Why some unvaccinated sex partners do not get infected - a possible explanation

StephenW

http://www.medscape.com/viewarticle/736821
为什么一些未接种疫苗的的性伴侣不被感染 - 一个可能的解释.
From Journal of Viral HepatitisHBV-specific T-cell Responses in Healthy Seronegative Sexual Partners of Patients with Chronic HBV Infection

J. Wiegand; S. Meya; V. Schlaphoff; M. P. Manns; J. Mössner; H. Wedemeyer; H. L. Tillmann

Posted: 02/27/2011; J Viral Hepat. 2010;17(9):631-639. © 2010 Blackwell Publishing

从病毒性肝炎杂志
HBV特异性T细胞的反应，在健康的血清阴性慢性乙肝病毒感染患者的性伙伴，

J.韦根; S. Meya;V Schlaphoff; MP曼斯，J. Mössner; H ·魏德迈;Tillmann HL



发表于：2011年2月27日，J病毒Hepat。 2010，17（9）:631- 639。 ©2010布莱克韦尔出版.

Abstract

The hepatitis B virus (HBV) is frequently transmitted by sexual intercourse. Thus, HBV-guidelines recommend vaccination. However, we have identified healthy hepatitis B surface antigen and anti-HBc-negative unvaccinated sexual partners of patients with chronic hepatitis B. We investigated whether HBV-specific cellular immune responses were present that could explain the apparent protection against HBV infection. In six anti-HBc-negative HBV-exposed sexual partners, HBV-specific T-cell responses were studied by proliferation assay and cytometric bead array after stimulation with 74 overlapping peptides spanning the HBV core, pre-S and S-encoding regions. Eleven HBV-unexposed individuals served as negative controls. HBV-DNA was undetectable in serum and peripheral blood mononuclear cells in all cases. HBV-specific cytokine secretion was observed in 4/6 seronegative partners, but only in 1/11 controls. Proliferative responses were detectable in 5/6 partners and 0/11 controls. HBV-specific cytokine secretion exists in healthy seronegative virus-exposed individuals. HBV core-directed immune responses indicate past, but controlled viral replication. T-cell immunity may prevent clinical manifestation of HBV infection in the absence of humoral immunity.

摘要

B型肝炎病毒（HBV）是经常通过性交传染。因此，乙肝病毒的指引建议的疫苗接种。然而，我们已经确定了健康的乙肝表面抗原和抗- HBc阴性未接种疫苗的慢性乙型肝炎患者，我们调查是否HBV特异性细胞免疫反应，目前能够解释明显的抗HBV感染的保护性的合作伙伴。在6个抗- HBc阴性乙肝病毒暴露性伴侣，HBV特异性T细胞的反应进行了研究增殖实验和跨越74个重叠肽乙肝病毒核心，前S和S -编码区域刺激后式微珠阵列。十一乙肝病毒未公开的个人作为阴性对照。 HBV - DNA检测不到血清和外周血单核细胞，在所有的情况下。 HBV特异性细胞因子的分泌，观察4 / 6的血清阴性的合作伙伴，但只在1/11控制。增殖反应检测，5 / 6的合作伙伴和1 /11控制。 HBV特异性细胞因子的分泌存在于健康的血清阴性的病毒暴露个体。 HBV核心导向的免疫反应表明，过去，但控制病毒复制。 T细胞免疫，体液免疫的情况下可以防止乙肝病毒感染的临床表现。

StephenW

Introduction

The hepatitis B virus (HBV) is one of the most infectious viruses with frequent sexual transmission. Unprotected sexual intercourse is associated with an estimated risk of infection of at least 20%.[1] The incidence of HBV infection rises after the onset of sexual activity in puberty and peaks in the age group of 25–29 years.[2] Overall, sexual transmission is the most frequent mode of infection in Germany and accounts for 34% of cases. Importantly, it is associated with the lack of pre-emptive vaccination.[2] Thus, recent HBV-guidelines strongly recommend vaccination of sexual partners to prevent infection.[3–5] Vaccination with recombinant hepatitis B surface antigen (HBsAg) induces a humoral immune response with generation of antibodies against HBsAg (anti-HBs). An anti-HBs >10 IU/mL is believed to protect from HBV infection.[6] However, there are healthy seronegative sexual partners of patients with chronic hepatitis B who have never been vaccinated, but are negative for HBsAg, anti-HBs, anti-HBc (antibodies against hepatitis B core protein) and HBV-DNA. Thus, the present study investigated whether such healthy, but HBV-exposed subjects without any virus-specific humoral immune response show HBV-specific cellular immune responses possibly explaining the absence of signs of HBV infection.

