Editing Rotavirus (section)

==== Structural proteins ====
[[File:Rotavirus with gold- labelled monoclonal antibody.jpg|thumb|Electron micrograph of gold nanoparticles attached to rotavirus. The small dark circular objects are gold nanoparticles coated with a [[monoclonal antibody]] specific for rotavirus protein VP6.|alt=An electron micrograph of many rotavirus particles, two of which have several smaller, black spheres which appear to be attached to them|left]]VP1 is located in the core of the virus particle and is an [[RNA-dependent RNA polymerase]] [[enzyme]].<ref name="pmid17657346">{{cite journal |vauthors=Vásquez-del Carpió R, Morales JL, Barro M, Ricardo A, Spencer E |title=Bioinformatic prediction of polymerase elements in the rotavirus VP1 protein |journal=Biological Research |volume=39 |issue=4 |pages=649–659 |year=2006 |pmid=17657346 |doi=10.4067/S0716-97602006000500008 |doi-access=free }}</ref> In an infected cell this enzyme produces mRNA transcripts for the synthesis of viral proteins and produces copies of the rotavirus genome RNA segments for newly produced virus particles.<ref name="pmid22595300">{{cite journal |vauthors=Trask SD, Ogden KM, Patton JT |title=Interactions among capsid proteins orchestrate rotavirus particle functions |journal=Current Opinion in Virology |volume=2 |issue=4 |pages=373–379 |year=2012 |pmid=22595300 |pmc=3422376 |doi=10.1016/j.coviro.2012.04.005 }}</ref>

VP2 forms the core layer of the virion and binds the RNA genome.<ref name="pmid15010217">{{cite journal |vauthors=Taraporewala ZF, Patton JT |title=Nonstructural proteins involved in genome packaging and replication of rotaviruses and other members of the Reoviridae |journal=Virus Research |volume=101 |issue=1 |pages=57–66 |year=2004 |pmid=15010217 |doi=10.1016/j.virusres.2003.12.006 |url=https://zenodo.org/record/1259439}}</ref>

VP3 is part of the inner core of the virion and is an enzyme called [[guanylyl transferase]]. This is a [[capping enzyme]] that catalyses the formation of the [[5' cap]] in the [[post-transcriptional modification]] of mRNA.<ref name="isbn0-12-375147-02">{{cite book |vauthors=Angel J, Franco MA, Greenberg HB |veditors=Mahy BW, Van Regenmortel MH |title=Desk Encyclopedia of Human and Medical Virology |publisher=Academic Press |location=Boston |year=2009 |page=277 |isbn=978-0-12-375147-8}}</ref> The cap stabilises viral mRNA by protecting it from [[nucleic acid]] degrading enzymes called [[nucleases]].<ref name="pmid20025612">{{cite journal |vauthors=Cowling VH |title=Regulation of mRNA cap methylation |journal=The Biochemical Journal |volume=425 |issue=2 |pages=295–302 |year=2009 |pmid=20025612 |pmc=2825737 |doi=10.1042/BJ20091352 }}</ref>

VP4 is on the surface of the virion that protrudes as a spike.<ref name="pmid16571811">{{cite journal |vauthors=Gardet A, Breton M, Fontanges P, Trugnan G, Chwetzoff S |title=Rotavirus spike protein VP4 binds to and remodels actin bundles of the epithelial brush border into actin bodies |journal=Journal of Virology |volume=80 |issue=8 |pages=3947–3456 |year=2006 |pmid=16571811 |doi=10.1128/JVI.80.8.3947-3956.2006 |pmc=1440440}}</ref> It binds to molecules on the surface of cells called [[Receptor (biochemistry)|receptors]] and drives the entry of the virus into the cell.<ref name="pmid12234525">{{cite journal |vauthors=Arias CF, Isa P, Guerrero CA, Méndez E, Zárate S, López T, Espinosa R, Romero P, López S |title=Molecular biology of rotavirus cell entry |journal=Archives of Medical Research |volume=33 |issue=4 |pages=356–361 |year=2002 |pmid=12234525 |doi=10.1016/S0188-4409(02)00374-0}}</ref> VP4 has to be modified by the [[protease]] enzyme [[trypsin]], which is found in the gut, into VP5* and VP8* before the virus is infectious.<ref name="pmid15010218">{{cite journal |vauthors=Jayaram H, Estes MK, Prasad BV |title=Emerging themes in rotavirus cell entry, genome organization, transcription and replication |journal=Virus Research |volume=101 |issue=1 |pages=67–81 |year=2004 |pmid=15010218 |doi=10.1016/j.virusres.2003.12.007}}</ref> VP4 determines how [[virulent]] the virus is and it determines the P-type of the virus.<ref name="pmid12167342">{{cite journal |vauthors=Hoshino Y, Jones RW, Kapikian AZ |title=Characterization of neutralization specificities of outer capsid spike protein VP4 of selected murine, lapine, and human rotavirus strains |journal=Virology |volume=299 |issue=1 |pages=64–71 |year=2002 |pmid=12167342 |doi=10.1006/viro.2002.1474|doi-access=free }}</ref> In humans there is an association between the [[blood group]] ([[Lewis antigen system]], [[ABO blood group system]] and [[secretor status]]) and susceptibility to infection. Non-secretors seem resistant to infection by types P[4] and P[8], indicating that blood group antigens are the receptors for these genotypes.<ref name="pmid24523471">{{cite journal |vauthors=Van Trang N, Vu HT, Le NT, Huang P, Jiang X, Anh DD |title=Association between norovirus and rotavirus infection and histo-blood group antigen types in Vietnamese children |journal=Journal of Clinical Microbiology |volume=52 |issue=5 |pages=1366–1374 |year=2014 |pmid=24523471 |pmc=3993640 |doi=10.1128/JCM.02927-13 }}</ref> This resistance is dependent on the rotavirus genotype.<ref name="pmid32192193">{{cite journal |vauthors=Sharma S, Hagbom M, Svensson L, Nordgren J |title=The Impact of Human Genetic Polymorphisms on Rotavirus Susceptibility, Epidemiology, and Vaccine Take |journal=Viruses |volume=12 |issue=3 |date=March 2020 |page=324 |pmid=32192193 |pmc=7150750 |doi=10.3390/v12030324 |url=|doi-access=free }}</ref>

VP6 forms the bulk of the capsid. It is highly [[antigen]]ic and can be used to identify rotavirus species.<ref name="pmid9015109" /> This protein is used in laboratory tests for rotavirus infections.<ref name="pmid6321549">{{cite journal |vauthors=Beards GM, Campbell AD, Cottrell NR, Peiris JS, Rees N, Sanders RC, Shirley JA, Wood HC, Flewett TH |title=Enzyme-linked immunosorbent assays based on polyclonal and monoclonal antibodies for rotavirus detection |journal=Journal of Clinical Microbiology |volume=19 |issue=2 |pages=248–54 |year=1984|doi=10.1128/JCM.19.2.248-254.1984 |pmid=6321549 |url=http://jcm.asm.org/cgi/reprint/19/2/248 |format=PDF |pmc=271031 }}</ref>

VP7 is a [[glycoprotein]] that forms the outer surface of the virion. Apart from its structural functions, it determines the G-type of the strain and, along with VP4, is involved in [[Immunity (medical)|immunity]] to infection.<ref name="pmid16913048" />