Superinfection exclusion of vaccinia virus in virus-infected cell cultures

Superinfection exclusion is a widespread phenomenon that prevents secondary infections by closely related viruses. The vaccinia virus A56 and K2 proteins in the cell membrane can prevent superinfection by interacting with the entry-fusion complex of subsequent viruses. Here, we described another form of exclusion that is established earlier in infection and does not require the A56 or K2 protein. Cells infected with one or more infectious virions excluded hundreds of superinfecting vaccinia virus particles. A related orthopoxvirus, but neither a flavivirus nor a rhabdovirus, was also excluded, indicating selectivity. Although superinfecting vaccinia virus bound to cells, infection was inhibited at the membrane fusion step, thereby preventing core entry into the cytoplasm and early gene expression. In contrast, A56/K2 protein-mediated exclusion occurred subsequent to membrane fusion. Induction of resistance to superinfection depended on viral RNA and protein synthesis by the primary virus but did not require DNA replication. Although superinfection resistance correlated with virus-induced changes in the cytoskeleton, studies with mutant vaccinia viruses indicated that the cytoskeletal changes were not necessary for resistance to superinfection. Interferon-inducible transmembrane proteins, which can inhibit membrane fusion in other viral systems, did not prevent vaccinia virus membrane fusion, suggesting that these interferon-inducible proteins are not involved in superinfection exclusion. While the mechanism remains to be determined, the early establishment of superinfection exclusion may provide a "winnertake-all" reward to the first poxvirus particles that successfully initiate infection and prevent the entry and genome reproduction of defective or less fit particles. IMPORTANCEThe replication of a virus usually follows a defined sequence of events: attachment, entry into the cytoplasm or nucleus, gene expression, genome replication, assembly of infectious particles, and spread to other cells. Although multiple virus particles may enter a cell at the same time, mechanisms exist to prevent infection by subsequent viruses. The latter phenomenon, known as superinfection exclusion, can occur by a variety of mechanisms that are not well understood. We showed that superinfection by vaccinia virus was prevented at the membrane fusion step, which closely followed virion attachment. Thus, neither gene expression nor genome replication of the superinfecting virus occurred. Expression of early proteins by the primary virus was necessary and sufficient to induce the superinfection-resistant state. Superinfection exclusion may be beneficial to vaccinia virus by selecting particles that can infect cells rapidly, excluding defective particles and synchronizing the replication cycle.T he ability of an established virus infection to interfere with a secondary infection by a homologous virus was first described in bacteriophages and subsequently in animal and plant viruses with RNA and DNA genomes (1). The wide occurrenc...

mentioning

confidence: 92%

A Novel Mode of Poxvirus Superinfection Exclusion That Prevents Fusion of the Lipid Bilayers of Viral and Cellular Membranes

Laliberte

Moss

2014

“…Twelve plantlets were agroinoculated with a 1/1 ratio of the two genotypes on the 2nd and 3rd leaves. mRFP1 and mGFP5 fluorescence levels in leaf level 7 (the second systemically infected leaf level) were scanned 10 times in 15 days (at days 7,8,9,10,11,15,17,18,21, and 22 after appearance on the plant) in all of the plants. Analyses of the same leaves along a time course was possible because the plants had been potted in containers, allowing us to place plants in a Typhoon FLA 9000 scanner (GE Healthcare Life Sciences) and to scan the fluorescence of uncut leaves.…”

Section: Methodsmentioning

confidence: 99%

“…It is remarkable that many unrelated viruses can prevent secondary infections of cells by closely related genotypes (9)(10)(11)(12)(13)(14)(15)(16)(17)(18). In these cases of "superinfection exclusion," different viral genotypes coinfecting a host are rarely found coinfecting cells, and they sometimes segregate into distinct groups of cells or tissues within which only one genotype is observed (19)(20)(21)(22)(23)(24)(25).…”

Section: Importancementioning

confidence: 99%

The Multiplicity of Cellular Infection Changes Depending on the Route of Cell Infection in a Plant Virus

