Quasispecies Diversity Is a Major Risk Factor for Vertical Hepatitis C Virus Transmission.

BACKGROUND: Vertical transmission is the major cause of pediatric hepatitis C virus (HCV) infection. The objective of this study was to better understand HCV pathogenesis in pregnant women and provide insights into risk factors and mechanisms involved in vertical transmission. METHODS: Evolutionary dynamics of HCV variant spectra and HCV-specific neutralizing antibody responses were examined using high-throughput sequencing and pseudoparticle-based assays in pregnant women monoinfected with HCV (n = 17) or coinfected with HCV and human immunodeficiency virus (HIV)-1 (n = 15). RESULTS: Overall, statistically significant associations were found between HCV quasispecies diversity, selective pressure exerted on the HCV E2 envelope protein, and neutralizing activity of maternal immunoglobulins. Women with low quasispecies diversity displayed significantly higher mean aspartate aminotransferase and alanine aminotransferase levels throughout pregnancy, but this difference was restricted to monoinfected participants. Low quasispecies diversity and inefficient neutralizing activity were also significantly associated with vertical transmission, but only in the monoinfected group. CONCLUSIONS: These results indicate that maternal neutralizing antibody responses play a role in the prevention of vertical HCV transmission, but not in presence of HIV-1 coinfection, and suggest that the mechanism of vertical transmission may be different between monoinfected and coinfected women. These findings could inform management strategies for the prevention of vertical HCV transmission.

No association between early antiretroviral therapy during pregnancy and plasma levels of angiogenic factors: a cohort study.

BACKGROUND: Early antiretroviral therapy (ART) during pregnancy has dramatically reduced the risk of perinatal HIV transmission. However, studies have shown an association between premature delivery and the use of ART during pregnancy (particularly protease inhibitor (PI)-based therapies), which could be explained by placental dysfunction. The objective of this study was to evaluate the association of ART (class, duration of exposure and time of initiation) with placental function by using angiogenic factors placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) as biomarkers. METHODS: Clinical and biological data from 159 pregnant women living with HIV were analyzed. Levels of each biomarker were measured in the first and second trimester of pregnancy. After logarithmic transformation, we compared these using generalized estimating equations according to (a) the type of ART; (b) the duration of exposure to ART; and (c) the time of initiation of ART. RESULTS: After adjusting for variables such as ethnicity, maternal age, gestational age, body mass index, parity, smoking status, and sex of the fetus, we found no significant association between the class of ART (PI-based or not) and serum concentrations of PlGF or sFlt-1. Furthermore, no significant association was found between biomarker levels and the duration of ART exposure or the timing of ART initiation (pre- or post-conception). CONCLUSIONS: This study suggests that first and second trimester angiogenic factor levels are not significantly associated with ART, regardless of the duration or type (with or without PI). These observations seem reassuring when considering the use of ART during early pregnancy.

Vertical Transmission of Hepatitis C Virus: Variable Transmission Bottleneck and Evidence of Midgestation In Utero Infection.

Hepatitis C virus (HCV) can be transmitted from mother to child during pregnancy and childbirth. However, the timing and precise biological mechanisms that are involved in this process are incompletely understood, as are the determinants that influence transmission of particular HCV variants. Here we report results of a longitudinal assessment of HCV quasispecies diversity and composition in 5 cases of vertical HCV transmission, including 3 women coinfected with human immunodeficiency virus type 1 (HIV-1). The population structure of HCV variant spectra based on E2 envelope gene sequences (nucleotide positions 1491 to 1787), including hypervariable regions 1 and 2, was characterized using next-generation sequencing and median-joining network analysis. Compatible with a loose transmission bottleneck, larger numbers of shared HCV variants were observed in the presence of maternal coinfection. Coalescent Bayesian Markov chain Monte Carlo simulations revealed median times of transmission between 24.9 weeks and 36.1 weeks of gestation, with some confidence intervals ranging into the 1st trimester, considerably earlier than previously thought. Using recombinant autologous HCV pseudoparticles, differences were uncovered in HCV-specific antibody responses between coinfected mothers and mothers infected with HCV alone, in whom generalized absence of neutralization was observed. Finally, shifts in HCV quasispecies composition were seen in children around 1 year of age, compatible with the disappearance of passively transferred maternal immunoglobulins and/or the development of HCV-specific humoral immunity. Taken together, these results provide insights into the timing, dynamics, and biologic mechanisms involved in vertical HCV transmission and inform preventative strategies.IMPORTANCE Although it is well established that hepatitis C virus (HCV) can be transmitted from mother to child, the manner and the moment at which transmission operates have been the subject of conjecture. By carrying out a detailed examination of viral sequences, we showed that transmission could take place comparatively early in pregnancy. In addition, we showed that when the mother also carried human immunodeficiency virus type 1 (HIV-1), many more HCV variants were shared between her and her child, suggesting that the mechanism and/or the route of transmission of HCV differed in the presence of coinfection with HIV-1. These results could explain why cesarean section is ineffective in preventing vertical HCV transmission and guide the development of interventions to avert pediatric HCV infection.

