乙型肝炎病毒基因亚型研究进展

近年来,各国学者对乙型肝炎病毒(HBV)基因型及其亚型的研究十分关注.HBV基因型不仅能反映核酸变异程度和病毒种系发生关系,而且与感染者的临床表现、预后及疗效有关.目前,根据HBV全基因组序列差异≥8%,或S基因序列≥4%,将HBV分为A、B、C、D、E、F、G、H等8个基因型[1-4],但基因型H是否是独立于F的一个新基因型,还有待进一步证实.各基因型之间还存在混合感染,如B与C、C与D混合感染等[5,6].有人认为,混合感染可能与重叠感染或基因型之间的同源重组或部分转换有关.值得注意的是:近年来,除研究HBV基因型外,对HBV基因亚型也进行了深入研究,发现A基因型可进一步分为Aa和Ae亚型[7];B型可分为B1(Bj)、B2(Ba)、B3和B4亚型[8];C型可分为C1、C2、C3和C4亚型;D型可分为D1、D2、D3和D4亚型,F型可分为F1和F2亚型等[9,10](见表1).

Molecular epidemiology demonstrates that imported and local strains circulated during the 2014 dengue outbreak in Guangzhou, China

The dengue virus （DENV） is a vital global public health issue. The 2014 dengue epidemic in Guangzhou, China, caused approximately 40,000 cases of infection and five deaths. We carried out a comprehensive investigation aimed at identifying the transmission sources in this dengue epidemic. To analyze the phylogenetics of the 2014 dengue strains, the envelope （E） gene sequences from 17 viral strains isolated from 168 dengue patient serum samples were sequenced and a phylogenetic tree was reconstructed. All 17 strains were serotype I strains, including 8 genotype I and 9 genotype V strains. Additionally, 6 genotype I strains that were probably introduced to China from Thailand before 2009 were widely transmitted in the 2013 and 2014 epidemics, and they continued to circulate until 2015, with one affinis strain being found in Singapore. The other 2 genotype I strains were introduced from the Malaya Peninsula in 2014. The transmission source of the 9 genotype V strains was from Malaysia in 2014. DENVs of different serotypes and genotypes co-circulated in the 2014 dengue outbreak in Guangzhou. Moreover, not only had DENV been imported to Guangzhou, but it had also been gradually exported, as the viruses exhibited an enzootic transmission cycle in Guangzhou.

Isolation,Characterization,and Phylogenetic Analysis of Two New Crimean-Congo Hemorrhagic Fever Virus Strains from the Northern Region of Xinjiang Province,China

Crimean-Congo hemorrhagic fever(CCHF)caused by the CCHF virus(CCHFV)is a tick-borne natural focal disease with a mortality rate of approximately 50%.CCHFV is widely prevalent in Africa,southern Asia,the Middle East,and southeast Europe.CCHF outbreaks have been reported previously in Xinjiang province,China,especially in its southern region.Epidemiological surveys conducted on ticks and animals have revealed the presence of CCHFV strains in ticks,rodents,and infected individuals from cities and counties in southern Xinjiang.Phylogenetic analyses revealed that the Chinese CCHFV strains belong to one genotype,based on complete sequences of the S segments of its negative-stranded RNA genome.The present study reports two new CCHFV strains isolated from Hyalomma asiaticum asiaticum ticks collected from Fukang City and Wujiaqu City in the northern region of Xinjiang.Viral characteristics and their evolutionary relationships were analyzed through metagenomic and reverse-transcription PCR analyses;these analyses indicated that the genotype of both strains was different from that of other Chinese strains.Furthermore,previous reports of CCHFV in Xinjiang were reviewed and phylogenetic analyses were performed.CCHFV was found to prevail in Fukang City in Junggar Basin for more than 20 years,and that Fukang City and Wujiaqu City are considered natural reservoirs of different genotypes of CCHFV strains.Our findings facilitate the understanding of CCHFV distribution in Xinjiang province and provide insights into the evolutionary relationships among Chinese CCHFV strains.

Prevalence and Phylogenetic Analysis of Crimean-Congo Hemorrhagic Fever Virus in Ticks from Different Ecosystems in Xinjiang,China

The Crimean-Congo hemorrhagic fever virus(CCHFV),a member of the genus Orthonairovirus and family Nairoviridae,is transmitted by ticks and causes severe hemorrhagic disease in humans.To study the epidemiology of CCHFV in different ecosystems in Xinjiang,China,a total of 58,932 ticks were collected from Tarim Basin,Junggar Basin,Tianshan Mountain,and Altai Mountain from 2014 to 2017.Hyalomma asiaticum asiaticum was the dominant tick species in Tarim and Junggar basins,whereas Dermacentor nuttalli and Hyalomma detritum were found in Tianshan Mountain and Altai Mountain,respectively.Reverse transcription-polymerase chain reaction of the CCHFV small(S)genome segment was used for the molecular detection.The CCHFV-positive percentage was 5.26%,6.85%,1.94%,and 5.56% in Tarim Basin,Junggar Basin,Tianshan Mountain,and Altai Mountain,respectively.Sequences of the S segment were used for phylogenetic analysis and the results showed that the newly identified CCHFV strains belonged to two clades.Our study confirms that H.asiaticum asiaticum is the major vector of CCHFV in desert habitats which is consistent with previous studies,and also suggests that H.detritum and D.nuttalli are emerging vectors for CCHFV in Xinjiang.Moreover,this study reports the presence of CCHFV in the mountain habitat of Xinjiang for the first time,suggesting that future surveillance of CCHFV should also include mountainous areas.

A new strain of Crimean-Congo hemorrhagic fever virus isolated from Xinjiang, China

Crimean-Congo hemorrhagic fever virus(CCHFV) is a highly pathogenic tick-borne virus with a fatality rate of up to 50% in humans. CCHFV is widely distributed in countries around the world.Outbreaks of CCHFV infection in humans have occurred in prior years in Xinjiang Province, China.Epidemiological surveys have detected CCHFV RNA in ticks and animals; however, few isolates were identified. In this study, we identified and isolated a new CCHFV strain from Hyalomma asiaticum asiaticum ticks collected from north of Tarim Basin in Xinjiang, China. A preliminary investigation of infection and antigens expression of CCHFV was performed in newborn mice. The target tissues for CCHFV replication in newborn mice were identified. The analysis of the phylogenetic relationships with other Chinese strains suggested that diverse genotypes of CCHFV have circulated in Xinjiang for years. These findings provide important insights into our understanding of CCHFV infection and evolution as well as disease prevention and control for local residents.