Vesicular Stomatitis Virus Particles Research Articles

Structure and origin of a novel class of defective interfering particle of vesicular stomatitis virus

The genome structure and terminal sequences of a 'copyback' defective interfering (DI) particle ST1, and a novel complexly rearranged 'snapback' DI particle ST2 of vesicular stomatitis virus have been determined. The ST1 DI genome RNA possesses 54 base long inverted complementary termini, the 5' end of which is homologous to the standard virus genome 5' end. Following this region of inverted complementarity the DI RNA 5' end continues to be homologous to standard virus RNA 5' sequences, whereas the 3' end diverges into sequences within the virus L gene internal sequences. ST2 DI genome RNA does not contain colinear covalently linked plus and minus sense RNA copies of the standard infectious virus RNA 5' terminus as predicted from the prototype snapback DI structure, but instead appears to be a hairpin copy of the ST1 DI RNA genome. This is the first evidence suggesting that DI particles may be generated from RNA templates other than the standard virus RNA. Generation models and the implications of these findings for RNA virus evolution are discussed.

The major ribonucleoprotein-associated protein kinase of vesicular stomatitis virus is a host cell protein.

Ribonucleoprotein particles (RNPs) of vesicular stomatitis virus (VSV) were fractionated by column chromatography through Fractogel TSK HW-55F and by centrifugation through KCl sucrose. Analyses of fractions for protein content and for protein kinase activity indicated that the major peak of kinase activity did not correspond exactly with any of the VSV-specific proteins. Neither anti-NS nor anti-M IgG preparations inhibited protein kinase activity, and IgG did not act as an exogenous phosphate acceptor. Reconstitution of an RNP-enzyme complex did not result in a restoration of protein kinase activity. In vitro translation of VSV-specific poly(A)-containing RNA did not result in any detectable production of kinase activity. Thus, the major RNP-associated kinase is a host cell protein which is tightly bound to the RNP particle.

Low infectivity of vesicular stomatitis virus (VSV) particles released from interferon-treated cells is related to glycoprotein deficiency

We have investigated the mechanism for the low infectivity of vesicular stomatitis virus (VSV) released from interferon (IFN) -treated cells. With 10–30 units/ml of IFN there was an approximately 5–30 fold reduction in the production of virus particles, as measured by VSV proteins; however, the infectivity of the VSV released from IFN-treated mouse L B, JLS-V9R, or human GM2504 was drastically reduced (2 to 4 logs). The low infectivity of VSV was directly related to a deficiency in virion glycoprotein (G). IFN treatment did not change the specific infectivity of the VSV particles released by HeLa cells; their G protein was also not reduced. A further effect of IFN to reduce the amount of virion M protein appeared to be secondary and was probably not related to the reduced infectivity of VSV.

Mechanism of interferon action: inhibition of vesicular stomatitis virus replication in human amnion U cells by cloned human leukocyte interferon. I. Effect on early and late stages of the viral multiplication cycle.

The kinetics of induction in human amnion U cells of the antiviral activity against vesicular stomatitis virus (VSV) produced by a single molecularly cloned subspecies of human leukocyte interferon (IFN-alpha A) were examined. IFN-alpha A-induced inhibition was found to be biphasic over a period of 24 h with the major extent of VSV inhibition occurring within the first 6 h of IFN treatment. The relationship of this major phase of inhibition to the early and late events of the VSV multiplication cycle was investigated. IFN-alpha A treatment had no detectable effect on the adsorption and penetration of VSV virions or on their uncoating to yield viral nucleocapsids. The polypeptides of adsorbed or uncoated VSV particles were neither preferentially degraded nor detectably altered in IFN-treated cells, as compared to untreated cells. Progeny virions released from IFN-treated cells, although greatly reduced in number, were found to be equally as infectious as those released from untreated cells. Progeny virions from IFN-treated cells also had a normal complement of VSV proteins in the same ratios as were seen in virions from untreated cells; specifically, IFN treatment produced no reduction in the incorporation of G or M protein into assembled virions. These results suggest that conditions of IFN treatment sufficient to reduce the yield of infectious VSV progeny greater than 99% do not detectably affect either the early or the late stages of the VSV multiplication cycle.