Stigma Management Trajectories in Youth with Perinatally Acquired HIV and Their Families: A Qualitative Perspective.

This study explores how family, secrecy and silence contribute to the adoption of stigma management strategies among youth with perinatally acquired HIV (PAHIV). A qualitative method was used. Eighteen youths with PAHIV aged 13-22 years old took part in a semi-structured interview. An exploratory content analysis was performed. Analyses of interviews allowed identification of two HIV stigma management trajectories, both sensitive to the family context: [1] a consolidation of family ties, which contributes to solidarity in stigma management; and [2] a weakening or dissolution of family ties, which contributes to solitary stigma management strategy. Family conditions that support the children in their efforts to develop active stigma management strategies are described. Children likely to experience weakening or dissolution family ties must build strong bonds in the clinical environment and maintain these into adulthood so as to afford them the support they need.

Health outcomes and the transition experience of HIV-infected adolescents after transfer to adult care in Québec, Canada.

BACKGROUND: Little is known on outcomes after transition to adult care among adolescents with perinatal HIV infection. Though there is data from other chronic pediatric diseases suggesting increased morbidity and mortality following transfer to adult care, this has not well been studied among the first wave of survivors of perinatal HIV infection. The primary objective of this study was to determine outcomes after transition to adult care among a cohort of HIV-infected adolescents in Québec, Canada. Secondary objectives were to document participant experiences with the transition process, identify barriers to successful transition, and potential changes to improve the transition process. METHODS: Clinic records were reviewed to identify all perinatally-infected youth who transitioned from the Centre Maternel et Infantile sur le Sida pediatric HIV clinic (Montreal) at age 18 to an adult care provider between 1999 and 2012. Transitioned patients were contacted using last available patient or parental listed phone number on hospital record, internet based telephone directory, or social media. A standardized questionnaire was administered by telephone or in-person interview, and copies of current medical records obtained from treating physicians. RESULTS: Forty-five patients were transferred between 1999 and 2012, among whom 25 consented to the study, eight were lost to follow-up, eight refused participation, and four were deceased. Overall 76 % of patients remained engaged in care, defined by at least one physician visit within 6 months of the interview. Over 50 % reported difficulty with adherence to their current drug regimens. At one-year post-transfer, there was a decrease in the proportion of patients with CD4 count >500 cells/mm(3) from 64 to 29 %, and a statistically significant decrease in absolute CD4 count (mean 370 vs 524 cells/mm(3), p = 0.04.). The majority (92 %) of participants felt that 18 was too young an age to transfer to adult care, and provided suggestions for improving the transition process. CONCLUSIONS: This group of perinatally-infected youth remained engaged in care after transition, however difficulties with adherence and assuming responsibility for their own care were identified as issues in their post-transition care. The high rate of mortality among them and the changes to their health status post-transition suggest that further work is necessary to document the health outcomes of this group in larger, more diverse cohort settings.

Barriers to health-care and psychological distress among mothers living with HIV in Quebec (Canada).

Health-care providers play a major role in providing good quality care and in preventing psychological distress among mothers living with HIV (MLHIV). The objectives of this study are to explore the impact of health-care services and satisfaction with care providers on psychological distress in MLHIV. One hundred MLHIV were recruited from community and clinical settings in the province of Quebec (Canada). Prevalence estimation of clinical psychological distress and univariate and multivariable logistic regression models were performed to predict clinical psychological distress. Forty-five percent of the participants reported clinical psychological distress. In the multivariable regression, the following variables were significantly associated with psychological distress while controlling for sociodemographic variables: resilience, quality of communication with the care providers, resources, and HIV disclosure concerns. The multivariate results support the key role of personal, structural, and medical resources in understanding psychological distress among MLHIV. Interventions that can support the psychological health of MLHIV are discussed.

