北臺灣人類免疫缺乏病毒感染者C型肝炎病毒之調查

Abstract

C型肝炎病毒 (hepatitis C virus，HCV) 與人類免疫缺乏病毒 (human immunodeficiency virus，HIV) 的感染途徑相似，主要是經由血液與性行為傳染，且兩者目前皆沒有疫苗可供施打。根據世界衛生組織統計，全球HIV感染者約有3,700萬人，合併HIV/HCV共同感染者約有230萬人，研究也發現HIV/HCV共同感染者易增加肝臟相關疾病死亡率。先前研究發現臺灣男同志 (men who have sex with men，MSM) 族群感染HCV人數有上升趨勢。由於HCV新藥可以治癒9成以上的HCV患者，我們希望能了解這個族群感染HCV的危險因子，進而及早診斷並給予治療。因為HCV之基因型別會影響臨床藥物治療的成效，因此患者感染的HCV基因型別也列入分析。本研究目的為調查北臺灣HIV患者的C型肝炎病毒血清盛行率、感染發生率、基因型別分布及疾病相關因子分析。我們以臺大醫院持續追蹤之愛滋病患者且前一年追蹤HCV抗體陰性為收案對象，於2016年共收集2,371位個案之血液檢體。首先以酵素免疫分析 (ELISA) 進行HCV抗體檢測，抗體檢測陽性者，計算盛行率及感染發生率。抗體陽性者再以Real-Time RT-PCR偵測HCV RNA的病毒量，並利用NS5B PCR與基因定序來判定HCV之基因型別；無法測得病毒量的檢體再以重組免疫墨點分析 (Recombinant Immunoblot Assay，RIBA) 確認是否有HCV感染。2016年北臺灣HIV/HCV共同感染血清盛行率為1.77% (42/2,371)，發生率為18.77每1,000人年(36/1,917.5)。進一步分析風險行為，發現MSM比例高達94.4% (34/36)。在單變項分析中以巢式病例對照研究分析發現，在HCV感染前已感染梅毒 (p<0.001) 或近期梅毒血清效價 (RPR) 4倍上升 (p<0.001)，肝功能指數AST平均值 (p=0.04)、AST＞37U/L (p<0.001)、ALT平均值 (p<0.001) 與ALT＞41U/L (p<0.001) 皆與HCV感染具相關性。在多變項分析，則僅有ALT平均值 (p<0.013) 具有統計學上的相關性。ELISA抗體陽性，但未測得病毒量的11個檢體續以RIBA檢測，結果為4個陽性，1個不確定 (Borderline) 及6個陰性。為了解HCV急性感染的比例，我們篩選CD4小於200 cells/uL或ALT>41 U/L的300件ELISA抗體陰性檢體進行混合核酸篩檢，共找出3位急性感染者。因此就研究中測得HCV RNA病毒量共34位患者，其HCV基因型別為HCV-2a (17例，50%)，HCV-6a (9例，26%)、HCV-1b (5例，15%)、HCV-1a (2例，6%) 及HCV-3a (1例，3%)。基因親緣關係樹圖分析 (Phylogenic analysis) 發現共有六個HCV病毒群聚 (clusters)，三個為HCV-2a、兩個HCV-6a及一個HCV-1b。此34位HCV RNA 陽性患者其NS5B序列並未偵測到對Sofosbuvir產生抗藥性的基因突變。總結以上資料，建議應加強高風險族群的定期HCV抗體篩檢，並加做HCV RNA檢測，以及早診斷HCV感染，並給予適當的治療。

Hepatitis C virus (HCV) shares the similar transmission routes, that is body fluid and sexual contacts, with human immunodeficiency virus (HIV), and no vaccine can prevent their infection currently. According to World Health Organization (WHO), there are 37 million people infected with HIV globally, and among which, 2.3 million are HIV/HCV co-infected patients. HIV/HCV co-infection was shown to have higher risks of liver-related mortality. Previously, an increasing trend of HCV infection was observed among HIV-1 infected men who have sex with men (MSM). Therefore, it is critical to identify the risk factors associated with HCV infection in HIV-infected population, in the hope to early identify these patients for clinical treatment. Since the HCV genotypes will influence the selection of direct-acting antiviral agent (DAA) for HCV infection, the HCV genotypes in study subjects will also be determined. The aim of our study is to investigate the HCV seroprevalence, incidence, genotype distribution and risk factors for HCV infection in HIV patients in northern Taiwan. A total of 2,371 blood specimens from HIV-1-infected patients who received clinical care at National Taiwan University Hospital (NTUH) and were seronegative for HCV before 2016 were included for analysis. The anti-HCV IgG ELISA kit (Dia. Pro, Italy) was used to determine the HCV prevalence and incidence. The seropositive specimens were further confirmed by detection of HCV RNA viral loads (VL) (COBAS® AmpliPrep HCV Test, v2.0, Roche, USA) and their HCV genotypes by NS5B PCR and sequencing. For those HCV seropositive with undetectable HCV VL, a recombinant immunoblot assays (RIBA) kit (Mikrogen Diagnostik, Neureid, Germany) was used to confirm the HCV antibody responses. The HCV seroprevalence and incidence in 2016 are 1.77% (42/2,371) and 18.77 per 1,000 person/year (PY) (36/1,917.5), respectively. 94.4% (34/36) of the coinfected patients are MSM. Baseline syphilis (p＜0.001), 4-fold increase of serum RPR titer (p＜0.001), mean AST level (p=0.04), AST＞37 U/L (p＜0.001), mean ALT level (p＜0.001) and ALT＞41 U/L (p<0.001) were found to be associated factors for HCV seroconverter in a nested case-control study. Only mean ALT value (p<0.013) was associated with HCV seroconverter in the multivariate analysis. Of the 11 patients with undetectable HCV RNA, four were positive, one was borderline and six were negative by RIBA. Three patients with acute HCV infection was identified by pooled PCR screening of 300 ELISA-negative specimens from patients with CD4＜200 cells/uL or ALT＞41 U/L. Of the 34 HCV PCR positive specimens, the most prevalent HCV genotype was genotype 2a (17/34, 50%), followed by genotype 6a (9/34, 26%), genotype 1b (5/34, 15%), genotype 1a (2/34, 6%), and genotype 3a (1/34, 3%). Six HCV transmission clusters were identified by phylogenetic tree analysis, belonging to genotype 2a (3 clusters), 6a (2 clusters) and 1b (1 cluster), respectively. No sofosbuvir resistance-associated mutation S282T was identified in these patients. To sum up, regular screening of HCV antibody or even HCV RNA detection is suggested for the high risk group.