In vitro synthesis of genome length complementary RNA of vesicular stomatitis virus in the presence of inosine 5′-triphosphate

The virion-associated RNA polymerase of vesicular stomatitis virus (VSV) synthesizes RNA in vitro when GTP is replaced by inosine 5′-triphosphate (ITP). The synthesis is optimal at an ITP concentration of 200 μ M and the extent of synthesis is between 15 to 20% compared to normal transcription in the presence of GTP. Analyses of the RNA products revealed that approximately 10% of the product RNA represented plus-strand complement of the genome RNA. Defective interfering particles of VSV were also capable of synthesizing complementary RNA in the presence of ITP, in addition to 46-base RNA, although in lesser amount (2%). Since I substitution facilitates read-through of the genome RNA, these results suggest that interaction of the product RNA with the genome template or ITP-mediated modification of a viral protein may be involved in the readthrough process in vitro.

Generation and characterization of a non-defective interfering particle of vesicular stomatitis virus: homotypic and heterotypic interference.

SUMMARY Serial undiluted passages of vesicular stomatitis virus in African green monkey kidney (CV-1) cells resulted in the generation of a small-plaque-forming mutant. This mutant has been characterized as a non-defective particle with homotypic and heterotypic interference properties.

Cerulenin blocks fatty acid acylation of glycoproteins and inhibits vesicular stomatitis and Sindbis virus particle formation.

Cerulenin, an antibiotic that inhibits de novo fatty acid and cholesterol biosynthesis, effectively inhibited the formation and release of virus particles from chicken embryo fibroblasts infected with Sindbis or vesicular stomatitis virus (VSV). When added for 1 h at 3 h postinfection, the antibiotic blocked VSV particle production by 80 to 90% and inhibited incorporation of [3H]palmitic acid into the VSV glycoprotein by an equivalent amount. The effect of this antibiotic on virus protein and RNA biosynthesis was significantly less than that on fatty acid acylation. Nonacylated virus glycoproteins accumulated inside and on the surface of cerulenin-treated cells. These data indicate that fatty acid acylation is not essential for intracellular transport of these membrane proteins, but it may have an important role in the interaction of glycoproteins with membranes during virus assembly and budding.

Mediators of protection against lethal systemic vesicular stomatitis virus infection in hamsters: defective interfering particles, polyinosinate-polycytidylate, and interferon.

Homologous defective interfering (DI) particles protected adult Syrian hamsters against lethal systemic infection with vesicular stomatitis virus (VSV) serotype Indiana. The DI particles had to be biologically active, but did not have to be administered at the same inoculation site as the infectious virus. Serum and tissue levels of VSV postinoculation were significantly lower in DI-protected animals than in unprotected controls, suggesting that true autointerference was occurring. However, some aspects of protection also must be mediated through nonspecific mechanisms, since susceptible hamsters could be protected against VSV Indiana by coinjection with heterologous DI particles prepared from VSV serotype New Jersey or by simultaneous administration of polyinosinic acid-polycytidylic acid. By measuring serum levels of putative hamster interferon (type 1), we found that animals coinjected with VSV and DI particles or polyinosinic acid-polycytidylic acid produced significant levels of interferon. Since similarly high serum levels of interferon were measured in recipients of VSV alone (animals that eventually died from infection), there appeared to be no correlation between protection against lethal disease and induced levels of serum interferon. Instead, serum interferon levels correlated positively with amounts of VSV PFU found in serum and tissues of infected animals, the lowest levels being found in serum of animals protected with homologous DI particles. The data are consistent with the hypothesis that autointerference by DI particles as well as various host defense mechanisms (possibly including induction of interferon) participates in protecting hamsters against lethal VSV infection.

RNA polymerase-associated interactions near template promoter sequences of defective interfering particles of vesicular stomatitis virus.