Family quality of life in families affected by HIV: the perspective of HIV-positive mothers.

The HIV infection of a family member can impact family quality of life (FQoL). The objectives of this study are to (1) describe patterns of FQoL among mothers living with HIV (MLHIV) and (2) identify key factors associated with FQoL in families affected by HIV. Recruitment took place in HIV-specialized clinics and community organizations. A 100 MLHIV and 67 of their children participated in this study. Mothers were on average 40.8 years old and reported having an average of two dependent children at home (M = 2.1, SD = 1.0). Participating children were 16.2 years old, on average. Half of the children were boys (50.8%). More than half were aware of their mother's positive HIV status (68.2%) and 19.7% were diagnosed with HIV. All HIV-positive children were aware of their status. A latent profile analysis was performed on the five continuous indicators of FQoL, and three main profiles of self-reported FQoL among MLHIV were established: high FQoL (33%), moderate FQoL (58%), and low FQoL (9%). Among the mothers' characteristics, education, physical functioning, social support, and resilience increased FQoL, while anxiety and irritability decreased FQoL. Among the children's characteristics, resilience followed the FQoL profile. A trend was observed toward children's greater awareness of the mother's HIV status in high and low FQoL profiles. Additionally, irritability tended to be higher within the lower FQoL profile. FQoL profiles can be used to identify families needing special care, particularly for family interventions with both parents and children. Other relevant indicators must be studied (e.g., closeness and support between family members, availability and accessibility of care, family structure, father-child relationships, and medical condition of the mother) and longitudinal research conducted to estimate the direction of causality between FQoL profile and individual family member characteristics.

Impact of maternal HIV-1 viremia on lymphocyte subsets among HIV-exposed uninfected infants: protective mechanism or immunodeficiency.

BACKGROUND: Reports of increased morbidity and mortality from infectious diseases among HIV Exposed Uninfected (HEU) infants have raised concern about a possible underlying immunodeficiency among them. The objective of this study was to assess the immunological profile of HEU infants born to mothers exhibiting different levels of HIV-1 viremia at the time of delivery. METHODS: Study subjects were enrolled in the Centre maternel et infantile sur le SIDA (CMIS) mother-child cohort between 1997 and 2010 (n =585). Infant CD4+ T cell, CD8+ T cell and CD19+ B cell counts were assessed at 2 and 6 months of age, and compared among HEU infants in groups defined by maternal viral load (VL) at the time of delivery (VL < 50 copies/ml, VL 50-1000 copies/ml, and VL > 1000 copies/ml) in a multivariable analysis. RESULTS: At 2 months of age, infants born to mothers with VL > 1000 copies/ml had lower CD4+ T cell counts compared to those born to mothers with VL < 50 copies/ml at the time of delivery (44.3% versus 48.3%, p = 0.007, and 2884 vs. 2432 cells/mm3, p = 0.02). These differences remained significant after adjusting for maternal and infant antiretroviral drug use, gender, race and gestational age, and persisted at 6 months of age. There were no differences in CD8+ T cell count or absolute CD19+ B cell count between groups, though higher CD19+ B cell percentage was seen among infants born to mothers with VL > 1000 copies/ml. CONCLUSIONS: These results suggest that exposure to high levels of HIV-1 viremia in utero, even in the absence of perinatal transmission, may affect the infant's developing immune system. While further work needs to be done to confirm these findings, they reinforce the need for optimal treatment of HIV infected pregnant women, and careful follow-up of HEU infants.

Novel HIV-1 recombinant forms in antenatal cohort, Montreal, Quebec, Canada.

Near full-length genomes of 4 unclassified HIV-1 variants infecting patients enrolled in an antenatal cohort in Canada were obtained by sequencing. All 4 variants showed original recombination profiles, including A1/A2/J, A1/D, and A1/G/J/CRF11_cpx structures. Identification of these variants highlights the growing prevalence of unique recombinant forms of HIV-1 in North America.

