WordNet

pursue a positive and satisfying existence; "You must accept yourself and others if you really want to live"
actually being performed at the time of hearing or viewing; "a live television program"; "brought to you live from Lincoln Center"; "live entertainment involves performers actually in the physical presence of a live audience" (同)unrecorded
abounding with life and energy; "the club members are a really live bunch"
charged with an explosive; "live ammunition"; "a live bomb"
exerting force or containing energy; "live coals"; "tossed a live cigarette out the window"; "got a shock from a live wire"; "live ore is unmined ore"; "a live bomb"; "a live ball is one in play"
highly reverberant; "a live concert hall"
in current use or ready for use; "live copy is ready to be set in type or already set but not yet proofread"
lead a certain kind of life; live in a certain style; "we had to live frugally after the war"
not recorded; "the opera was broadcast live"
of current relevance; "a live issue"; "still a live option"
true to life; lifelike; "the living image of her mother"
people who are still living; "save your pity for the living"
(informal) absolute; "she is a living doll"; "scared the living daylights out of them"; "beat the living hell out of him"
(used of minerals or stone) in its natural state and place; not mined or quarried; "carved into the living stone";
pertaining to living persons; "within living memory"
still in active use; "a living language"
immunogen consisting of a suspension of weakened or dead pathogenic cells injected in order to stimulate the production of antibodies (同)vaccinum
Chinese distance measure; approximately 0.5 kilometers

PrepTutorEJDIC

『生きている』,生命がある / 《副詞[句]を伴って》〈人などが〉『生き続ける』 / 〈物事が〉長く続く,存続する / 《場所を表す副詞[句]を伴って》〈人などが〉『住む』,居住する / 《副詞[句]を伴って》『生活する』,暮らす / 生人を楽しむ,おもしろく桟らす / 《a+形容詞癌lifeを目的語にして》〈…を生活〉‘を'する / 〈思想など〉‘を'実銭する
《名詞の前にのみ用いて》『生きている』 / 『活気のある』 / (問題などが)当面の / 燃えている / (弾丸などが)まだ爆発してない,未発の / まだ動いている(働いている),有効な / 電流が通じている / (放走が)生の,実況の
『生きている』 / 生活の;生活に適した / 『現存の』,まだ使われている / 『生き生きした』,活気のある / 『生き写しの』 / 〈U〉生存;生活状態,暮らし / 〈U〉《a~,one's~》『生計』,暮らしの費用(livelihood) / 《the~》《複数扱い》生きている人々
牛痘種,痘苗(牛痘を起こすビールスで,天然痘予防のために人体に接種される) / (伝染病の病原菌から作った)ワクチン
lifeの複数形

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/05/26 16:37:50」(JST)

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An attenuated vaccine is a vaccine created by reducing the virulence of a pathogen, but still keeping it viable (or "live").^[1] Attenuation takes an infectious agent and alters it so that it becomes harmless or less virulent. These vaccines contrast to those produced by "killing" the virus (inactivated vaccine).

Examples

Examples of "live" (example attenuated) vaccines include:

Viral: measles vaccine, mumps vaccine, rubella vaccine, Live attenuated influenza vaccine (the seasonal flu nasal spray and the 2009 H1N1 flu nasal spray), chicken pox vaccine, oral polio vaccine (Sabin), rotavirus vaccine, and yellow fever vaccine.^[2] Rabies vaccines are now available in two different attenuated forms, one for use in humans, and one for animal usage.
Bacterial: BCG vaccine,^[2] typhoid vaccine^[3] and epidemic typhus vaccine.

Development

Viruses may be attenuated via passage of the virus through a foreign host, such as:

Tissue culture
Embryonated eggs
Live animals

The initial virus population is applied to a foreign host. One or more of these will possess a mutation that enables it to infect the new host. These mutations will spread, as the mutations allow the virus to grow well in the new host; the result is a population that is significantly different from the initial population, and thus will not grow well in the original host when it is re-introduced (hence is "attenuated"). This makes it easier for the host's immune system to eliminate the agent and create the immunological memory cells which will likely protect the patient if they are infected with a similar version of the virus in "the wild".

Administration

In an attenuated vaccine, live virus particles with very low virulence are administered. They will reproduce, but very slowly. Since they do reproduce and continue to present antigen beyond the initial vaccination, boosters are required less often. These vaccines are produced by growing the virus in tissue cultures that will select for less virulent strains, or by mutagenesis or targeted deletions in genes required for virulence. There is a small risk of reversion to virulence; this risk is smaller in vaccines with deletions. Attenuated vaccines also cannot be used by immunocompromised individuals.

Advantages of attenuated vaccines

Activates all phases of the immune system (for instance IgA local antibodies are produced)
Provides more durable immunity; boosters are required less frequently
Low cost
Quick immunity
Easy to transport/administer (for instance OPV for Polio can be taken orally, rather than requiring a sterile injection by a trained healthworker, as the inactivated form IPV does)
Initial "spotting" method first discovered by Easan Anand has very few side effects in comparison to injected antibody vaccines (e.g. tetanus)
Vaccines have strong beneficial non-specific effects. That is effects which go beyond the specific protective effects against the targeted diseases.^[4]

Disadvantages of attenuated vaccines

Secondary mutation can cause a reversion to virulence.^[5]
Can cause severe complications in immunocompromised patients.^[6]
Can be difficult to transport due to requirement to maintain conditions (e.g. temperature)

References

^ Badgett MR, Auer A, Carmichael LE, Parrish CR, Bull JJ (October 2002). "Evolutionary dynamics of viral attenuation". J. Virol. 76 (20): 10524–9. doi:10.1128/JVI.76.20.10524-10529.2002. PMC 136581. PMID 12239331.
^ ^a ^b "Immunization". Archived from the original on 7 March 2009. Retrieved 2009-03-10.
^ Levine MM, Ferreccio C, Black RE, Lagos R, San Martin O, Blackwelder WC (July 2007). "Ty21a live oral typhoid vaccine and prevention of paratyphoid fever caused by Salmonella enterica Serovar Paratyphi B". Clin. Infect. Dis. 45 Suppl 1: S24–8. doi:10.1086/518141?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dncbi.nlm.nih.gov. PMID 17582564.
^ Benn CS, Netea MG, Selin LK, Aaby P (13 May 2013). "A small jab - a big effect: nonspecific immunomodulation by vaccines.". Trends in immunology. 34 (9): 431–9. PMID 23680130. |accessdate= requires |url= (help)
^ Shimizu H, Thorley B, Paladin FJ et al. (December 2004). "Circulation of type 1 vaccine-derived poliovirus in the Philippines in 2001". J. Virol. 78 (24): 13512–21. doi:10.1128/JVI.78.24.13512-13521.2004. PMC 533948. PMID 15564462.
^ Kroger, Andrew T.; Ciro V. Sumaya; Larry K. Pickering; William L. Atkinson (2011-01-28). "General Recommendations on Immunization: Recommendations of the Advisory Committee on Immunization Practices (ACIP)". Morbidity and Mortality Weekly Report (MMWR) (Centers for Disease Control and Prevention). Retrieved 2011-03-11.

External links

Global Polio Eradication Initiative: Advantages and Disadvantages of Vaccine Types
CDC H1N1 Flu / 2009 H1N1 Nasal Spray Vaccine Q&A at the website of the US Centers for Disease Control and Prevention

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Japanese Journal

Modulation of systemic and mucosal immunity against an inactivated vaccine of Newcastle disease virus by oral co-administration of live attenuated Salmonella enterica serovar Typhimurium expressing chicken interleukin-18 and interferon-α