Destruction of variola virus: memorandum from a WHO meeting.

Memoranda! Memorandums Destruction of variola virus: Memorandum from a WHO meeting* This Memorandum discusses the fate of variola virus stocks which have been kept in two WHO Collab- orating Centres, as well as cloned DNA fragments of variola virus genome, smallpox vaccine, and seed vaccinia virus for the production of this vaccine. General and specific recommendations are given concerning destruction of variola virus; storage, distribution and handling of cloned DNA fragments of variola virus genome; and about stocks of smallpox vaccine. The eradication of smallpox during the late 1970s is among the greatest public health achievements of all time. This success resulted from an unprecedented intemational effort coordinated by WHO and was recognized by the 33rd World Health Assembly which declared on 8 May 1980 the global eradication of smallpox. Since the global eradication of smallpox, the stock of variola viruses has been gradually reduced and is now restricted to two WHO Collaborating Centres on Smallpox and other Poxvirus Infections, designated at the Centers for Disease Control and Prevention, Atlanta, GA, USA, and at the Institute for Viral Preparations, Moscow, Russian Federation. The members of the Committee on Orthopox- virus Infections, at a meeting in March 1986, unani- mously recommended the destruction of the virus * This Memorandum is based on the report of a WHO meeting of the Ad Hoc Committee on Orthopoxvirus Infections held in Geneva on 9 September 1994. The participants at the meeting were: I. Arita (Kumamoto City, Japan); K. Banerjee (Pune, India); W. Dowdle (Atlanta, GA, USA); K. Dumbell (Cape Prov- ince, South Africa); J. Esposito (Atlanta, GA, USA); F. Fenner (Chairman) (Canberra City, Australia); P.J. Greenaway (Rappor- teu) (London, England); D.A. Henderson (Washington, DC, USA); B.W.J. Mahy (Atlanta, GA, USA); S.S. Marennikova (Kolt- sovo, Russian Federation); H.G. Schatzmayr (Rio de Janeiro, Brazil). WHO Secretariat: K. Esteves, Y. Ghendon, R.H. Hender- son, L.J. Martinez, G. Torrigiani. Requests for reprints of this article should be sent to Pro- gramme on Bacterial, Viral Diseases and Immunology, Division of Communicable Diseases, World Health Organization, 1211 Geneva 27, Switzerland. A French translation of this article will appear in a later issue of the Bulletin. Reprint No. 5539 stocks kept in the two laboratories (1). In connection with this recommendation, the Committee noted that the variola gene pool could be cloned into non- expressing sites of bacterial plasmids for future stud- ies of variola virus and that archival records of vario- la virus would be satisfied by such cloned DNA. The Committee also considered that the cloned DNA would provide sufficient reference material to resolve any future diagnostic problem involving sus- pected smallpox. The meeting of the Ad Hoc Committee on Orthopoxvirus Infections in December 1990 con- firmed the recommendation and proposed a deadline of 31 December 1993 for the destruction (2). The Committee recommended that, in the meantime, the complete nucleotide sequence of the genome of at least one variola virus strain should be determined. The Committee considered that the sequence infor- mation might represent a useful and potentially safer record than the cloned material for archival purposes. The WHO Technical Committee on the Analysis of Nucleotide Sequences of Variola Virus Genomes reviewed the data obtained in the sequencing project at a meeting in January 1994. This Committee acknowledged that the information obtained in the project exceeded the minimum requested by WHO. The publication of the Ad Hoc Committee's rec- ommendation to destroy the variola viruses had, however, triggered mixed reactions from both the public and the scientific community. Diverging views attracted the attention of the media and were the subject of letters received in WHO from con- cemed individuals. The question was therefore given a frank and open airing in a round-table discussion Bulletin of the World Health Organization, 1994, 72 (6): 841-844 © World Health Organization 1994 841 Memorandum organized in August 1993 in conjunction with the IX International Congress of Virology in Glasgow, Scotland, where scientists representing the two opposing opinions were invited to make their views public. Variola virus stocks The Ad Hoc Committee, at its meeting on 9 Septem- ber 1994, considered the arguments for and against the destruction of the variola virus stocks, which are summarized below. Arguments against destruction: * All possibility of future studies on the variola virus will be lost (properties of viral genes and pro- teins, biological functions of the virus, pathogenesis, etc). * Destruction of the viruses in the two known repos- itories may not guarantee the complete removal of the virus from the Earth (preserved corpses of small- pox cases, forgotten or hidden stocks elsewhere). It was suggested that destruction should be agreed in principle, but should be postponed to allow more time for further analysis of the sequenced genomes of variola virus and for weighing of scien- tific merits when further advances in methods and understanding had occurred. Arguments for destruction: * The escape of the variola virus from the laborato- ries would be a serious risk because an increasing proportion of the global population lacks immunity to the disease owing to cessation of vaccination and revaccination against smallpox more than 10 years ago. * The sequence