Romantic relationships and sexual activities of the first generation of youth living with HIV since birth.

HIV-infected children, now maturing into adolescence and adulthood, must cope not only with adolescent developmental issues, but also with a chronic, socially stigmatised and sexually transmittable illness. Little research on this first generation of survivors has focused on romantic involvement and sexuality. This study, which employs a mixed-method embedded strategy (qualitative supported by quantitative), describes the perspectives of youth living with HIV since birth concerning: (1) romantic involvement and sexuality; and (2) risk management including the risk of HIV transmission and partner serostatus disclosure. Eighteen adolescents aged 13-22 from Montreal, Canada, participated in individual semi-structured interviews and completed self-report questionnaires. Most youths participated in non-penetrative sexual activities. Ten participants reported having had vaginal and three anal intercourses, at an average age of 14 for girls and 15 for boys. All sexually active youth reported having used a condom at least once. Of those who reported that their first sexual relationship was protected, over half had taken risks in subsequent relationships (e.g., unprotected sex, multiple partners, etc.). Interviews conducted with sexually inactive youths illustrate the interrelatedness of romantic involvement, sexual initiation and potential serostatus disclosure. Involvement in a sexual relationship would not be conceivable unless the partner was informed of their serostatus. For sexually active participants, risk management implies HIV transmission and partner disclosure. These youths have emotional issues regarding disclosure in romantic relationships and few risked potential rejection by disclosing. Condom use acts as a reminder of the infection and a barrier to intimacy. The narratives illustrate how risk perception changes and becomes relative with time and experience, especially when the viral load is undetectable and when past experience has convinced the adolescent that his/her partner might not become infected. Findings reinforce the need to prioritise sexual health issues for young people with perinatally acquired HIV.

HCV quasispecies evolution during treatment with interferon alfa-2b and ribavirin in two children coinfected with HCV and HIV-1.

Two children who acquired hepatitis C virus (HCV) and human immunodeficiency virus type 1 (HIV-1) infection by mother-to-child transmission were monitored during interferon alfa-2b and ribavirin treatment. In Patient C1, CD4(+) T cell counts were within normal range and HIV-1 viral load was undetectable. HCV viral load declined slightly following treatment initiation while novel variants rapidly emerged, indicative of quasispecies diversification. In Patient C2, CD4(+) T cell counts were low and HIV-1 replication was not fully controlled by antiretroviral therapy. HCV viral load rose during treatment and a striking conservation of the variant spectrum was observed. In both cases, there was no decline in quasispecies complexity following treatment initiation and sustained virological response was not achieved. These results suggest that reduction in quasispecies complexity, which is observed in adult responders following interferon treatment, may be mechanistically unrelated with evolution of the variant profile and/or selective pressure exerted on HCV.

Subtle differences in selective pressures applied on the envelope gene of HIV-1 in pregnant versus non-pregnant women.

Pregnancy is associated with modulations of maternal immunity that contribute to foeto-maternal tolerance. To understand whether and how these alterations impact antiviral immunity, a detailed cross-sectional analysis of selective pressures exerted on HIV-1 envelope amino-acid sequences was performed in a group of pregnant (n = 32) and non-pregnant (n = 44) HIV-infected women in absence of treatment with antiretroviral therapy (ART). Independent of HIV-1 subtype, p-distance, dN and dS were all strongly correlated with one another but were not significantly different in pregnant as compared to non-pregnant patients. Differential levels of selective pressure applied on different Env subdomains displayed similar yet non-identical patterns between the two groups, with pressure applied on C1 being significantly lower in constant regions C1 and C2 than in V1, V2, V3 and C3. To draw a general picture of the selection applied on the envelope and compensate for inter-individual variations, we performed a binomial test on selection frequency data pooled from pregnant and non-pregnant women. This analysis uncovered 42 positions, present in both groups, exhibiting statistically-significant frequency of selection that invariably mapped to the surface of the Env protein, with the great majority located within epitopes recognized by Env-specific antibodies or sites associated with the development of cross-reactive neutralizing activity. The median frequency of occurrence of positive selection per site was significantly lower in pregnant versus non-pregnant women. Furthermore, examination of the distribution of positively selected sites using a hypergeometric test revealed that only 2 positions (D137 and S142) significantly differed between the 2 groups. Taken together, these result indicate that pregnancy is associated with subtle yet distinctive changes in selective pressures exerted on the HIV-1 Env protein that are compatible with transient modulations of maternal immunity.