In hepatitis C, virus-specific T-cell responses could be detected in exposed seronegative family members,[7] in healthy individuals after occupational exposure.[8,9] or in seronegative drug users.[10,11] Hepatitis C virus (HCV)-specific CD4+ and CD8+ lymphocytes were detected at low and sometimes at transient levels, but indicated an immunological memory after subclinical infection presumably providing antiviral protection by prompt HCV-specific effector function in vivo. Similar T-cell responses were observed in homosexual and heterosexual seronegative partners of HIV-infected individuals or seronegative HIV-exposed health care workers.[12–14]

The present study aimed to investigate HBV-specific T-cell responses by usage of overlapping HBV-related peptides spanning the HBV core, pre-S, and S encoding regions to study a large number of potential epitopes and facilitate a comprehensive screening of TH1 and TH2 cytokine secretion. The results showed HBV-specific TH1 cytokine secretion and hepatitis B core-directed immune responses indicating past, but controlled viral replication in healthy seronegative HBV-exposed individuals.

简介

B型肝炎病毒（HBV）是传染性最强的病毒之一，频繁的性传播。无保护的性交，估计至少有20％的感染风险。[1]性活动在青春期和高峰在25-29岁年龄组发病后乙肝病毒感染的发病率上升。[2]总体性传播是感染最常见的模式，34％的情况下在德国和帐户。重要的是，缺乏先发制人的疫苗接种相关。[2]因此，最近的乙肝病毒的指引强烈建议性伴侣接种疫苗，以防止感染。[3-5]与疫苗接种重组乙肝表面抗原（HBsAg）的诱导体液免疫反应，产生对乙肝表面抗原抗体（抗- HBs）。一个抗- HBs> 10 IU / mL的是相信，以保护乙肝病毒感染。[6]不过，也有从未接种疫苗的慢性乙型肝炎患者的血清阴性的健康性伴侣，但HBsAg，抗- HBs的负面，抗- HBc（抗B型肝炎核心蛋白抗体）和HBV - DNA。因此，本研究调查是否健康，但乙肝病毒暴露的科目没有任何病毒的特异性体液免疫反应表明HBV特异性细胞免疫反应，可能解释了乙肝病毒感染的迹象的情况下。

暴露血清阴性家庭成员可以在检测丙型肝炎病毒特异性T细胞反应[7]在健康的个体职业暴露后[8,9]或血清阴性吸毒者。[10,11]丙型肝炎病毒（ HCV）特异性的CD4 +和CD8 +淋巴细胞检测低，有时，在瞬态水平，但表示有隐性感染可能提示丙型肝炎病毒在体内的具体效应功能提供抗病毒药物保护后的免疫记忆。类似的T细胞反应进行观察，在同性恋和异性恋的艾滋病毒感染者或血清阴性血清阴性伙伴艾滋病毒暴露的医护工作者。[12-14]

本研究旨在探讨使用重叠HBV相关肽跨越HBV核心，前S，和S编码区，研究了大量潜在的抗原表位，并促进Th1型全面的检查和HBV特异性T细胞反应Th2细胞因子的分泌。结果表明HBV特异性Th1细胞因子的分泌和乙肝核心的免疫反应，说明过去，但病毒复制控制在健康的血清阴性乙肝病毒暴露的人。