Methylation protection studies suggested that the NS protein component of the RNA polymerase of vesicular stomatitis virus contacts the RNA templates of defective interfering (DI) particles at the sequence 3'...GUCUAUUUUUAUUUUUGGUG...5',17 to 37 nucleotides downstream from the site of initiation of in vitro transcription. The data indicated that vesicular stomatitis virus and DI particle RNAs contain different polymerase binding sequences and that NS may function as a transcription initiator protein for template recognition at both sequences. These results are thus compatible with the hypothesis that differences in the rate of defective and nondefective viral particle replication and autointerference are due to higher-affinity binding sites for polymerase at the 3' end of DI particle RNAs. In addition, a unique DI particle (DI-LT2) RNA that contains a transcriptionally inactive vesicular stomatitis virus leader gene 72 to 118 nucleotides from its 3' end showed interactions with the viral polymerase similar to those reported previously for the 3'-terminal vesicular stomatitis virus leader gene (Keene et al., Proc. Natl. Acad. Sci, U.S.A. 78:6191--6195, 1981). The interaction of polymerase with the internal leader gene of DI-LT2 RNA suggested that the lack of leader RNA and mRNA production by this particle is not due to the inability of polymerase to bind to internal sites along the template. Instead, the initiation of transcription is more likely influenced by the position of the polymerase binding site relative to the 3' end or by requisite interactions between the catalytic polymerase component (L) and the proposed initiator protein (NS).

Ultraviolet-irradiated vesicular stomatitis virus and defective-interfering particles are similar non-specific inhibitors of virus infection.

The way in which ultraviolet-irradiated vesicular stomatitis virus (VSV) inhibits the early events in VSV infection has been further characterized. Comparison of several different u.v.-irradiated thermolabile, temperature-sensitive mutants before and after heat inactivation established a requirement for inhibitory activity of functional G, N and L proteins, but not M protein. Defective-interfering (DI) particles, whether irradiated or not, inhibited VSV primary transcription as efficiently as UV-VSV, suggesting that virus proteins rather than transcription products are responsible for inhibition. Addition of inhibitory UV-VSV at different times after infection established that inhibition results from an action at an intracellular site, rather than at the cell surface or in the process of internalization. A similar inhibition by UV-VSV of infection by Sendai virus, Semliki Forest virus, Sindbis virus and influenza virus suggests that UV-VSV is acting by inducing a general change in the intracellular environment.

Replication of lactate dehydrogenase-elevating virus in macrophages. 2. Mechanism of persistent infection in mice and cell culture.

SUMMARY A primary infection of peritoneal macrophage cultures with the lactate dehydrogenase-elevating virus (LDV) results in productive infection of 3 to 20% of the cells. When cultures were incubated in the absence of macrophage growth factor (MGF), LDV production ceased after a single cycle, but in cultures in which macrophage replication was stimulated by the presence of MGF LDV production continued for several weeks at a low level, representing not more than 1% of that observed during the acute phase. Significant amounts of interferon were not present in either acutely or persistently infected cultures, and treatment of persistently infected cultures with anti-interferon globulin or superinfection with LDV did not significantly stimulate LDV replication. Macrophage cultures established with peritoneal macrophages from LDV-infected mice also showed only a low level of LDV replication and were resistant to superinfection by LDV. Mouse hepatitis virus, Semliki Forest virus and vesicular stomatitis virus, on the other hand, replicated normally in LDV-persistently infected macrophage cultures. LDV replication was relatively resistant to interferon whether added to the cultures or generated endogenously by infection with Newcastle disease virus or defective-interfering (DI) particles of vesicular stomatitis virus. Temperature-sensitive mutants or DI particles of LDV were not detected in LDV-persistently infected cultures or chronically infected mice. The results support our hypothesis that the decrease in LDV production in mice or macrophage cultures at the end of the acute phase results from the destruction of the subpopulation of macrophages that is permissive for LDV, and that the low level persistent infection involves the passage of the virus to new permissive cells that are generated continuously, although at a low rate, from non-permissive precursor cells.

Interference among defective interfering particles of vesicular stomatitis virus.

Three defective interfering (DI) particles of vesicular stomatitis virus (VSV), all derived from the same parental standard San Juan strain (Indiana serotype), were used in various combinations to infect cells together with the parental virus. The replication of their RNA genomes in the presence of other competing genomes was described by the hierarchical sequence: DI 0.52 particles greater than DI 0.45 particles less than or equal to DI-T particles greater than standard VSV. The advantage of one DI particle over another was not due simply to multiplicity effects nor to the irreversible occupation of limited cellular sites. Interference, however, did correlate with a change in the ratio of plus and minus RNA templates that accumulated intracellularly and with the presence of new sequences at the 3' end of the DI genomes. DI 0.52 particles contained significantly more nucleotides at the 3' end that were complementary to those at the 5' end of its RNA than did DI-T or DI 0.45 particles. The first 45 nucleotides at the 3' ends of all of the DI RNAs were identical. VSV and its DI particles can be separated into three classes, depending on their terminal RNA sequences. These sequences suggest two mechanisms, one based on the affinity of polymerase binding and the other on the affinity of N-protein binding, that may account for interference by DI particles against standard VSV and among DI particles themselves.