Immunogenicity and Safety of the Quadrivalent Human Papillomavirus Vaccine in Girls Living With HIV.

We evaluated quadrivalent human papillomavirus vaccine seroresponses among 35 girls living with HIV (9-13 years of ages) and compared with data on girls without HIV, as part of a subgroup analysis. The quadrivalent human papillomavirus vaccine was safe and well tolerated. However, antibody response was significantly lower in girls living with HIV relative to girls without HIV. HIV virologic suppression predicted better antibody response.

Predictive value of interleukin-7 levels for virological response to treatment in HIV-1-infected children.

We recently reported that interleukin-7 (IL-7), a potent stimulator of lymphopoiesis, is an independent predictor of virological response to antiretroviral therapy (ART) in HIV-1 infected adults. To determine if this cytokine also predicts treatment response in HIV-1-infected children, a longitudinal study was performed over 48 weeks in 36 treatment-naïve children vertically infected with HIV-1. Subjects who received treatment (n = 29) were stratified as complete virological responders (n = 12), partial virological responders (n = 11), or non-responders (n = 6), based on decline in viral load from baseline to week 48. Median plasma IL-7 levels at baseline were higher in complete responders (4.85 pg/mL, interquartile range [IQR] = 3.35-6.5) than in untreated controls (2.10 pg/mL, IQR = 1.50-3.50; p = 0.05). Linear regression analysis showed that baseline IL-7 levels were positively correlated with changes in HIV-1 viral load between baseline and week 24 (r = 0.40; p = 0.03) and between baseline and week 48 (r = 0.34; p = 0.07), but not with corresponding changes in CD4+ T-cell percentages and absolute counts. Collectively, these results indicate that IL-7 levels at baseline are predictive of virological but not immunological response to ART in children infected with HIV-1.

Evolution and treatment of childhood chronic inflammatory polyneuropathy.

Chronic inflammatory demyelinating polyneuropathy is a rare disease in pediatric patients. The disease usually responds well to standard therapies including immunoglobulins, corticosteroids, and plasmapheresis. However, a minority of cases appear refractory to standard treatments. This report presents the evolution of 13 patients with chronic inflammatory demyelinating polyneuropathy monitored in our pediatric neurology clinic between 1975 and 2005, including two recent patients with refractory diseases. The literature regarding treatment of refractory cases in adults and children is also reviewed.

[Maternal immunity and mother-to-child transmission of HCV and HIV-1: challenges and recent advances]. / Immunité maternelle et transmission mère-enfant du VIH et du VHC : Progrès récents et nouveaux défis.

Human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) are two viral pathogens that establish chronic infections in their hosts and that are at present responsible for serious public health problems on a pandemic scale. HIV-1 and HCV can be transmitted from person to person by contact with bodily fluids. Both can also be transmitted from mother to child during the course of pregnancy and childbirth. There are currently no vaccines available to immunize against HIV-1 and HCV infection or to prevent mother-to-child transmission (MTCT), and accessible treatments have significant yet limited efficacy. However, important progresses have been made since the discovery of HCV and HIV-1 : (a) sensitive screening and detection methods have been perfected ; (b) risk factors for acquisition, replicative cycles, pathogenesis, and mechanisms of transmission have been better characterized ; (c) specific treatments, immunotherapy, and antiretroviral prophylaxis regimen were developed ; (d) immune correlates of protection are better understood ; and (e) vaccine design was undertaken. In addition, co-infection with HCV and HIV-1, which is common among high-risk groups including injection drug users, significantly increases the incidence of MTCT of both viruses. The mechanisms by which this facilitation occurs are still under investigation and may involve direct replicative facilitation, enhancement of placental transfer, and/or interference with host immune responses. Taken together, these developments could lead to the implementation of global scale strategies to prevent MTCT of HCV and HIV-1.

Management and treatment of hepatitis C virus in patients with HIV and hepatitis C virus coinfection: A practical guide for health care professionals.

