Mason pfizer monkey virus
A Microbial Biorealm page on the genus Mason pfizer monkey virus
Classification
Higher order taxa
Viruses; Retro-transcribing viruses; Retroviridae; Orthoretrovirinae; Betaretrovirus NCBI
Species
Genus species: Mason Pfizer Monkey Virus
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NCBI: Taxonomy |
Description and significance
Mason Pfizer Monkey virus (MPMV)is a simian type-D retrovirus (SRV)and is the most thoroughly understood of the D-type betaretroviruses. MPMV is the prototype of the type-D retroviruses. The fundamental assembly steps(Gag particle formation, transport to the membrane, membrane interaction/viral budding, and viral release) are separate sequential processes allowing this virus to serve as an important model of retroviral assembly (Parker and Hunter, 2001). MPMV was first observed by Harish C. Chopra and Marcus M. Mason in 1970 from a spontaneous breast carcinoma in an 8-year old rhesus monkey (Macaca mulatta)(Chopra and Mason, 1970). MPMV is a primate retrovirus which has properties similar to the C-type and B-type viruses, but is morphologically distinct (Fine and Schochetman, 1978). MPMV is pathogenic in old world monkeys(Cercopithecidae)(Fine and Schochetman, 1978) causing immunodeficiency syndrome (Bohl et al., 2005) and tumors (Heras et al., 1991).
Genome structure
MPMV genome is dimeric; not segmented, and consists of a single molecule of linear, positive-sense single-stranded RNA. The genome has been fully sequenced and the complete genome is of one monomer of 8,557 nucleotides in length. The genome has terminally redundant sequences that have long terminal repeats (LTR) of about 350 nucleotides. The 5'–end of the genome has a methylated nucleotide cap; cap sequence type is of type 1 m7G5ppp5'GmpNp. The 3'–terminus has of each monomer a poly (A) tract. The 3'–terminus has a tRNA–like structure, and accepts lysin. http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/
Proteins constitute about 60% of the particle weight. The viral genome encodes structural proteins and non-structural proteins, with the non-structural proteins coding for an RNA-dependent DNA polymerase. http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/
The genome contains four protein coding genes, and two non protein coding genes. gag-pro-pol-env genes (MPMVgp1) code for protein products: Pr95, DU, RT-IN, gp70 SU, gp20 TM, and p12 PR. NC_001550. gag gene (MPMVgp2) codes for protein products: Pr78, p14 NC, p10 MA, p24, p12, and p 27. NC_001550. Non-protein coding genes are pro, (MPMVgp3) and pol, (MPMVgp4). NC_001550
Lipids are present and located in the envelope. The virions are composed of 35% lipids by weight. The composition of viral lipids and host cell membranes are similar. The lipids are of host origin and are derived from plasma membranes.http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/
Virion Structure
Two types of particles compose MPMV. A-type particles are intracytoplasmic,electron-dense, ring-shaped particles measuring about 70 m/u in diameter. These immature particles pre-assemble in the cytoplasm and may occur singly or in cluster (Mason, 1970). Fully formed immature particles subsequently migrate to the plasma membrane where envelopment and budding occur at the cell surface (Sakalian et al., 2002). Upon release, nascent immature particles undergo a maturation process to acquire infectivity (Bohl et al., 2005). These mature extracellular particles are composed of a well defined spherical oval membrane and a central dense nucleoid measuring about 110 m/n in diameter. The mature particles are connected to or very close the plasma membranes(Mason, 1970).
MPMV contains unique D-type morphology, similar yet distinguished morphology from type-C and type-B retrovirus. Less dense knob shaped surface spikes, and tubular nucleoid region.
Type D is also distinguished by accumulation of type A intracellular particles and budding release.
Virions{ }; have a complex construction; { } and consist of an envelope, a nucleocapsid, and a nucleoid. Virus capsid (core) is enveloped. Virions are spherical to pleomorphic; measure 80–100 nm in diameter. The surface projections are small { }; { } spikes { }; { } evenly covering the surface. They are { } densely dispersed. The core is spherical. The nucleoid is eccentric. http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/
Proteins constitute about 60% of the particle weight. The viral genome encodes structural proteins and non-structural proteins.