Suppression of vesicular stomatitis virus defective intefering particle generation by a function(s) associated with human chromosome 16.

Human-mouse somatic cell hybrids were made between adenine phosphoribosyltransferase-deficient mouse L cells and a strain of human primary fibroblasts and selected in medium containing alanosine and adenine (J. A. Tischfield and F. H. Ruddle, Proc. Natl. Acad. Sci. U.S.A. 71:45-49, 1974). These hybrids were tested for the generation of defective interfering (DI) particles of vesicular stomatitis virus to determine whether or not a host gene controls the induction of DI particles. None of the seven independently arising hybrid clones tested generated detectable DI particles during 13 successive undiluted passages. In addition, the parental human cells also failed to generate DI particles. In contrast, the parental mouse cells generated a detectable level of DI particles during continuous passage. Thus, failure to generate DI particles appears to act in a dominant fashion in these hybrids. Human chromosome 16 and adenine phosphoribosyltransferase were present, as a direct consequence of the selection system, in all of the hybrid clones that failed to generate DI particles. It was the only human chromosome observed in the cells of every hybrid clone. This was verified by both isozyme and karyotype analyses. After hybrids were back-selected (with 2,6-diaminopurine) for loss of human adenine phosphoribosyltransferase and chromosome 16, they gained the ability to generate DI particles. Replication of DI particles already present in virus stocks, however, was normal in all of the hybrid clones and the parental human cells. This suggests that the induction, but not the replication, of DI particles is affected by the human genome and that a factor on human chromosome 16 seems to selectively suppress the mouse cell's ability to generate DI particles in the hybrids. These results support the idea that the induction of DI particles is controlled in part by host cell function(s), as suggested previously (C. Y. Kang and R. Allen, J. Virol. 25:202-206, 1978).

Delayed appearance of pseudotypes between vesicular stomatitis virus influenza virus during mixed infection of MDCK cells

In intact Madin-Darby canine kidney (MDCK) cell monolayers, vesicular stomatitis virus (VSV) matures only at basolateral membranes beneath tight junctions, whereas influenza virus buds from apical cell surfaces. Early in the growth cycle, the viral glycoproteins are restricted to the membrane domain from which each virus buds. We report here that phenotypic mixing and formation of VSV pseudotypes occurred when influenza virus-infected MDCK cells were superinfected with VSV. Up to 75% of the infectious VSV particles from such experiments were neutralized by antiserum specific for influenza virus, and a smaller proportion (up to 3%) were resistant to neutralization with antiserum specific for VSV. The latter particles, which were neutralized by antiserum to influenza A/WSN virus, are designated as VSV(WSN) pseudotypes. During mixed infections, both wild-type viruses were detected 1 to 2 h before either phenotypically mixed VSV or VSV(WSN) pseudotypes. Coincident with the appearance of cytopathic effects in the monolayer, the yield of pseudotypes rose dramatically. In contrast, in doubly infected BHK-21 cells, which do not show polarity in virus maturation sites and are not connected by tight junctions, VSV(WSN) pseudotypes were detected as soon as VSV titers rose to the minimum levels which allowed detection of pseudotypes, and the proportion observed remained relatively constant at later times. Examination of thin sections of doubly infected MDCK monolayers revealed that polarity in maturation sites was preserved for both viruses until approximately 12 h after inoculation with influenza virus, when disruption of junctional complexes was evident. Even at later periods, the majority of each virus type was associated with its normal membrane domain, suggesting that the sorting mechanisms responsible for directing the glycoproteins of VSV and influenza virus to separate surface domains continue to operate in doubly infected MDCK cells. The time course of VSV(WSN) pseudotype formation and changes in virus maturation sites are compatible with progressive mixing of viral glycoproteins at either intracellular or plasma membranes of doubly infected cells.

