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PubMed1994

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 Collaborating 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.

DNA, Viral↗
PubMed1957

Survival of variola virus in raw cotton.

An investigation was carried out to establish the survival period of variola virus in relation to its importation into Great Britain in raw cotton. Under the conditions of the experiments described here, variola virus in scabs from a single patient survived for a maximum of three to four months at a relative humidity of 58, and for only two to four months at 30 degrees C and humidities of 73 and 84. Exposed virus in the form of vesicle fluid in capillaries did not survive for three months at this temperature in any of these humidities.These results suggest that variola virus in scabs or seeds in tropical climates-i.e., at temperatures of from 30 degrees C to 40 degrees C or higher-is unlikely to survive for as long as six months. Thus, if the period of storage of cotton were at least six months after ginning and before shipment from cotton-producing countries in the tropics where smallpox is endemic, the chances of importation of viable variola virus on raw cotton into areas free from infection would be very small. However, if cotton can become contaminated with smallpox scabs in temperate climates (20 degrees -25 degrees C) or is already contaminated when imported at this temperature, the experiments indicate that a few particles of virus may survive for as long as 18 months. The virus can, of course, survive for many years, ten or more, at from 4 degrees C to 5 degrees C in closed tubes or bottles, with little decrease in titre.

Cotton Fiber↗
PubMed1992

Independent evolution of monkeypox and variola viruses.

Smallpox was eradicated more than 10 years ago, but infection with another Orthopoxvirus, monkeypox virus, can result in a clinical picture resembling smallpox. Human infection with monkeypox virus is extremely rare, not easily transmitted, and confined to the rain forest belt of Africa (Z. Jezek and F. Fenner, p. 81-102, in Human Monkeypox, 1988). Evidence that variola virus, the causative agent of smallpox, might be readily derived from monkeypox virus was presented [S. S. Marennikova and E. M. Shelukhina, Nature (London) 276:291-292, 1978; S. S. Marennikova, E. M. Shelukhina, N. N. Maltseva, and G. R. Matsevich Intervirology 11:333-340, 1979], but this was not confirmed [K. R. Dumbell and L. C. Archard, Nature (London) 286:29-32, 1980] and was subsequently discounted (J. J. Esposito, J. H. Nakano, and J. F. Obijeski, Bull. W.H.O. 63:695-703, 1985). Although enough difference between the genomes of monkeypox and variola viruses to rule out a simple interconversion has been demonstrated [K. R. Dumbell and L. C. Archard, Nature (London) 286:29-32, 1980; J. J. Esposito and J. C. Knight, Virology 143:230-251, 1985; J. J. Esposito, J. H. Nakano, and J. F. Obijeski, Bull. W.H.O. 63:695-703, 1985; M. Mackett and L. C. Archard, J. Gen. Virol. 45:683-701, 1979], the possibility that monkeypox virus was a more remote ancestor of variola virus remained. We have now identified a sequence in monkeypox virus DNA which is a homolog of a 1,065-bp open reading frame in the conserved region of the variola virus genome but which has multiple deletions. This is strong evidence that monkeypox virus is not ancestral to variola virus and strengthens confidence in the long-term success of smallpox eradication.

Animals↗
PubMed1961

Susceptibility of suckling mice to variola virus.

Marshall, Ronald G. (Army Chemical Corps, Fredrick, Md.), and Peter J. Gerone. Susceptibility of suckling mice to variola virus. J. Bacteriol. 82:15-19. 1961.-The susceptibility of suckling mice inoculated intraperitoneally or intracerebrally with variola virus was investigated. Data are presented that define the death patterns, the relationship of incubation period to dose of virus inoculated, the multiplication of virus in suckling mice, and the influence of the age of suckling mice on their susceptibility to this virus. Additionally the results indicate that a variola virus neutralization test is feasible using the young suckling mouse as an indicator host.

Animals↗
PubMed2004

Protection against lethal vaccinia virus challenge in HLA-A2 transgenic mice by immunization with a single CD8+ T-cell peptide epitope of vaccinia and variola viruses.