information and the availability of cloned DNA fragments of the full genome of several strains of variola virus allow most scientific ques- tions about the properties of the viral genes and pro- teins to be resolved. The cloned DNA fragments of the virus genome are non-infectious and can be handled in safety. * The decision to eradicate smallpox was a collec- tive decision of the world community, based on pub- lic health considerations and all measures should be taken to ensure that smallpox does not again afflict mankind. The members of the Ad Hoc Committee on Orthopoxvirus Infections discussed in detail the issues relating to the destruction of the last stocks of variola virus. They agreed that the scientific argu- ments for retention were clear and that there was some potential for learning more about the virus, its virulence and pathogenicity; not all desirable studies could be done with cloned virus DNA. The lack of a convenient laboratory animal and the need to work in high security (P4) facilities, however, limited the potential of such work. Those favouring early destruction of the virus indicated that many of the scientific questions raised could be better addressed by using other orthopoxviruses, or were of lower pri- ority than a variety of issues pertaining to agents still causing widespread disease. It was noted that the sci- entific community had been consulted widely and that many supported destruction including the Exec- utive Board of the International Union of Microbio- logical Societies, the Presidium of the Russian Acad- emy of Medical Sciences, the Council of the American Microbiological Society, and the Board of Directors of the American Type Culture Collection. The Committee unanimously agreed that all remaining stocks of variola virus should be destroyed, including whitepox virus, viral genomic DNA, clinical specimens and other materials con- taining infectious variola virus held in the WHO Collaborating Centres for Smallpox and other Poxvi- rus Infections in the Centers for Disease Control and Prevention, Atlanta, GA, USA, and in the Institute for Viral Preparations, Moscow, Russian Federation. There was debate over the date on which destruction should occur. Those favouring early destruction considered that the genomic sequence data from several strains of variola virus, with the availability of other sequences cloned in bacterial plasmids, satisfied the need for an archival record of the virus. They noted that these cloned DNA frag- ments would provide sufficient reference material to resolve any future diagnostic problem involving sus- pected smallpox and allowed for future studies of properties of variola virus genes and proteins. They also stressed that escape of variola virus from the laboratory would be a serious risk to the increasing proportion of the population that lacks immunity to smallpox. They noted that the decision to eradicate smallpox was a collective decision of the world com- munity, based on public health considerations, and health officials and others in many countries were concerned about the continued retention of stocks of variola virus, especially as some of these countries had made considerable efforts to destroy their own variola virus stocks. Members of the Ad Hoc Committee in favour of postponing destruction of the virus recommended that the archival storage of variola virus be continued in the two Collaborating Centres. They considered that the rapid advances in science and technology now occurring would enable new questions to be addressed in the future and that it was therefore too WHO Bulletin OMS. Vol 72 1994842 Destruction of variola virus early to take this irrevocable step. They urged that serious consideration be given to storing the virus for a further five years. The majority (8/10) of the members of the Ad Hoc Committee on Orthopoxvirus Infections recom- mended that the date for the destruction of the remaining stocks of variola virus and other materials as listed above should be on Friday 30 June 1995 in both Centres, subject to agreement by the World Health Assembly in May 1995. Cloned DNA fragments of variola virus genome The Ad Hoc Committee revised the recommendation of the last meeting about destruction of all recombi- nant materials that contain variola virus DNA sequences. Taking into account that cloned DNA fragments of variola virus genome are themselves not infectious and provide a useful resource and tool for analysing variola virus genes and protein structu- re and function, the majority (9/10) of the members of the Ad Hoc Committee recommended that such cloned material should be kept. The Committee also recommended the establishment of two intemational repositories for the storage, maintenance, distribution and monitoring of the cloned DNA fragments of variola virus genome - one at the WHO Collabora- ting Centre for Smallpox and Other Poxvirus Infec- tions, Centers for Disease Control and Prevention, Atlanta, GA, USA and the second at the Russian State Research Centre of Virology and Biotech- nology, Koltsovo, Novosibirsk Region, Russian Federation. The Committee recommended that special meas- ures should be adopted for the handling of cloned DNA fragments of variola virus genome, as follows: - All work with cloned DNA fragments containing variola virus genetic information (greater than 100 nucleotides long) should only be done fol- lowing a written risk assessment and in accor- dance with locally agreed national guidelines. - The insertion of variola virus genome sequences into genetic material