multiple diseases by inoculating vaccines containing mixtures of live viral agents. A single in ovo injection of a vaccine containing serotypes 1, 2, and 3 of Marek's disease virus (MDV), a vaccine strain of serotype 1 infectious bursal disease virus (IBDV), and recombinant fowl pox vaccine with HN and F genes of Newcastle disease virus (rFP-NDV) induced protection against virulent MDV, IBDV, Newcastle disease virus, and fowl poxvirus. The multiple-agent vaccine induced specific antibodies against the viral agents present in the mixture and did not adversely affect the survival of hatched chickens. Inoculation of a vaccine containing serotypes 1, 2, and 3 of MDV and IBDV did not affect hatchability of eggs, although the addition of rFP-NDV to the mixture reduced hatchability by 23%-26%. In ovo vaccination with a vaccine containing MDV and IBDV vaccine viruses did not exacerbate the inhibitory effect of individual viral agents on humoral and cellular immune competence.     

Cowpoxvirus infection in the Patagonian cavy (Dolichotis patagonum) emerging disease in an educational animal park the first reported case

Generalized cowpox infection in the Patagonian cavy may represent a threat to the health of immunocompromised persons. We report the first case of cowpoxvirus infection in the Patagonian cavy in an educational animal park. The mara developed extensive pox lesions, shedding large amounts of viral particles. The ending of vaccination programmes against smallpox in the late 1970's may lead to an increase in susceptibility of humans to zoonotic poxviruses.     

The effect of aging on immune responses.

Although vaccine manufacturers make no specific recommendations regarding the vaccination of older horses and ponies, the similarities in age-induced immunologic changes between human beings and equids suggests that similar vaccination recommendations should be followed. The need for vaccination of the older horse depends, of course, on the relative risk of exposure for the individual horse. Particular care should be taken when using attenuated vaccine products because these live agents may pose a unique risk to the older individual. Immunization with inactivated agent vaccines is likely to be safer. In general, annual vaccination against equine influenza virus infection, tetanus, rabies, and encephalomyelitis viruses is warranted.     

尼帕病毒研究进展

尼帕病毒(Nipah virus,NiV)是新近发现的引发脑部炎症或呼吸道疾病等重症的新型人畜共患病病毒,该病毒最初于1999年马来西亚尼帕镇的1名脑炎患者脑脊液中分离获得,至今已经历了数次大的流行,造成严重的经济损失和人员伤亡.该病毒可由动物传播给人,也可直接人与人传播,并且能够在猪等动物身上引起严重疾病,狐蝠科的果蝠是该病毒的天然宿主.NiV感染人后的病死率极高,并且目前还没有有效的疫苗和治疗措施,生物危害性极大,被列为生物安全4级病原(BSL4).笔者从NiV的分类及分型、基因和蛋白质组、流行和分布、疫苗研制、临床和病理变化以及实验室诊断技术等方面对NiV做简单的概述.     

Do postvaccinal sarcomas occur in Australian cats ?

SUMMARY: A soft tissue sarcoma occurred in the interscapular area of a cat, 1 to 7 months after vaccination at that site. The vaccine contained inactivated feline panleucopaenia virus combined with modified live feline herpesvirus and calicrvirus. The tumour showed histological features of both fibrosarcoma and malignant fibrous histiocytoma. The tumour was observed to evolve from the site of a presumed postvaccinal granuloma. Local recurrence 6 weeks post excision necessitated more radical resection. Euthanasia was performed 2 years later when pleural effusion developed. The cause of effusion was not determined. There was no palpable evidence of local tumour regrowth at the time of euthanasia. A causal relationship between vaccination and sarcoma formation is considered based on the temporal association between the two events, the anatomical location of the tumour and histopathology consistent with postvaccinal sarcomas reported overseas. Six other vaccine site fibrosarcomas, potentially vaccine associated using the above criteria, are summarised.     

山羊痘病毒NM株的分离鉴定

从内蒙古牛场疑似山羊痘病毒感染的病羊中分离到1株病毒,命名为NM株。取病羊的皮肤痘疹和水疱作病料样品,分别接种BHK-21传代细胞和10日龄SPF鸡胚。结果表明,BHK-21细胞出现了明显的、规律的细胞病变,鸡胚接种部位出现了明显的痘斑;NM株细胞毒和胚毒均能够被山羊痘病毒阳性血清所抑制。利用1对山羊痘病毒特异性检测引物对NM株病毒进行PCR扩增,获得445 bp片段,与预期大小一致。将扩增产物提纯后克隆至pMD18-T载体,经酶切鉴定正确后,对阳性克隆株进行序列测定,结果表明,NM株的基因片段与已发表的山羊痘病毒毒株的相应基因片段具有高度同源性,同源性在99.2%~100%之间。