StephenW

Materials and Methods材料和方法http://www.medscape.com/viewarticle/736821_2

Results结果http://www.medscape.com/viewarticle/736821_3

Discussion

Virus-specific T-cell responses have been described in seronegative partners after sexual contact with HIV-infected individuals (5/5 with homosexual intercourse, 3/6 with heterosexual intercourse), in occupationally HCV-exposed (n = 5/10) or in HIV- exposed (n = 6/8) health care workers and in seronegative intravenous drug abusers (46–58% of cases).[8–14] We hypothesized that virus-specific T-cell responses may be even more frequent in seronegative sexual partners of patients with chronic hepatitis B because HBV is considered to be much more infectious than HCV and HIV with high risk of transmission in the absence of HBV-specific humoral immunity, i.e. after missing or ineffective HBV vaccination. All tested sexual partners were negative for HBsAg, anti-HBs or anti-HBc in serum.

HBV-DNA was measured with a highly sensitive PCR assay and could not be detected either in serum or in PBMC in all individuals. However, HBV-specific T-cell responses and virus-induced TH1 cytokine secretion indicated past, but controlled viral replication.

It may be speculated that the healthy sexual partners have either undergone subclinical, but completely resolved HBV infection in the past with resulting long-lasting T-cell memory possibly preventing re-infection or that these individuals harbour seronegative occult HBV replication which continuously stimulates the cellular immune system, but which is also controlled by T-cell immunity.

Seronegative occult HBV infection is defined by presence of HBV-DNA in the liver or in PBMC in the absence of HBsAg, anti-HBc and anti-HBs in serum.[18,19] However, we could not investigate hepatic tissue for HBV-DNA replication, because it was unethical to perform liver biopsies in individuals without hepatic disease.

The single measurement of HBV-DNA in serum and in PBMC at study entry may not exclude minimal levels of replicating virus, because fluctuating HBV-DNA levels can be observed both in serum and in PBMC with repetitive experiments after resolution of acute HBV infection.[20–22] However, even during clinical follow-up, no evidence of hepatitis could be detected in the exposed sexual partners assuming that active relevant infection had not occurred.

Analysis of the proliferation assay revealed multispecific T-cell responses in five of six investigated individuals. They were directed against different HBV epitopes with a predominance of HBV core antigen-specific sequences. Recent data in occult HBV infection could detect virus-specific T-cell expansion only in anti-HBc positive patients, but not in seronegative cases.[23] The Italian individuals were all infected with chronic hepatitis C, which leads the authors to the idea, that control of HBV replication in occult seronegative HBV infection was either mainly facilitated by the innate immune system or by the interference of hepatitis C viral proteins with the hepatitis B virus. Our results indicate the presence of an HBV-specific adaptive immune response in seronegative individuals, especially because virus-specific T-cell responses or cytokine secretion could not be observed in negative controls. Moreover, the observation that proliferative responses increased after vaccination indicates that the cellular immune system of the healthy sexual partners has a memory function with cross-reactivity between different epitopes, because both core and pre-S responses emerged, even though these epitopes are absent in the vaccines used. Epitope spreading with increasing CD8+ T-cell responses has been observed i.e. in mice after single-epitope DNA vaccination against LCMV infection.[24]Thus, it may be speculated that the underlying chronic hepatitis C infection may have impaired the cellular immune response in the Italian study. However, this theory does not exclude the possibility that the innate immune system is of crucial relevance in the control of subclinical HBV infection in both study cohorts.

The observed proliferative responses were mostly weak and fluctuating between different time points. The strength of the cellular immunity resembles previous results of our group in hepatitis C patients who cleared low levels of HCV viremia in the absence of a strong adaptive immune response which might be an explanation for low rates of HCV seroconversion after occupational exposure.[25] The quality of proliferative responses can be compared to observations after resolution of acute HBV infection.[20,21,26–28] The HBV core-protein harbours the most frequently recognized epitopes both in our patients, in self-limited acute and in occult HBV infection.[21,23,27,28] Thus, HBV core directed T cells may be most important for the successful prevention of clinical symptoms in the investigated healthy seronegative sexual partners.

