中華肝臟病雜志　臨床肝膽病雜志　《肝臟》雜志　聯(lián)合社評

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·社評與爭鳴·

HBV RNA病毒樣顆粒的潛在臨床意義

中華肝臟病雜志臨床肝膽病雜志《肝臟》雜志聯(lián)合社評

最近的研究結(jié)果證實慢性乙型肝炎患者血清中存在的HBV RNA為3.5 kb的前基因組RNA(pgRNA)，這些pgRNA 存在于形態(tài)結(jié)構(gòu)類似于丹顆粒的病毒樣顆粒中。由于pgRNA 只能由位于感染的肝細(xì)胞核內(nèi)的病毒共價閉合環(huán)狀DNA(cccDNA)，且其產(chǎn)生過程不受核苷(酸)類抗病毒藥物的影響，因此血清病毒RNA 應(yīng)能夠反映接受治療的患者肝細(xì)胞內(nèi)cccDNA的存在及轉(zhuǎn)錄活性。據(jù)此推測，血清病毒RNA 可作為一個潛在的指導(dǎo)核苷(酸)類似物安全停藥的指標(biāo)。基于小樣本停藥隊列研究的結(jié)果顯示停藥點血清中HBV RNA的確與慢性乙型肝炎停藥后的病毒學(xué)反彈相關(guān)。

肝炎，乙型，慢性； 肝炎病毒，乙型； 治療； 核苷(酸)類似物

目前，核苷(酸)類藥物(NUCs)廣泛用于治療慢性乙型肝炎(CHB)，其主要通過抑制病毒的逆轉(zhuǎn)錄和DNA合成發(fā)揮抗病毒作用。由于NUCs不能清除cccDNA，一旦停藥后往往會發(fā)生病毒學(xué)反彈和疾病復(fù)發(fā)，因此很難實現(xiàn)CHB的臨床治愈，需要長期甚至終生服藥。

早在1996年，Kock等[1]已經(jīng)在慢性HBV感染者的血清中檢測到了HBV RNA。隨后，在接受抗病毒治療的CHB患者血清中發(fā)現(xiàn)HBV RNA水平與患者病毒學(xué)應(yīng)答和預(yù)后有關(guān)[2-4]。然而，對于血清中HBV RNA的來源和存在方式一直缺少足夠的認(rèn)識。近期，北京大學(xué)醫(yī)學(xué)部基礎(chǔ)醫(yī)學(xué)院病原生物學(xué)系魯鳳民與廈門大學(xué)夏寧邵教授、重慶醫(yī)科大學(xué)第二附屬醫(yī)院任紅教授和中山大學(xué)第三醫(yī)院高志良教授團隊聯(lián)合發(fā)表在JournalofHepatology上的 “Serum hepatitis B virus RNA is encapsidated pregenome RNA that may be associated with persistence of viral infection and rebound”文章對此問題進(jìn)行了探討[5]。

該研究證實HBV感染者血清中的HBV RNA為HBV前基因組RNA(pregenomic RNA, pgRNA)，其來源可能為核衣殼包裹的pgRNA在未啟動逆轉(zhuǎn)錄步驟的情況下，直接獲得包膜并從感染的肝細(xì)胞中釋放出來，因該病毒顆粒所含的核酸為pgRNA，稱之為“HBV RNA病毒樣顆?！薄?/p>

該研究提示：(1) 因HBV pgRNA由感染肝細(xì)胞核內(nèi)的cccDNA轉(zhuǎn)錄產(chǎn)生，理論上血清中HBV RNA病毒樣顆粒的存在及水平能夠反映cccDNA的狀態(tài)(包括cccDNA存在水平及其轉(zhuǎn)錄活性)；(2)由于HBV RNA病毒樣顆粒的形成不存在逆轉(zhuǎn)錄生成病毒DNA負(fù)鏈和合成DNA正鏈的過程，因此NUCs對HBV RNA病毒樣顆粒的產(chǎn)生無直接的抑制作用，這可能是導(dǎo)致目前臨床上慢乙肝患者抗病毒治療難以實現(xiàn)臨床治愈的原因之一；(3)HBV RNA病毒樣顆粒的存在將對新藥設(shè)計的思路產(chǎn)生影響，即研發(fā)針對HBcAg生成和核衣殼裝配的抗病毒藥物可能比NUCs更有意義；(4) 通過對既往接受NUCs抗病毒治療后CHB患者停藥隊列的回顧性研究，提出血清HBV RNA可用于NUCs抗病毒治療安全停藥指標(biāo)的概念；(5)HBV RNA病毒樣顆粒因具有病毒包膜，推測其可能具有感染肝細(xì)胞的能力。