Non-Structural Proteins: The virus codes for an RNA-dependent DNA polymerase
Lipids are present; { } and are located in the envelope. Virions are composed of 35% lipids by weight. The composition of viral lipids and host cell membranes are similar. The lipids are of host origin; { }{ } are derived from plasma membranes. The virus contains intracellular ring-shaped, 60 to 95 nanometers in diameter A-type particles near the plasma membrane, as well as extracellular mature particles with an oval spherical outer unit membrane measuring 100 to 120 nanometers in diameter with an electron-dense sphere or a rod-shaped nucleoid 30 to 50 m/j in diameter. (Mason chopra)
the intracytoplasmic development and virus maturation by a process of budding at the level of the cell membrane
By itself, genomic nucleic acid is not infectious.
Translation: Replication involves a reverse transcription step.
Ecology
Habitat; symbiosis; contributions to the environment.
Mason Pfizer monkey virus was first isolated from mammary breast carcinoma in rhesus monkey, and old world monkey. Virus isolates maintain infectious in other old world monkeys such as langur monkeys, new world monkeys, as well as isolate type D retroviruses from humans; this retrovirus infects rhesus monkeys body temperature 36-40 degrees C Human 36.9. This slight fluctuation of temperature indicates this virus requires mesophillic conditions (15 and 40 °C)in a host.
Pathology
How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.
Requires host cells for metabolism Retroviral aspartyl protease. Single domain aspartyl proteases from retroviruses, retrotransposons, and badnaviruses (plant dsDNA viruses). These proteases are generally part of a larger polyprotein; usually pol, more rarely gag. Retroviral proteases appear to be homologous to a single domain of the two-domain eukaryotic aspartyl proteases such as pepsins, cathepsins, and renins (pfam00026)-Marchler-Bauer A, Anderson JB, Derbyshire MK, DeWeese-Scott C, Gonzales NR, Gwadz M, Hao L, He S, Hurwitz DI, Jackson JD, Ke Z, Krylov D, Lanczycki CJ, Liebert CA, Liu C, Lu F, Lu S, Marchler GH, Mullokandov M, Song JS, Thanki N, Yamashita RA, Yin JJ, Zhang D, Bryant SH. (2007) CDD: a conserved domain database for interactive domain family analysis. Nucleic Acids Res. 35: D237-40
RnaseH; RNase H. RNase H digests the RNA strand of an RNA/DNA hybrid. Important enzyme in retroviral replication cycle, and often found as a domain associated with reverse transcriptases. Structure is a mixed alpha+beta fold with three a/b/a layers. -Marchler-Bauer A, Anderson JB, Derbyshire MK, DeWeese-Scott C, Gonzales NR, Gwadz M, Hao L, He S, Hurwitz DI, Jackson JD, Ke Z, Krylov D, Lanczycki CJ, Liebert CA, Liu C, Lu F, Lu S, Marchler GH, Mullokandov M, Song JS, Thanki N, Yamashita RA, Yin JJ, Zhang D, Bryant SH. (2007) CDD: a conserved domain database for interactive domain family analysis. Nucleic Acids Res. 35: D237-40
Integrase Zinc binding domain. Integrase mediates integration of a DNA copy of the viral genome into the host chromosome. Integrase is composed of three domains. This domain is the amino-terminal domain zinc binding domain. The central domain is the catalytic domain pfam00665. The carboxyl terminal domain is a DNA binding domain pfam00552. PMID: 9228950 Induces fatal immune suppression by attacking T-lymphocyte cells in mammalian hosts. Newborns treated with MPMV - Older monkeys with MPMV-
Integrase DNA binding domain. Integrase mediates integration of a DNA copy of the viral genome into the host chromosome. Integrase is composed of three domains. The amino-terminal domain is a zinc binding domain. The central domain is the catalytic domain pfam00665. This domain is the carboxyl terminal domain that is a non-specific DNA binding domain. PMID: 7632683