Although we could not perform FACS-analysis in the present patient cohort, it is tempting to speculate that their HBV-specific CD4+ T cells act as effector memory cells. The secreted cytokines showed a TH1-profile with a dominant IFNγ secretion. IFNγ is one of the most important cytokines of the antiviral immune response in acute HBV infection[29,30] and is critically involved in HBV clearance by noncytolytic viral eradication.[31,32] Interestingly, Penna et al. [21] observed a TH1 cytokine profile with IFNγ production in the acute phase of HBV infections, whereas in the recovery phase the cytokine pattern switched to a TH0-profile with detection of IFNγ, IL-4 and IL-5. In our experiments, we could only measure IL-10 as member of the TH2 cytokine family, which, however, was undetectable in all seronegative sexual partners. Thus, the status of our investigated individuals may not just be a single acute HBV infection, but the result of repetitive exposure leading to subclinical infections caused by ongoing unprotected sexual intercourse with chronically HBV infected patients.

Our study is limited by several restrictions: (i) The number of studied individuals is small, (ii) a thorough characterization of HBV-specific T- cell responses with FACS analysis or intracellular cytokine staining could not be performed in this pilot project, (iii) the use of overlapping peptides may facilitate stimulation not only of HBV-specific CD4+, but also of CD8+ T cells in the proliferation assay which does not allow differentiation of both cell types without the mentioned additional immunological techniques, (iv) the observed HBV-specific cellular immune responses were weak and fluctuating, however, positive reactions of control antigen and absence of virus-specific reactions in the healthy control group indicate HBV-induced T-cell immunity.

In conclusion, our investigations provide the first basic evidence that HBV-specific T-cell responses can be observed in healthy seronegative sexual partners of patients with chronic HBV infection. It is tempting to further specify these results in the future, because the cellular immune system may prevent acute HBV episodes after unprotected sexual intercourse in the absence of humoral immunity. However, because the antiviral efficacy of the HBV-specific T-cells is not finally proven, vaccination of exposed individuals and use of condoms must stay the standard of care to reliably prevent transmission of the disease.

StephenW

讨论

病毒特异性T细胞的反应已经在性接触后，与艾滋病毒感染者（5 / 5同性恋性交，异性性交3 / 6），在职业的HCV暴露组（n = 5 / 10），或血清阴性的合作伙伴在艾滋病毒暴露（N = 6 / 8）卫生保健工作者和血清阴性的静脉吸毒者（46-58％的病例）[8-14]，我们推测，病毒特异性T细胞的反应可能会更加频繁。因为乙肝病毒被认为是高风险的传播丢失或无效的乙肝疫苗后，即在HBV特异性体液免疫的情况下，更比丙型肝炎病毒和艾滋病毒感染血清学阴性的慢性乙型肝炎患者的性伴侣。所有测试性伴侣为HBsAg，抗- HBs阳性或血清中的抗- HBc均为阴性。

具有高度灵敏的PCR检测HBV - DNA的测定，无法检测到的所有个人，无论是在血清或PBMC中。然而，HBV特异性T细胞反应和病毒诱导Th1细胞因子分泌表示过去，但控制病毒复制。

可推测，健康的性伙伴或者发生亚临床，但在过去彻底解决可能防止再感染造成长期的T细胞内存或这些人海港血清阴性的隐匿性乙肝病毒复制不断刺激细胞HBV感染免疫系统，但也控制T细胞免疫。

血清阴性的隐匿性乙肝病毒感染是指HBsAg，抗- HBc和抗- HBs在血清的情况下在肝脏或PBMC中HBV - DNA的存在[18,19]但是，我们无法调查肝组织的HBV - DNA复制，因为它是不道德的执行无肝脏疾病的个人的肝活检。

血清中和PBMC中的HBV - DNA的研究开始时的单一测量，可能不排除复制病毒的最低水平，可重复的实验观察，因为波动的HBV - DNA的水平，血清和PBMC中急性HBV感染的决议后。[ 20-22]然而，即使在临床跟进，没有肝炎的证据，可在暴露的性伴侣，假设活动有关的感染检测没有发生。