Lipid-protein interactions between the surface glycoprotein of vesicular stomatitis virus and the lipid bilayer

Spin label electron spin resonance (ESR) techniques were used to detect changes in lipid bilayer structure caused by the addition of the envelope surface glycoprotein (G protein) of vesicular stomatitis virus (VSV) to phospholipid vesicles. G protein was extracted from intact VSV particles by solubilizing the virus envelope with lysolecithin. The extracted protein was added to sonicated egg yolk phosphatidylcholine (PC) vesicles and the detergent was removed with bovine serum albumin. The G protein to lipid ratio of the reconstituted vesicles was similar to that of the intact virus envelope and the reconstituted vesicles caused hemagglutination of the goose erythrocytes and bound to BHK cells. ESR spectra of a nitroxide-labeled stearic acid spin label incorporated into the lipid bilayer of the reconstituted vesicles indicated that the addition of G protein to PC vesicles increased the rigidity of the vesicle lipid bilayer suggesting that the hydrophobic terminus of the VSV G protein may alter the lipid bilayer structure. Addition of anti-G IgG to reconstituted vesicles caused a further increase in bilayer rigidity suggesting that cross-linking of membrane proteins may alter lipid bilayer structure.

Structural changes in BHK cell plasma membrane caused by the binding of vesicular stomatitis virus

Spin label electron spin resonance techniques using a nitroxide derivative of stearic acid were used to detect changes in plasma membrane structure caused by the binding of vesicular stomatitis virus (VSV) to cell plasma membranes of intact BHK-21 cells. The results indicate that binding of VSV to cell surface receptors causes an increase in the observed rigidity of the plasma membrane lipid bilayer. This change in membrane structure, which appears to be caused by the cross-linking of receptors in the plane of the plasma membrane, could be prevented by treating the cells with colchicine before addition of virus and could be reversed by treating the cells with colchicine after addition of virus. Cells treated with a monovalent, water-soluble derivative of VSV G-protein (Gs) did not show an increase in plasma membrane bilayer rigidity. However, addition of anti-VSV G-protein immunoglobulin G to cells pretreated with G8 caused an increase in plasma membrane bilayer rigidity. This increased rigidity could also be reversed by the addition of colchicine. Fluorescence microscopy was used to determine the distribution of fluorescein-labeled VSV particles on the cell surface after addition of virus. Approximately 30 min after addition of virus, discrete areas on the cell surface showed fluorescent staining, which coalesced to apical regions of the cell after approximately 40 min.

Differential effect of monensin on enveloped viruses that form at distinct plasma membrane domains.

We have observed a striking differential effect of the ionophore, monensin, on replication of influenza virus and vesicular stomatitis virus (VSV) in Madin-Darby canine kidney (MDCK) and baby hamster kidney (BHK21) cells. In MDCK cells, influenza virus is assembled at the apical surfaces, whereas VSV particles bud from the basolateral membranes; no such polarity of maturation is exhibited in BHK21 cells. A 10(-6) M concentration of monensin reduces VSV yields in MDCK cells by greater than 90% as compared with controls, whereas influenza virus yields are unaffected. In BHK21 cells, monensin also inhibits VSV production, but influenza virus is also sensitive to the ionophore. Immunofluorescent staining of fixed and unfixed MDCK monolayers indicates that VSV glycoproteins are synthesized in the presence of monensin, but their appearance on the plasma membrane is blocked. Electron micrographs of VSV-infected MDCK cells treated with monensin show VSV particles aggregated within dilated cytoplasmic vesicles. Monensin-treated influenza virus-infected MDCK cells also contain dilated cytoplasmic vesicles, but virus particles were not found in these structures, and numerous influenza virions were observed budding at the cell surface. These results indicate that influenza virus glycoprotein transport is not blocked by monensin treatment, whereas there is a block in transport of VSV G protein. Thus it appears that at least two distinct pathways of transport of glycoproteins to the plasma membrane exist in MDCK cells, and only one of them is blocked by monensin.