CD8(+) T lymphocytes have been shown to be involved in controlling poxvirus infection, but no protective cytotoxic T-lymphocyte (CTL) epitopes are defined for variola virus, the causative agent of smallpox, or for vaccinia virus. Of several peptides in vaccinia virus predicted to bind HLA-A2.1, three, VETFsm(498-506), A26L(6-14), and HRP2(74-82), were found to bind HLA-A2.1. Splenocytes from HLA-A2.1 transgenic mice immunized with vaccinia virus responded only to HRP2(74-82) at 1 week and to all three epitopes by ex vivo enzyme-linked immunosorbent spot (ELISPOT) assay at 4 weeks postimmunization. To determine if these epitopes could elicit a protective CD8(+) T-cell response, we challenged peptide-immunized HLA-A2.1 transgenic mice intranasally with a lethal dose of the WR strain of vaccinia virus. HRP2(74-82) peptide-immunized mice recovered from infection, while naïve mice died. Depletion of CD8(+) T cells eliminated protection. Protection of HHD-2 mice, lacking mouse class I major histocompatibility complex molecules, implicates CTLs restricted by human HLA-A2.1 as mediators of protection. These results suggest that HRP2(74-82), which is shared between vaccinia and variola viruses, may be a CD8(+) T-cell epitope of vaccinia virus that will provide cross-protection against smallpox in HLA-A2.1-positive individuals, representing almost half the population.

Amino Acid Sequence↗
PubMed1976

Effect of temperature and relative humidity on variola virus in crusts.

The viability of variola virus in crusts under different conditions of temperature and relative humidity was studied for 16 weeks. At the ambient temperature of 25.8-26.4 degrees C and 85-90% relative humidity, the virus survived only 8 weeks but at lower temperatures and relative humidities the survival time was considerably prolonged.

Humans↗
PubMed1961

Replication of variola virus in suspended cultures of mammalian cells.

The studies reported here describe the successful propagation of variola virus in spinner cultures of mammalian cells, and the factors which influence its growth. Five established cell lines were used for the propagation of variola virus in a spinner culture system. Low doses of virus did initiate an infection but virus yields did not approach those obtained when an intermediate inoculum was used. Although the nonviable cell population remained low during the course of infection with an intermediate amount of virus, with an inoculum of 10(5) infectious units per ml or higher, the percentage of nonviable cells increased rapidly and by the sixth day after infection the population was totally nonviable. Intracellular replication of variola virus occurred early and rapidly in a spinner culture of guinea pig lung cells, whereas the liberation of virus into the suspending medium was a more gradual process. Several complete medium changes tend to maintain a suitable environment for the infected cell culture resulting in fairly high and constant viral titers over a period of 7 days.

Animals↗
PubMedDate not supplied

[Human recombinant antibodies to variola virus].

Eight specific antibodies to live variola virus (VV), Ind-3a strain, and 7 antibodies to VV, Butler strain, were selected from the synthetic combinatorial phage display library on single-chain (scFv) human antibodies. Indirect solid-phase enzyme immunoassay showed the ability of these antibodies to bind the VV strains Ind-3a, Butler, Brazil-131, Kuw-5, and Congo-2. Moreover, earlier selected human scFv antibodies were also tested in the reaction of binding to the above VV strains. The experiments could reveal the antibodies that bound alastrim strains more effectively that did other VV strains. The nucleotide sequences encoding for the selected scFv antibodies were determined.

Amino Acid Sequence↗
PubMed1993

Analysis of the nucleotide sequence of a 43 kbp segment of the genome of variola virus India-1967 strain.

Sequencing and computer analysis of the nucleotide sequence of the variola virus strain India-1967 (VAR) genome segment (43069 bp) from the region of HindIII C, E, R, Q, K, H DNA fragments has been carried out. Forty-three potential open reading frames (ORFs) have been identified, and the polypeptides encoded by them have been compared with the analogous proteins of vaccinia virus strain Copenhagen (COP). ORF E7R of VAR is much shorter than the COP analog. The other polypeptides coded by the potential ORFs of VAR are highly conserved in comparison with COP. Possible functions of the predicted viral polypeptides are discussed.

African Swine Fever Virus↗