近年來有關(guān)血清中HBV RNA的研究逐漸受到關(guān)注，但仍有許多未知需要探索。有關(guān)HBV RNA病毒樣顆粒，亟需從如下方面探尋其理論和臨床意義：(1)HBV RNA病毒樣顆粒是否能夠在肝細(xì)胞建立感染，這將直接影響到未來病毒學(xué)的核酸分類；(2)血清中HBV RNA水平是否能準(zhǔn)確反映肝細(xì)胞內(nèi)cccDNA的狀態(tài)；(3)由于HBV感染者中HBV基因可整合到宿主基因組[6-8]，且某些整合的HBV基因片段仍可產(chǎn)生HBsAg[9-10]，因此少數(shù)CHB患者在按照停藥標(biāo)準(zhǔn)停藥時，其血清中HBsAg水平不一定能很好地反映肝細(xì)胞內(nèi)cccDNA的狀態(tài)?；贖BV pgRNA必須經(jīng)過完整的cccDNA轉(zhuǎn)錄才能產(chǎn)生，所以血清HBV RNA是否可作為抗病毒治療臨床治愈和安全停藥的指標(biāo)，以及是否優(yōu)于血清HBsAg的檢測，尚需通過大樣本的前瞻性研究進(jìn)一步闡明。

需要強調(diào)的是，該研究由國內(nèi)多家教學(xué)科研、臨床單位通力合作完成。未來，將繼續(xù)這種基礎(chǔ)與臨床醫(yī)學(xué)的合作，以進(jìn)一步探索HBV RNA病毒樣顆粒在HBV 感染預(yù)防、診斷和治療方面的意義。

(魯鳳民王杰莊輝)

[1]Kock J, Theilmann L, Galle P, et al. Hepatitis B virus nucleic acids associated with human peripheral blood mononuclear cells do not originate from replicating virus. Hepatology, 1996, 23: 405-413.

[2]JansenL, Kootstra NA, van Dort KA, et al. Hepatitis B virus pregenomic RNA is present in virions in plasma and is associated with a response to pegylated interferon alfa-2a and nucleos(t)ide analogues. J Infect Dis, 2016, 213: 224-232.

[3]Tsuge M, Murakami E, Imamura M, et al. Serum HBV RNA and HBeAg are useful markers for the safe discontinuation of nucleotide analogue treatments in chronic hepatitis B patients. J Gastroenterol, 2013, 48: 1188-1204.

[4]van Bommel F, Bartens A, Mysickova A, et al. Serum hepatitis B virus RNA levels as an early predictor of hepatitis B envelope antigen seroconversion during treatment with polymerase inhibitors. Hepatology, 2015, 61: 66-76.

[5]Wang J, Shen T, Huang X B, et al. Serum hepatitis B virus RNA is encapsidated pregenome RNA that may be associated with persistence of viral infection and rebound. J Hepatol, 2016[Epub ahead of print]

[6]Sung WK, Zheng H, Li S, et al. Genome-wide survey of recurrent HBV integration in hepatocellular carcinoma. Nat Genet, 2012, 44: 765-769.

[7]Jiang S, Yang Z, Li W, et al. Re-evaluation of the carcinogenic significance of hepatitis B virus integration in hepatocarcinogenesis. PLoS One, 2012, 7: e40363.

[8]Li X, Zhang J, Yang Z, et al. The function of targeted host genes determines the oncogenicity of HBV integration in hepatocellular carcinoma. J Hepatol, 2014, 60: 975-984.

[9]Shouval D, Rager-Zisman B, Quan P, et al. Role in nude mice of interferon and natural killer cells in inhibiting the tumorigenicity of human hepatocellular carcinoma cells infected with hepatitis B virus. J Clin Invest, 1983, 72: 707-717.

[10]Shouval D, Reid LM, Chakraborty PR, et al. Tumorigenicity in nude mice of a human hepatoma cell line containing hepatitis B virus DNA. Cancer Res, 1981, 41: 1342-1350.

(本文編輯：錢燕)

Potential clinical significance of HBV RNA virus-like particle

LUFeng-min,WANGJie,ZHUANGHui.

DepartmentofMicrobiology&InfectiousDiseaseCenter,SchoolofBasicMedicine,PekingUniversityHealthScienceCenter,Beijing100191,ChinaCorrespondingauthor:LUFeng-min,Email:lu.fengmin@bjmu.edu.cn

Our recent studies confirmed that the HBV RNAs present in the serum of chronic hepatitis B (CHB) patients are pregenomic RNAs (pgRNAs) with a size of 3.5 kb. These pgRNAs are located in viruslike particles whose morphological structure is similar to that of Dan particles. Since pgRNAs can only be transcribed from the covalently closed circular DNA (cccDNA) located in the nuclear of infected hepatocytes, and the production of pgRNAs is not affected by nucleos(t)ide analogues (NUCs), the presence of viral RNA in serum can reflect the presence of cccDNA in hepatocytes and its transcriptional activity in patients treated with medication. It can be inferred that serum viral RNA can be used as a potential index for safe withdrawal of NUCs. Our results based on a small-sample cohort show that the presence of HBV RNA in serum at the time of drugs withdrawal is indeed associated with virological rebound after drug withdrawal.

Hepatitis B, chronic; Hepatitis B virus; Therapy; Nucleot(s)ide analogues

100191北京大學(xué)醫(yī)學(xué)部基礎(chǔ)醫(yī)學(xué)院病原生物學(xué)系

魯鳳民，Email: lu.fengmin@bjmu.edu.cn

2016-08-08)