B型肝炎病毒polymerase基因區變異與慢性B肝急性發作之相關:縱式研究

背景與目的: 急性發作(AE)好發於慢性B肝帶原者，尤其是e抗原(HBeAg)呈陽性患者。在感染B型肝炎病毒期間，急性發作被認為和宿主免疫反應和病毒間的平衡被破壞有關，而HBV的變異或許會導致急性發作的產生。為了釐清這個疑惑，本研究主要去探討：(1)B型肝炎病毒polymerase基因區變異與慢性B肝急性發作之相關。(2)慢性B肝患者在歷經急性發作的過程中其血清ALT值和HBV DNA濃度以了解血清HBV DNA 濃度和ALT 值升高的相對應關係。(3)是否有特異的位點變異和急性發作有關。材料與方法: 我們收集了52位急性發作患者，在收案時(Baseline)、急性發作前(Tb)、急性發作時(Tp)及急性發作之後(Ta)共四個時間點，各別分析了他們的HBV Pol基因序列，並以重疊式病例對照研究法，納入了52位符合配對條件的對照組。總共有160個血清檢體納入研究，接著利用nested PCR將Pol基因區進行放大，並以直接定序的方法進行序列分析。最後，我們分析HBV演化行為及核苷酸/胺基酸變異和急性發作之間的相關。結果: 在Baseline時急性發作患者其血清ALT和HBV DNA皆顯著高於對照組。而在Baseline時病例組HBV Pol基因多樣顯著低於對照組 (9.68*10-3 vs. 11.7*10-3, p=0.031)，但在急性發作當時(Tp)則看不到這樣的相關(12.1*10-3 vs. 13.8*10-3, p=0.329)。以病例組來探討，急性發作當時(Tp)相較於其它時點(Baseline、Tb、Ta)其平均演化距離高，且達到統計顯著邊緣(12.1*10-3 vs. 10.2*10-3, p=0.071)。最後，經由Pol基因區逐點核苷酸/胺基酸單點變異篩選，我們發現在nt1080 (OR=0.32, p=0.0288)、 nt1126 (OR=0.33, p=0.0453)、 nt1242 (OR=0.34, p=0.0346)、 nt2619 (OR=0.32, p=0.0433)、nt2444 (OR=4.07, p=0.0157)、aa17 (OR=0.28, p=0.048)及aa46 (OR=4.28, p=0.0116)這些位點產生變異會和急性發作的發生有關。結論：我們的研究顯示並沒有很明顯的證據能說明病毒的歧異度會和急性發作的發生有關。但有些單核苷酸多型性或許可作為急性發作的預測因子。

關鍵字

慢性B 型肝炎； B 型肝炎病毒；急性發作；病毒演化；基因多樣性；病毒量

並列摘要

Background and Aims: Acute exacerbation (AE) occurs frequently in hepatitis B surface antigen (HBsAg) carriers, especially in those positive for HBeAg. During the course of persistent hepatitis B virus (HBV) infection, AE is likely related to the break of balance between virus and host immune response, and HBV genetic variation may trigger AE. The aim of this study was to clarify the association between HBV sequence variations and AE, and to investigate change in Pol gene sequence before, during, and after exacerbation. Materials and Methods: We prospectively studied 52 patients with exacerbation of hepatitis B Pol gene sequence using plasma sample collected at baseline, before alanine aminotransferase (ALT) peak, ALT peak, and after ALT peak, respectively. Fifty-two subjects who h ad persistently normal serum ALT during follow-up served as controls. A total of 160 HBV DNA samples were amplified by nested polymerase chain reaction (PCR) from sera and were directly sequenced. We then analyze the relationship between HBV evolutionary pattern and specific nucleotide/amino acid variants and acute exacerbation. Results: AE cases had a significantly higher level of serum ALT and HBV DNA than controls at baseline. Baseline genetic distance was statistically lower in cases than in controls at the nucleotide level (9.68*10-3 vs. 11.7*10-3, p=0.031), but no such association was found at ALT peak (12.1*10-3 vs. 13.8*10-3, p=0.329). Among AE cases, the genetic distance was also higher at ALT peak when compare with other time points at marginal statistical significance (12.1*10-3 vs. 10.2 *10-3, p=0.071). After point-by-point screening the nucleotide/amino acid positions in the whole Pol gene region, we have revealed the association between AE and variant types at nucleotide and amino acid positions, nt1080 (OR 0.32, p 0.0288), nt1126 (OR 0.33, p 0.0453), nt1242 (OR 0.34, p 0.0346), nt2619 (OR 0.32, p 0.0433), nt2444 (OR 4.07, p 0.0157), aa17 (OR 0.28, p 0.048), aa46 (OR 4.28, p 0.0116) . Conclusion: Our data suggest no clear evidence for the association between rate of viral divergence and the occurrence of AE. Certain single nucleotide polymorphism may serve as predictive of AE.

並列關鍵字

Chronic HBV infection ； Hepatitis B Virus ； Acute exacerbation(AE) ； ALT ； evolution ； diversity

參考文獻

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B型肝炎病毒polymerase基因區變異與慢性B肝急性發作之相關:縱式研究

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