of other orthopoxviruses is prohibited. No other orthopoxviruses should be handled in the laboratory rooms where material containing cloned variola virus genome sequen- ces are studied. - All by-products containing cloned DNA frag- ments of variola virus genomes and other related materials must be disposed of by autoclaving at 120 °C for 30 minutes. Smallpox vaccine The Ad Hoc Committee revised the recommenda- tions of the fourth meeting of the Committee on Orthopoxvirus Infections, which was held in 1986, regarding the elimination of the emergency stock of smallpox vaccine and retention of the seed virus stock for preparation of the vaccine. The Committee recommended that the 500000 doses of smallpox vaccine, currently in storage at -20 °C at WHO, should be retained indefinitely and be retested for potency every five years. The Ad Hoc Committee recommended that the Lister Elstree strain of vaccinia virus should continue to be kept as the smallpox vaccine seed virus stock. It was also recommend that the seed virus, in quan- tities of about 3 litres, should be kept at -20 °C by the WHO Collaborating Centre for Smallpox Vac- cine at the National Institute of Public Health and Environmental Protection, Bilthoven, Netherlands. Recommendations (1) The members of the Ad Hoc Committee unani- mously recommended that all stocks of variola virus should be destroyed by autoclaving followed by inci- neration, including all whitepox viruses, clinical spe- cimens, and other materials containing infectious variola virus or viral genomic DNA, held in the WHO Collaborating Centres for Smallpox and other Poxvirus Infections at the Centers for Disease Control and Prevention, Atlanta, GA, USA, and the Moscow Institute for Viral Preparations, Moscow, Russian Federation. Subject to agreement by the World Health Assembly, the majority view (8/10 members) was that destruction should occur in both Centres on Friday, 30 June 1995. A minority view (2/10 members) was that destruction of variola virus stocks should be delayed for a maximum of five years for scientific studies. (2) Variola virus genomic DNA should be destroyed in all laboratories holding such material when the variola viruses are destroyed in the Collaborating Centres for Smallpox and other Poxvirus Infections. (3) The certificate signed by WHO Commission members attesting that the variola virus stocks have been destroyed and the confirming statement of the Director of the Institute should be transmitted to the World Health Organization by the most senior health official of the Russian Federation and the USA. The certificate and the statement should be accompanied by an attestation, signed by that health official, affirming that there are in the country no known WHO Bulletin OMS. Vol 72 1994 843 Memorandum remaining strains of variola virus, clinical specimens, or uncloned viral genomic DNA. (4) The majority of the Ad Hoc Committee (9/10) recommended that stocks of cloned fragments of var- iola virus DNA should be retained. Two designated WHO International Repositories for the storage, maintenance, distribution and monitoring of the cloned DNA fragments of variola virus genome at the Centers for Disease Control and Prevention, Atlanta, GA, USA and 'at the Russian State Research Centre of Virology and Biotechnology, Koltsovo, Novosibirsk Region, Russian Federation should be established. Each repository should hold a duplicate set of archived material. Requests for access to these stocks should be made through WHO headquarters and the stocks should only be released under speci- fied conditions which guarantee that they will be handled under nationally agreed guidelines. Work should not be done in laboratory rooms that are con- currently handling orthopoxviruses. Insertion of vari- ola virus genome sequences into genetic material of other orthopoxviruses is prohibited. (5) The Centers for Disease Control and Prevention, Atlanta, GA, USA should publish their detailed pro- tocols for undertaking validated tests for differentiat- ing variola major and Alastrim strains from each other and from other orthopoxviruses. (6) A prioritized programme of work should be undertaken before 30 June 1995 to obtain certain additional DNA sequences, and to complete the clon- ing of DNA for the Garcia-1966 strain of variola virus. Sets of clones containing variola DNA sequences should be prepared and fully archived for distribution to the designated repositories. The Com- mittee hopes that DNA sequences for other species of orthopoxviruses will be obtained by laboratories interested in poxvirus studies. (7) A stock of smallpox vaccine (500000 doses) should continue to be kept by WHO headquarters in case of emergency. This should be stored at -20 °C and retitrated every 5 years. (8) Smallpox vaccine seed virus (vaccinia virus strain Lister Elstree) should continue to be kept at -20 °C by the WHO Collaborating Centre for Small- pox Vaccine at the National Institute for Public Health and Environmental Protection, Bilthoven, Netherlands. Seed virus should be tested every 5 years and, if necessary, additional passages of seed virus should be done at this Institute. (9) These recommendations should be submitted for consideration at the 95th Executive Board meeting (January 1995) and at the 48th World Health Assem- bly (May 1995). References 1. Orthopoxviruses. Bulletin of the World Health Orga- nization, 1986, 64: 801-802. 2. Report of the Ad Hoc Committee on Orthopoxvirus Infections. Unpublished WHO document No. CDS/ SME/91.1, 1991. 844 WHO Bulletin OMS. Vol 72 1994