Gutiérrez

Pirolles

Yvon

et al. 2015

The multiplicity of cellular infection (MOI) is the number of virus genomes of a given virus species that infect individual cells. This parameter chiefly impacts the severity of within-host population bottlenecks as well as the intensity of genetic exchange, competition, and complementation among viral genotypes. Only a few formal estimations of the MOI currently are available, and most theoretical reports have considered this parameter as constant within the infected host. Nevertheless, the colonization of a multicellular host is a complex process during which the MOI may dramatically change in different organs and at different stages of the infection. IMPORTANCEThe MOI is the size of the viral population colonizing cells and defines major phenomena in virus evolution, like the intensity of genetic exchange and the size of within-host population bottlenecks. However, few studies have quantified the MOI, and most consider this parameter as constant during infection. Our results reveal that the MOI can depend largely on the route of cell infection in a systemically infected leaf. The MOI is usually one genome per cell when cells are infected from virus particles moving long distances in the vasculature, whereas it is much higher during subsequent cell-to-cell movement in mesophyll. However, a fast-acting superinfection exclusion prevents cell coinfection by merging populations originating from different primary foci within a leaf. This complex colonization pattern results in a situation where within-cell interactions are occurring almost exclusively among kin and explains the common but uncharacterized phenomenon of genotype spatial segregation in infected plants.V iral populations can evolve rapidly, even during a single host infection, and the resulting changes in the population ultimately can affect the outcome of viral diseases. A clear example of this is the emergence of drug-resistant mutants of animal/human viruses, of resistance-breaking variants of plant viruses, or of recombinant genotypes with an enlarged host range. Therefore, it is not surprising that increasing efforts are being made to characterize parameters defining within-host evolution of viral populations.Since viruses are obligate intracellular parasites, a fundamental parameter determining their within-host population dynamics/ genetics is the multiplicity of cellular infection (MOI), defined as the number of genomes of a given virus species that infects a cell. The MOI influences two major processes in viral evolution, namely, the population bottlenecks and the interactions among genotypes. Within-host bottlenecks are linked to the number of infected cells during host colonization and to the MOI at which these cells are infected. The overall intensity of interactions among viral genomes, i.e., competition, genetic exchange, functional complementation, and collective action, depends to a large extent on the probability of encountering different genotypes within host cells, a probability that is directly linked to the MOI. Given the ...

“…Superinfection exclusion is observed during infections by a broad range of viruses, including human immunodeficiency virus (HIV) (17), vesicular stomatitis virus (VSV) (38), vaccinia virus (5), and alphavirus (14). There is some evidence to suggest that superinfection exclusion occurs in hepadnavirus infections as well.…”

mentioning

confidence: 99%

Superinfection Exclusion in Duck Hepatitis B Virus Infection Is Mediated by the Large Surface Antigen

Walters

Joyce

Addison

et al. 2004

Superinfection exclusion is the phenomenon whereby a virus prevents the subsequent infection of an already infected host cell. The Pekin duck hepatitis B virus (DHBV) model was used to investigate superinfection exclusion in hepadnavirus infections. Superinfection exclusion was shown to occur both in vivo and in vitro with a genetically marked DHBV, DHBV-ClaI, which was unable to establish an infection in either DHBVinfected ducklings or DHBV-infected primary duck hepatocytes (PDHs). In addition, exclusion occurred in vivo even when the second virus had a replicative advantage. Superinfection exclusion appears to be restricted to DHBV, as adenovirus, herpes simplex virus type 1, and vesicular stomatitis virus were all capable of efficiently infecting DHBV-infected PDHs. Exclusion was dependent on gene expression by the original infecting virus, since UV-irradiated DHBV was unable to mediate the exclusion of DHBV-ClaI. Using recombinant adenoviruses expressing DHBV proteins, we determined that the large surface antigen mediated exclusion. The large surface antigen is known to cause down-regulation of a DHBV receptor, carboxypeptidase D (CPD). Receptor down-regulation is a mechanism of superinfection exclusion seen in other viral infections, and so it was investigated as a possible mechanism of DHBV-mediated exclusion. However, a mutant large surface antigen which did not down-regulate CPD was still capable of inhibiting DHBV infection of PDHs. In addition, exclusion of DHBV-ClaI did not correlate with a decrease in CPD levels. Finally, virus binding assays and confocal microscopy analysis of infected PDHs indicated that the block in infection occurs after internalization of the second virus. We suggest that superinfection exclusion may result from the role of the L surface antigen as a regulator of intracellular trafficking.Hepadnaviruses are a family of enveloped, hepatotropic viruses with small (3.0-to 3.2-kb), partially double-stranded DNA genomes (28). The family includes viruses infecting the woodchuck, ground squirrel, grey heron, snow goose, and Pekin duck (duck hepatitis B virus [DHBV]) as well as the medically important human hepatitis B virus (HBV).The virion is an icosahedral capsid made up of a core protein surrounded by a lipid bilayer that contains the viral envelope proteins. Contained within the capsid is the viral genome with the polymerase protein covalently attached to the 5Ј terminus of the minus strand. The hepadnavirus genome is organized into overlapping reading frames that encode the precore, core, polymerase, and surface proteins. The mammalian hepadnaviruses, as well as the majority of the avian hepadnaviruses, contain an additional open reading frame that encodes the X protein (10). Infection is initiated by the interaction of the virus with a receptor present on the surface of hepatocytes. Carboxypeptidase D (CPD) has been identified as a receptor for DHBV, although it appears that additional coreceptors are required (4,7,35). Following attachment, the virus enters the cell, likely by ...