Raccoonpox virus
Raccoonpox virus | |
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Virus classification | |
(unranked): | Virus |
Realm: | Varidnaviria |
Kingdom: | Bamfordvirae |
Phylum: | Nucleocytoviricota |
Class: | Pokkesviricetes |
Order: | Chitovirales |
Family: | Poxviridae |
Genus: | Orthopoxvirus |
Species: | Raccoonpox virus
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Raccoonpox virus (RCN) is a double-stranded
Of the 92 apparently healthy raccoons trapped near Aberdeen, Maryland in 1961, 22 had sera containing RCN HA1 antibodies. The sera partially cross-reacted with a
Viral classification
RCN is a double-stranded DNA virus. It is an orthopoxvirus in the family Poxviridae and subfamily Chordopoxvirinae.
Genealogy/ evolution
DNA sequences encoding the HA's of RCN and VV (
In contrast to known members of the poxvirus group, RCN is serologically (diagnostic identification of antibodies in
Structure
RCN is an
Differences between terminal region patterns of DNA restriction enzyme digests of different RCN isolates suggest that varied passaging has promoted the advancement of polymorphisms since the virus was first isolated in 1961.[6] RCN tandem repeat sequences found on the terminal Sal1 restriction fragment were found to be distinct from varicella and cowpox virus, lending further support to the claim that RCN is a distinct virus within the orthopoxviruses.[6] In order to distinguish between the orthopoxvirus species and strains of RCN, PCR is used. The distinction is drawn based on the sequences encoding the hemagglutinin (HA) protein.[3]
Genome replication cycle
Entry into Cell: The virion attaches to the cell surface as the viral proteins come into contact with host cell glycosaminoglycan receptors and is taken into the cell through endocytosis. From here it must enter into the cytoplasm. The replication of RCN occurs in the cytoplasm- never in the nucleus.[1]
Replication and Transcription: The replication and transcription of the viral genome occur in the cytoplasm. Genome replication begins with the uncoating of the virus core as it comes into contact with the plasma membrane. Once uncoated, the viral DNA is expressed and replication follows.[1] Replication of the RCN genome occurs through the strand displacement method.
Assembly and Release: Viral assembly occurs in the cytoplasm. The release of the mature virus particle always results in lysing of the host cell.[1]
Modulation of host processes
RCN has a negative effect on the
Identification
RCN isolated from 2 of 92 raccoons in Maryland, proposed to be an orthopoxvirus when it was noted that a RCN hemagglutinin preparation reacted with VV (vaccinia virus) hyperimmune rabbit serum. However, it was later reported that sera from 22 of the raccoons reacted highly with a RCN hemagglutinin preparation, but hemagglutinin preparations of VV or monkeypox virus (MPV) showed little or no cross-reactivity.[4]
Identify via agglutination with
Associated disease
RCN infected Strain 143 human osteosarcoma cells produce cytoplasmic A-type inclusions (ATIs) where a number of mature virions are lodged to maintain viral infectivity even if the cell lyses.[7]
Pathogenesis
Cell lines infected with RCN, volepox virus (VPX), or skunk poxvirus (SKP), and other orthopoxviruses that are all HAD+ (hemagglutinating viruses based on adherence to erythrocytes to infected cells), form large syncytia (multinucleated cells that can result from the fusion of uninuclear cells), suggest that, conformationally, distinct functional HA's influence polykaryocytosis (process of fusion).[4]
RCN has cytopathic effects (CPE) in monkey kidney tissue cultures (MKTC). Seen on 11h day of incubation, characterized by rounding and granular appearance of cells.[2] When inoculated on the chorioallantoic membrane (CAM) of 12-day embryonated hens’ eggs, the RCN produced many small discrete embedded poxes.[2]
Tropism
Raccoon poxvirus has been shown to infect Strain 143 human osteosarcoma cells grown in monolayer culture, producing A-type inclusions in the cytoplasm as is typical of poxviruses in later multiplication cycles.[8]
To date, most oral vaccines cannot withstand the alimentary tract or do not elicit strong mucosal immune response. Poxviruses are good candidates for the development of wildlife vaccines. They infect mucosal tissue and retain stability when disrupted by the environment.[9]
Use
RCN has been developed as a recombinant for the delivery of vaccines against the
RCN is favored as a vector for wildlife and
RCN, and all poxviridae viruses, are especially useful in creating vaccines because they create cost-effective, stable, multivalent vaccines that are easy to manufacture, and can be administered through multiple routes.[1] It is believed that RCN vaccination triggers action from both the humoral and cell mediated immune responses and that this immunity is long term after only one vaccination.[1]
Poxvirus recombinant vectors have been implemented to successfully vaccinate against heterologous bacterial, viral, and parasitic pathogens upon use in animals (e.g. raccoons) and humans.[13]
Uses in veterinary medicine: have potential use for this treatment technique in infectious disease, ex vivo therapies, and cancer immunotherapy. *Under clinical trials as well as some licensed commercialization at time of publication.[13]
RCN viral vectors have the potential to replace expensive and labor-intensive pesticide applications in disease prevention.[14]
Recombinant RCN vaccine promote effective immunity against plague (Y. pestis) via the oral route, could provide a practical, alternative approach, although more work is needed to determine the timing of vaccine, the duration of immunity provided, and the effects on nontarget animals.[14]
RCN recombinants expressing rabies virus glycoprotein or nucleoprotein were created. Promoting rabies virus neutralizing antibodies in raccoons, dogs, cotton rats, rabbits, bobcats, and foxes; sometimes at lethal doses.[15]
RCN is used as an oral delivery system for fraction 1 (F1) capsular antigen of Y.pestis. (replacement of thymidine kinase (TK)). RCN was successful in 50% of voluntary participants allowing them to survive subsequent challenges. RCN-vectored vaccine with the LcrV (V) gene, which can also provide protection against Y. pestis.[9]
References
- ^ a b c d e f g h i Pastoret, P. P., & Vanderplasschen, A. (2003). Poxviruses as vaccine vectors [Electronic version]. Comparative Immunology, Microbiology, and Infectious Diseases, 26, 343-355.
- ^ PMID 4336527.
- ^ PMID 1529542.
- ^ PMID 19879228.
- ^ "Orthopoxvirus". ViralZone. Retrieved 12 December 2015.
- ^ PMID 7559950.
- PMID 1529541.
- PMID 22438543.
- ^ PMID 20158332.
- ^ PMID 12559803.
- ^ PMID 2033678.
- ^ S2CID 19453576.
- ^ PMID 8876138.
- ^ PMID 3456179.
- S2CID 30909913.