Pr95 -
gp20 TM - ENV polyprotein (coat polyprotein). - Marchler-Bauer A, Anderson JB, Derbyshire MK, DeWeese-Scott C, Gonzales NR, Gwadz M, Hao L, He S, Hurwitz DI, Jackson JD, Ke Z, Krylov D, Lanczycki CJ, Liebert CA, Liu C, Lu F, Lu S, Marchler GH, Mullokandov M, Song JS, Thanki N, Yamashita RA, Yin JJ, Zhang D, Bryant SH. (2007) CDD: a conserved domain database for interactive domain family analysis. Nucleic Acids Res. 35: D237-40 - gag gene protein p24 (core nucleocapsid protein). p24 forms inner protein layer of the nucleocapsid. ELISA tests for p24 is the most commonly used method to demonstrate virus replication both in vivo and in vitro. PMID: 9245608
gp70 SU - ENV polyprotein (coat polyprotein)- Marchler-Bauer A, Anderson JB, Derbyshire MK, DeWeese-Scott C, Gonzales NR, Gwadz M, Hao L, He S, Hurwitz DI, Jackson JD, Ke Z, Krylov D, Lanczycki CJ, Liebert CA, Liu C, Lu F, Lu S, Marchler GH, Mullokandov M, Song JS, Thanki N, Yamashita RA, Yin JJ, Zhang D, Bryant SH. (2007) CDD: a conserved domain database for interactive domain family analysis. Nucleic Acids Res. 35: D237-40
Retroviral GAG p10 protein. This family consists of various retroviral GAG (core) polyproteins and encompasses the p10 region producing the p10 protein upon proteolytic cleavage of GAG by retroviral protease. The p10 or matrix protein (MA) is associated with the virus envelope glycoproteins in most mammalian retroviruses and may be involved in virus particle assembly, transport and budding. Some of the GAG polyproteins have alternate cleavage sites leading to the production of alternative and longer cleavage products (e.g. p19) the alignment of this family only covers the approximately N-terminal (GAG) 100 amino acid region of homology to p10. PMID: 9094640
Virus infects during its life cycle a single type of vertebrate host. Viral hosts belong to the Domain Eucarya.
Domain Eucarya Kingdom Animalia.
Kingdom Animalia Phylum Chordata.
Phylum Vertebrata Subphylum Vertebrata.
Class Mammalia.
Class Mammalia Order Primates. http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/
Isolate abundance in healthy rhesus monkeys
Symptoms
With direct hybridization of radioactive MPMV 70S RNA to DNA of various animal species, it has been shown that a portion (approximately 20%) of the MPMV genome was present in the cellular DNA of several Old World monkeys of the subfamily Cercopithecinae (34). No sequence homology was observed between MPMV and the cellular DNA's of New World monkeys, apes (including man), and several nonprimates (Fine and Schochetman, 1978).
RT-IN - RT_Rtv: Reverse transcriptases (RTs) from retroviruses (Rtvs). RTs catalyze the conversion of single-stranded RNA into double-stranded viral DNA for integration into host chromosomes. Proteins in this subfamily contain long terminal repeats (LTRs) and are multifunctional enzymes with RNA-directed DNA polymerase, DNA directed DNA polymerase, and ribonuclease hybrid (RNase H) activities. The viral RNA genome enters the cytoplasm as part of a nucleoprotein complex, and the process of reverse transcription generates in the cytoplasm forming a linear DNA duplex via an intricate series of steps. This duplex DNA is colinear with its RNA template, but contains terminal duplications known as LTRs that are not present in viral RNA. It has been proposed that two specialized template switches, known as strand-transfer reactions or "jumps", are required to generate the LTRs. PMID 9831551
Current Research
Enter summarries of the most rescent research here--at least three required
1) MPMV as a vector
2) Ancestral relations, origins
3)
References
Edited by student of Emily Lilly at University of Massachusetts Dartmouth.