增殖实验分析显示，在五六个调查个人multispecific的T细胞反应。他们针对不同的乙肝病毒抗原表位与HBV核心抗原特异性序列为主。隐匿性乙肝病毒感染的最新数据，仅在检测抗- HBc阳性患者病毒特异性T细胞扩增，但不是在血清阴性的情况下[23]意大利人都感染与慢性丙型肝炎，这导致作者的想法，隐匿性血清阴性的HBV感染，HBV复制控制主要是促进先天免疫系统或丙型肝炎病毒蛋白与乙肝病毒的干扰。我们的研究结果表明HBV特异性的适应性免疫反应在血清阴性个体存在，特别是因为病毒特异性T细胞反应或细胞因子的分泌无法在阴性对照观察。此外，增殖反应，增加疫苗接种后的观察结果显示，细胞的免疫系统健康的性伙伴有不同表位之间的交叉反应的记忆功能，因为核心和前S反应出现，即使没有这些表位使用的疫苗。抗原表位的蔓延增加CD8 + T细胞的反应已被观察到的在小鼠体内，即单一的抗原表位对LCMV感染的DNA疫苗接种后。[24]因此，它可能是推测，在底层慢性肝炎彗星感染可能已受损的细胞在免疫响应意大利的研究。然而，这一理论并不排除这种可能性的先天免疫系统是在两个研究组群的亚临床型HBV感染控制的关键意义。

观察到的增殖反应，大多是弱，在不同的时间点之间波动。细胞免疫的强度类似于本集团以前的结果，在C型肝炎患者清除丙型肝炎病毒血症水平低，缺乏一个强有力的适应性免疫反应，这可能是职业暴露后丙型肝炎病毒血清学转换率较低的解释[25]增殖反应的质量可以观察急性HBV感染后的决议。[20,21,26-28]乙肝病毒核心蛋白港口的公认的最频繁的表位，无论是在我们的病人，在急性自限性和隐匿乙肝病毒感染。[21,23,27,28]因此，HBV核心执导T细胞可能是最重要的成功预防调查健康性伙伴血清阴性的临床症状。

虽然我们无法执行目前病人队列流式细胞仪分析，很容易让人推测，其HBV特异性CD4 + T细胞作为效应记忆细胞的行为。主导IFNγ分泌，分泌的细胞因子显示一个TH1的知名度。 γ干扰素的抗病毒药物在急性HBV感染的免疫反应的最重要的细胞因子之一[29,30]和参与HBV noncytolytic病毒消灭间隙是至关重要。[31,32]有趣的是，彭纳等。 [21]观察Th1细胞因子γ干扰素在乙肝病毒感染的急性期的生产与轮廓，而在复苏阶段，细胞因子的模式切换到TH0中引人注目的检测IFNγ，IL - 4和IL - 5。在我们的实验中，我们只能测量IL - 10作为Th2细胞因子家族的成员，然而，在所有血清阴性性伴侣无法察觉。因此，我们的调查，个人的地位可能不只是一个单一的急性乙肝病毒感染，但与慢性乙型肝炎病毒感染的患者正在进行的未受保护的性交引起的亚临床感染导致的重复曝光。

我们的研究是有限的几个限制：（一）研究个人的数量小，（二）彻底的FACS分析或细胞内细胞因子染色的HBV特异性T细胞反应的表征不能在这个试点项目的执行，（三）使用重叠的肽可能促进刺激HBV特异性CD4不仅+，而且对CD8 + T细胞的增殖检测这并没有让没有的提到额外的免疫学技术的两种类型细胞的分化，（四）在观察乙肝病毒特异性细胞免疫反应疲软和波动，但是，对照抗原和缺乏积极的反应，病毒在健康对照组特定的反应表明HBV诱导T细胞免疫。

总之，我们的调查提供的第一个基本的证据，可以在健康的血清阴性的慢性乙肝病毒感染患者的性​​伴侣观察HBV特异性T细胞反应。进一步明确在未来这些结果是很有诱惑力的，因为细胞的免疫系统可以防止急性乙肝病毒发作后，体液免疫的情况下的无保护的性交。然而，由于HBV特异性T细胞的抗病毒疗效并不最终证明，暴露的人接种疫苗和使用避孕套必须保持可靠地防止疾病传播的护理标准。

咬牙硬挺

晦涩难懂的翻译啊