Chapter 2 Synthesis and Assembly of Transmembrane Viral and Cellular Glycoproteins

Publisher Summary This chapter discusses the synthesis and assembly of transmembrane viral and cellular glycoproteins, including transmembrane biosynthesis of the vesicular stomatitis virus (VSV) glyco (G) protein. VSV encodes five polypeptides, all of which are structural components of the virions, and directs the synthesis of five corresponding messenger ribonucleic acid (mRNA) species. A VSV particle, like those of most lipid-containing animal viruses, is formed by budding from the plasma membrane of an infected cell. The chapter discusses the biogenesis of two sindbis virus G proteins. Sindbis, like VSV, is a lipid-enveloped virus; however, it contains only three structural proteins, two of which are envelope G proteins—that is, integral membrane proteins (E 1 and E 2 ). The interaction of nascent Sindbis glycoprotein and the endoplasmic reticulum and the movement of transmembrane viral glycoproteins from the rough endoplasmic reticulum to the plasma membrane are described in the chapter.

Generation of defective interfering particles of vesicular stomatitis virus in Aedes albopictus cells

The serial undiluted passage of clonally purified vesicular stomatitis virus (VSV) in Aedes albopictus cells resulted in a rapidly declining titer of infectious virus. VSV AP2 (a stock derived after two such passages) contained slowly sedimenting truncated (T) particles which were interfering and noninfectious. Whereas a VSV stock produced by three undiluted passages in BHK cells (VSV BP3) interfered with the replication of standard virus (VSV STD) equally well in A. albopictus and in BHK cells, VSV AP2 interfered efficiently only in the former. These patterns of interference were also observed when gradient purified T particles were tested. When VSV AP2 or VSV BP3 was passaged once in the heterologous cell type the pattern of interference was reversed showing that these defective interfering (DI) particles could be phenotypically modified in such a way as to influence their specificity of interference with VSV STD. When viral RNA synthesis was studied in cells coinfected with VSV STD and VSV AP2 or VSV BP3, the following observations were made: (1) interference was correlated with a decrease in the synthesis of 42 S VSV STD genome RNA; (2) although VSV AP2 DI particles interfered well in A. albopictus cells but only poorly in BHK cells the DI RNA genomes of VSV AP2 were replicated equally well in both cell types. (3) The major DI particles in VSV AP2 contained “snap-back” RNA composed of covalently linked sequences of positive and negative polarity. By testing the effect of RNase on these RNAs it was concluded that they contained from 90 to 95% selfcomplementary sequences. Snap-back RNA was not readily detectable in the DI particles of VSV BP3.

Defective interfering particles of vesicular stomatitis virus: structure-function relationships.

Annals of the New York Academy of SciencesVolume 354, Issue 1 p. 238-250 DEFECTIVE INTERFERING PARTICLES OF VESICULAR STOMATITIS VIRUS: STRUCTURE-FUNCTION RELATIONSHIPS* Alice S. Huang, Alice S. Huang Division of Infectious Diseases Children's Hospital Medical Center Boston, Massachusetts 02115 and Department of Microbiology and Molecular Genetics Harvard Medical School Boston, Massachusetts 02115Search for more papers by this authorDonald D. Rao, Donald D. Rao Division of Infectious Diseases Children's Hospital Medical Center Boston, Massachusetts 02115 and Department of Microbiology and Molecular Genetics Harvard Medical School Boston, Massachusetts 02115Search for more papers by this authorGertrude Lanman, Gertrude Lanman Division of Infectious Diseases Children's Hospital Medical Center Boston, Massachusetts 02115 and Department of Microbiology and Molecular Genetics Harvard Medical School Boston, Massachusetts 02115Search for more papers by this author Alice S. Huang, Alice S. Huang Division of Infectious Diseases Children's Hospital Medical Center Boston, Massachusetts 02115 and Department of Microbiology and Molecular Genetics Harvard Medical School Boston, Massachusetts 02115Search for more papers by this authorDonald D. Rao, Donald D. Rao Division of Infectious Diseases Children's Hospital Medical Center Boston, Massachusetts 02115 and Department of Microbiology and Molecular Genetics Harvard Medical School Boston, Massachusetts 02115Search for more papers by this authorGertrude Lanman, Gertrude Lanman Division of Infectious Diseases Children's Hospital Medical Center Boston, Massachusetts 02115 and Department of Microbiology and Molecular Genetics Harvard Medical School Boston, Massachusetts 02115Search for more papers by this author First published: November 1980 https://doi.org/10.1111/j.1749-6632.1980.tb27970.xCitations: 6 * Supported by the National Institutes of Health (Grant AI 16625) and the American Cancer Society (Grant VC-63). AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume354, Issue1Genetic Variation of VirusesNovember 1980Pages 238-250 RelatedInformation