B型肝炎病毒的蝙蝠

StephenW

Hepatitis B Viruses in Bats
by Vincent Racaniello
Saturday, October 19, 2013 at 06:45 AM EDT

Hepatitis B virus (HBV, illustrated) is a substantial human pathogen. WHO estimates that there are now 240,000,000 individuals chronically infected with HBV worldwide, of which 25% will die from chronic liver disease or hepatocellular carcinoma. The hepatitis B virus vaccine is highly effective at preventing infection. Because there are no known animal reservoirs of the virus, it is believed that HBV could be globally eradicated. The recent finding of HBV in bats raises the possibility of zoonotic introduction of the virus.

Serum and liver samples from 3,080 bats from Panama, Brazil, Gabon, Ghana, Germany, Papua New Guinea, and Australia were screened for HBV-like sequences by polymerase chain reaction (PCR). Ten positive specimens were found from three bat species: Uroderma bilobatum from Panama, and Hipposideros cf. ruber and Rhinolophus alcyone from Gabon. The complete viral genome sequence was determined for 9 of the positive specimens. Phylogenetic analysis revealed that the bat viruses form three different lineages, and that each virus differs by at least 35% from known hepadnaviruses.

The virus from Hipposideros cf. ruber has been named roundleaf bat HBV, while those from Rhinolophus and Uroderma have been named horshoe bat HBV, and tent-making bat HBV.

Viral DNA in the liver of Hipposideros bats was found to be higher than in other organs or serum. Some lymphocyte infiltration was observed in the liver of these animals, as well as deposits of viral DNA within hepatocytes. These observations indicate that the bat HBV viruses likely replicate in the bat liver and cause hepatitis.

Serological studies revealed that hepadnaviruses are widespread in Old World bats: antibodies against bat hepadnaviruses were detected in 18% of hipposiderid bats and 6.3% of rhinolophid bats.

An important question is whether these three bat hepadnaviruses can infect human cells. Only tent-making bat HBV could infect primary human hepatocytes, which occurred via the human HBV cell receptor, sodium taurocholate cotransporting polypeptide. However serum from humans that had been immunized with HBV vaccine did not block infection of human hepatocytes with this virus.

These observations show that viruses related to human HBV are replicating in the liver of bats. Earlier this year another hepadnavirus was identified in long-fingered bats (Miniopterus fuliginosus) in Myanmar. The complete genome sequence was obtained and virus particles were observed in bat liver tissues.

The finding of hepadnaviruses in bats raise many interesting questions. The first is whether human HBV originated by infection with bat HBV, either by consumption of bat meat or another mode of transmission. How long ago this occurred is not known. It has been suggested that HBV has been in humans for at least 15,000 years. Some avian species contain avihepadnaviral sequences integrated into their genome, indicating that these viruses originated at least 19 million years ago.

These findings also raise many questions about the pathogenesis of hepadnaviral infection in bats, including the mode of transmission (in humans, the virus is transmitted by exposure to blood, e.g. by injection or during childbirth), and whether chronic infections can occur as they do in humans.

Finally it is interesting to consider the zoonotic potential of tent-making bat HBV, which can infect human cells. Because bat hepadnaviruses are genetically distinct from HBV, current serological and nucleic acid screening programs would not detect human infections. The authors suggest that human and non-human primate sera from areas in which these bat viruses were isolated should be screened using assays that detect the bat hepadnaviruses. Without such information we do not know if these viruses currently infect humans.
This article originally appeared on virology blog.

StephenW

B型肝炎病毒的蝙蝠
Vincent拉卡涅洛的
周六， 10月19日， 2013年在美国东部时间上午6时45分，

B型肝炎病毒（HBV ，图文并茂）是一个重大的人类病原体。世卫组织估计，目前有240,000,000人感染慢性乙肝病毒在全球范围内，其中25％将死于慢性肝病或肝癌。 B型肝炎病毒疫苗是非常有效地防止感染。因为没有任何已知的动物宿主的病毒，它被认为HBV可以在全球范围内根除。最近发现乙肝病毒在蝙蝠引发人畜共患病毒传入的可能性。

通过聚合酶链反应（PCR） ，血清和肝脏样本进行了筛选，从3,080只蝙蝠从巴拿马，巴西，加蓬，加纳，德国，巴布亚新几内亚和澳大利亚HBV -序列。 10阳性标本发现，从三个的蝙蝠种类： Uroderma bilobatum来自巴拿马和蹄比照。曲霉和菊头蝠ALCYONE从加蓬。完整的病毒基因组序列被确定为阳性的样本9 。系统发育分析表明，蝙蝠病毒形成三个不同的谱系，每个病毒至少35 ％从已知嗜肝DNA病毒不同。

的病毒从蹄比照。曲霉已被命名为蝙蝠HBV roundleaf ，而那些已经从菊头蝠和Uroderma名为horshoe蝙蝠HBV和帐篷蝙蝠HBV 。

蹄拍在肝脏中的病毒DNA被认为是高于在其他器官或血清。这些动物中，以及存放在肝细胞内的病毒DNA在肝脏中的某些观察到的淋巴细胞浸润。这些观察表明，蝙蝠的乙肝病毒可能在蝙蝠肝脏和引起肝炎复制。

血清学研究表明，嗜肝DNA病毒广泛存在于旧世界的蝙蝠：蝙蝠嗜肝DNA病毒抗体检测蹄蝠的18％和6.3 ％ rhinolophid蝙蝠。

一个重要的问题是这三个蝙蝠嗜肝DNA病毒是否能感染人类细胞。帐篷蝙蝠HBV感染主要的人类肝细胞，从而发生通过人类的HBV细胞受体，牛磺胆酸钠cotransporting多肽。然而，血清人类已接种乙肝疫苗并不能阻止人类肝细胞感染了这种病毒。

这些观察结果表明，与人HBV病毒复制的蝙蝠在肝脏。今年早些时候，另一种嗜肝病毒被确定在长指蝙蝠（折翅fuliginosus ）在缅甸。完整的基因组序列得到蝙蝠肝组织中观察到病毒颗粒。

蝙蝠嗜肝DNA病毒的发现提出了许多有趣的问题。首先是人类起源与蝙蝠HBV感染HBV ，无论是通过食用蝙蝠肉或其他传输模式。那是多久以前发生这种情况是不知道。曾有人建议， HBV已经在人类至少15,000年。一些禽流感的物种包含avihepadnaviral的的集成到自己的基因组序列，表明这些病毒至少有19万年前起源。