WordNet

a harmful or corrupting agency; "bigotry is a virus that must not be allowed to spread"; "the virus of jealousy is latent in everyone"
(virology) ultramicroscopic infectious agent that replicates itself only within cells of living hosts; many are pathogenic; a piece of nucleic acid (DNA or RNA) wrapped in a thin coat of protein
a software program capable of reproducing itself and usually capable of causing great harm to files or other programs on the same computer; "a true virus cannot spread to another computer without human assistance" (同)computer virus
the process whereby something is shed (同)sloughing

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ビールス,ろ過性病原体

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2012/10/11 21:14:53」(JST)

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Viral shedding refers to the successful reproduction, expulsion, and host-cell infection caused by virus progeny. Once replication has been completed and the host cell is exhausted of all resources in making viral progeny, the viruses may begin to leave the cell by several methods^[1].

The term is used to refer to shedding from a single cell, shedding from one part of the body into another part of the body,^[2] and shedding from bodies into the environment where the viruses may infect other bodies.^[3]

Via budding

"Budding" through the cell envelope, in effect using the cell's membrane for the virus itself is most effective for viruses that need an envelope in the first place. These include enveloped viruses such as HSV, SARS or smallpox. Prior to budding, the virus may put its own receptor onto the surface of the cell in preparation for the virus to bud through, forming an envelope with the viral receptors already on it. This process will slowly use up the cell membrane and eventually lead to the demise of the cell. This is also how antiviral responses are able to detect virus infected cells^[4].

Via apoptosis

By forcing the cell to undergo apoptosis or cell suicide, release of progeny into the extracellular space is possible. However, apoptosis does not necessarily result in the cell simply popping open and spilling its contents into the extracellular space. Rather, apoptosis is usually controlled and results in the cell's genome being chopped up, before apoptotic bodies of dead cell material clump off the cell to be absorbed by macrophages. This is a good way for a virus to get into macrophages either to infect them or simply travel to other tissues in the body. Although this process is primarily used by non-enveloped viruses, enveloped viruses may also use this. HIV is an example of an enveloped virus that exhibits this process for the infection of macrophages^[5].

Via exocytosis

In exocytosis the host cell is not destroyed. Viral progeny are synthesized within the cell and the host cell's transport system is used to enclose vacuoles of virus progeny for release into the extracellular space. This is used primarily by non-enveloped viruses, although enveloped viruses display this too. An example is the use of recycling viral particle receptors in the enveloped varicella-zoster virus^[6].

References

^ N.J. Dimmock et al. "Introduction to Modern Virology, 6th edition." Blackwell Publishing, 2007.
^ [1] Massachusetts Department of Public Health - Rabies Control Plan - CHAPTER 1: GENERAL INFORMATION - "Definitions as Used in this Document [...] Shedding - The release of rabies virus from the salivary glands into the saliva."
^ J Infect Dis. 1979 Oct;140(4):610-3 article Viral shedding patterns of children with influenza B infection
^ Owen Pornillos, Jennifer E. Garrus and Wesley I. Sundquist. "Mechanisms of enveloped RNA virus budding." Trends in Cell Biology, Volume 12, Issue 12, 1 December 2002, Pages 569-579
^ Sheila A. Stewart, Betty Poon, Joo Y. Song, and Irvin S. Y. Chen. "Human Immunodeficiency Virus Type 1 Vpr Induces Apoptosis through Caspase Activation." Journal of Virology, April 2000, p. 3105-3111, Vol. 74, No. 7
^ J K Olson and C Grose. "Endocytosis and recycling of varicella-zoster virus Fc receptor glycoprotein gE: internalization mediated by a YXXL motif in the cytoplasmic tail." J Virol. 1997 May; 71(5): 4042–4054.

