简介:TheaimofthisstudywastoexplorethemolecularbasisfortheattenuationoftheJapaneseencephalitisvirus(JEV)vaccinestrainSA14-14-2.ThevirulenceofSA14wildJapaneseencephalitisvirus(JEV)anditsseveralattenuatedviruseswastestedbyintracerebral(i.c.)orintraperitonial(i.p.)inoculationof10-12gmice.Thestabilityofneuroattenuationwastestedbyonepassageinsucklingmousebrain.TheEproteingenesofthoseviruseswereamplifiedbyPCR,sequencedandcompared.Threeattenuatedvirusstrains,SA14-14-2vaccinevirus,SA14-9-7andSA14-5-3,didnotexhibitlethalinfectionsbyi.c.ori.p.inoculationof10-12gmiceandreverttothevirulence.Theothervirusstrain,SA14-12-1-7,showednoneuroinvasivenessbyi.p.inoculationbutresidualneurovirulencebyi.c.inoculationandrevertedtohighvirulenceafteronebrainpassage.ComparisonoftheEproteingenesequencesofthefivevirusstrainsindicatedthatthereweredifferencesoftwelvenucleotidesandeightaminoacidsbetweentheparentstrainSA14andvaccinestrainSA14-14-2,ofwhichsixaminoacids(E-107,E-176,E-439,E-138,E-279,E-315)exhibitedchangescommontothoseofSA14-9-7andSA14-5-3,threesubstitutionscommontoSA14-12-1-7.TwoaminoacidsubstitutionsatthesitesE177(T→A)andE264(Q→H)areuniquetotheSA14-14-2vaccinevirus.TheresultssuggestthatthemutationsofE-107(Leu→Phe),E-176(He→Val),andE-439(Lys→Arg)maycontributefortheattenuationofneuroinvasivenessandpartiallyfortheattenuationofneurovirulence,themutationsofE-138,E-279,E-315maynotonlycriticaltotheneuroattenuationbutalsotoitsstability.
简介:【摘要】新冠疫情对世界各地各个方面的发展都有着非常深远的影响,尤其是广大居民的医疗健康方面。不仅是新冠病毒引起的医疗水平增长,也是由于新冠病毒的扩散对居民生活方式等有所改变,进而引起的健康水平的变化。本文根据北京某航空公司地面服务人员疫情前后的体检状况为基础数据,并通过对2019年已经2021年这两个时期的调查结果进行对比研究,分析疫情前后该公司人员各种体检项目的检出比例变化,探讨心冠疫情对航空公司地面服务人员的身体状况的影响,进而得出新冠疫情发生后,该公司员工的整体身体状况有所下降的结论。