Tilapia Lake Virus(TiLV)disease:Current status of understanding

Tilapia Lake Virus(TiLV)disease is an emerging and transboundary disease of tilapia cultures,causing mortality up to 90%globally.TiLV is a negative sense single stranded RNA virus belongs to family Amnoonviridae,genus Tilapinevirus and species Tilapia tilapinevirus.The first TiLV outbreak to fishes was reported from Israel followed by other countries viz.,Ecuador,Colombia,Egypt,Thailand,Chinese Taipei,India,Malaysia,Bangladesh,Uganda,Tanzania,Peru,Mexico,Philippines,Indonesia,and USA.All the life stages of Tilapia(belonging to the family Cichlidae)are vulnerable to TiLV infection.However,river barb and giant gourami have also been found susceptible to TiLV infection.The virus infects the vital organs of the fish,including eyes,brain,and liver.The notable pathological finding of this disease includes syncytial cell formation and massive hepatocellular necrosis with pyknotic and karyolytic nuclei in the liver cells of infected fish.The disease is very contagious and spreads through both horizontal and vertical transmission.Several sensitive and rapid molecular diagnostic tools like reverse transcriptase polymerase chain reaction(RT-PCR),RT-quantitative PCR(RT-qPCR),loop-mediated isothermal amplification(LAMP)have been developed for early detection of the virus.Till date,no comprehensive control measures have been developed throughout the globe,although aggressive work on this line is going on.Implementations of strict good management practices,including quarantine protocols,are the only available option to combat the outbreak and spread of the disease.This review emphasizes the etiology,occurrence and distribution,mode of transmission,pathology and pathogenesis,diagnosis,possible control measures,and challenges of TiLV disease.

基于核苷酸序列的罗非鱼罗湖病毒分子流行病学分析

通过对NCBI数据库里的罗湖病毒(tilapia lake virus,TiLV)核苷酸序列进行生物信息学分析,了解罗湖病毒在全球的流行情况和中国罗非鱼(tilapia)养殖中罗湖病毒的感染情况。该研究将第3个片段的序列比对结果中的罗湖病毒分成12个簇群,通过对片段进行motif序列富集,显示motif序列每个位点的碱基。对从广东各地区罗非鱼养殖场采集到的302份样本进行检测,结果显示,均未检测出罗湖病毒阳性,并且显示motif序列位点的碱基非常稳定。通过对罗湖病毒进行分子流行病学分析,中国虽未有罗湖病毒流行的趋势,但在进出口贸易中仍要严格防控罗湖病毒的输入,并应对这些非常保守的motif的相关功能进行深入研究。