UpToDate Contents

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1. 性器単純ヘルペスウイルス感染の疫学、臨床症状、および診断 epidemiology clinical manifestations and diagnosis of genital herpes simplex virus infection
2. ウイルス誘発性の喘鳴および喘息：概要 virus induced wheezing and asthma an overview
3. E型肝炎ウイルス感染 hepatitis e virus infection
4. 性器単純ヘルペスウイルス感染と妊娠 genital herpes simplex virus infection and pregnancy
5. 成人における季節性インフルエンザの臨床症状 clinical manifestations of seasonal influenza in adults

English Journal

Current Concepts for Genital Herpes Simplex Virus Infection: Diagnostics and Pathogenesis of Genital Tract Shedding.

Johnston C1, Corey L2.
Clinical microbiology reviews.Clin Microbiol Rev.2016 Jan;29(1):149-61. doi: 10.1128/CMR.00043-15.
SUMMARYHerpes simplex virus 2 (HSV-2) is a DNA virus that is efficiently transmitted through intimate genital tract contact and causes persistent infection that cannot be eliminated. HSV-2 may cause frequent, symptomatic self-limited genital ulcers, but in most persons infection is subclinical. Howe
PMID 26561565

Oral and Vaginal Tenofovir for Genital Herpes Simplex Virus Type 2 Shedding in Immunocompetent Women: A Double-Blind, Randomized, Cross-over Trial.

Bender Ignacio RA1, Perti T2, Magaret AS3, Rajagopal S4, Stevens CE5, Huang ML6, Selke S7, Johnston C1, Marrazzo J2, Wald A8.
The Journal of infectious diseases.J Infect Dis.2015 Dec 15;212(12):1949-56. doi: 10.1093/infdis/jiv317. Epub 2015 Jun 4.
BACKGROUND: Tenofovir is a potent anti-human immunodeficiency virus (HIV) agent that decreased risk of herpes simplex virus type 2 (HSV-2) acquisition in HIV pre-exposure prophylaxis trials. Whether tenofovir has utility in established HSV-2 disease is unclear.METHODS: We randomized immunocompetent
PMID 26044291

Spatiotemporal interplay of severe acute respiratory syndrome coronavirus and respiratory mucosal cells drives viral dissemination in rhesus macaques.

Liu L1, Wei Q2, Nishiura K1, Peng J1, Wang H1, Midkiff C3, Alvarez X3, Qin C2, Lackner A3, Chen Z1.
Mucosal immunology.Mucosal Immunol.2015 Dec 9. doi: 10.1038/mi.2015.127. [Epub ahead of print]
Innate immune responses have a critical role in the control of early virus replication and dissemination. It remains unknown, however, how severe acute respiratory syndrome coronavirus (SARS-CoV) evades respiratory innate immunity to establish a systemic infection. Here we show in Chinese macaques t
PMID 26647718

Japanese Journal

The kinetics of urinary shedding of BK virus in children with renal disease

Yamamoto Yasuto,Morooka Masashi,Ihira Masaru [他]
Microbiology and immunology 59(1), 37-42, 2015-01
NAID 40020351702

Prevalence of porcine reproductive and respiratory syndrome virus detection in aborted fetuses, mummified fetuses and stillborn piglets using quantitative polymerase chain reaction

, , ,
Journal of Veterinary Medical Science advpub(0), 2015
… The objective of the present study was to investigate the prevalence of porcine reproductive and respiratory syndrome (PRRS) virus detection in aborted fetuses (n=32), mummified fetuses (n=30) and stillborn piglets (n=27) from 10 swine herds in Thailand using quantitative polymerase chain reaction (qPCR). … The results revealed that 67.4% (60/89) of the specimens contained PRRS virus. …
NAID 130005061027

Fatal cases of human infection with avian influenza A (H7N9) virus in Shanghai, China in 2013

, , , , , , , , , , , , ,
BioScience Trends 9(1), 73-78, 2015
… Among six patients for whom the duration of viral shedding was available, the median duration of viral shedding after oseltamivir treatment was 17 days. … Late antiviral treatment and a long duration of viral shedding may be associated with a fatal outcome in these patients. …
NAID 130005054679