Concomitant HIV and hepatitis C virus (HCV) is a common yet complex coinfection. The present document is a practical guide for treating HCV infection in people coinfected with HIV. Effective antiretroviral therapies have prolonged survival rates for HIV-infected people over the past decade, which have made latent complications of HCV major causes of morbidity and mortality in these patients. Advances in the treatment of HCV (eg, combined pegylated interferon and ribavirin) offer the possibility of eradicating HCV infection in coinfected persons. The treatment of HCV must be considered in all cases. Intensive management of the adverse effects of HCV treatment is one of the factors for the success of these therapies. HCV eradication is predicted to decrease the mortality associated with coinfection and reduce the toxicity of HIV treatment.

Safety of combination antiretroviral prophylaxis in high-risk HIV-exposed newborns: a retrospective review of the Canadian experience.

INTRODUCTION: The optimal management of infants born to HIV-positive mothers who are untreated or have detectable viral load prior to delivery remains controversial. Despite the increasing use of combination antiretroviral therapy (cART) for post-exposure prophylaxis (PEP) of neonates at high risk of HIV infection, there is little safety and pharmacokinetic data to support this approach. The objective of this study was to evaluate the safety and tolerability of cART for PEP in HIV-exposed neonates. METHODS: Retrospective study on 148 cART and 145 Zidovudine (ZDV) monotherapy-exposed infants identified from four Canadian centres where cART for PEP has routinely been prescribed in high-risk situations. Physician-reported adverse events and clinical outcomes were extracted by chart review. Haematological and growth parameters at birth, one and six months of age were compared between cART and ZDV-exposed infants using multivariate mixed effects modelling. RESULTS: Non-specific signs and symptoms were reported in 10.2% of cART recipients versus none of the ZDV recipients. Treatment was discontinued prematurely in 9.5% of cART recipients versus 2.1% of ZDV recipients (p=0.01). In the multivariate model, cART recipients had lower mean haemoglobin (decrease of 2.07 g/L) over the 6-month period compared with ZDV recipients (p=0.04), but no effect was seen on absolute neutrophil count. cART recipients had lower weight and smaller head circumference at birth and one month of age compared with ZDV-exposed infants; these differences were no longer significant at six months of age. CONCLUSIONS: cART administered at treatment doses for PEP in neonates was generally well tolerated, though a higher incidence of non-specific signs and symptoms and early treatment discontinuation occurred among cART recipients.

HIV viral suppression results in higher antibody responses in HIV-positive women vaccinated with the quadrivalent human papillomavirus vaccine.

OBJECTIVE: To evaluate the immunogenicity and safety of the quadrivalent HPV (qHPV) vaccine in HIV-positive women over 24months. DESIGN: Between November 2008 and December 2012, 372 women aged 15 and older were enrolled from 14 Canadian HIV outpatient clinics in an open label cohort study. The qHPV vaccine (0.5mL) was administered intramuscularly at months 0, 2 and 6. The primary study endpoint was seroconversion to any of the HPV types targeted by the qHPV vaccine. Antibody levels were measured at 0, 2, 7, 12, 18, and 24months. Adverse events were recorded throughout. RESULTS: Of 372 participants enrolled, 310 (83%) received at least one dose of the qHPV vaccine and 277 (74%) received all three doses. Ninety-five percent (293/308) were seronegative for at least one vaccine type at baseline. The median age was 38years (IQR 32-45, range 15-66), 36% were white, 44% black and 13% were of Indigenous origin. Seventy-two percent of participants had a suppressed HIV viral load (VL<40c/ml) at baseline, with a median CD4 count of 510cells/mm(3) (376-695). Month 7 HPV type-specific seroconversion rates were 99.0%, 98.7%, 98.1% and 93.6% for HPV types 6, 11, 16 and 18 respectively in the per-protocol population. Participants with suppressed HIV VL at first vaccine had a 1.74-3.05fold higher peak antibody response compared to those without (p from 0.006 to <0.0001). CONCLUSIONS: This study is the first to examine the qHPV vaccine in HIV-positive women out to 24months and the first to include HIV-positive women through to age 66. The qHPV vaccine was well tolerated, and highly immunogenic. As women with suppressed viral load had higher antibody responses, planning HPV vaccination to occur when persons are virologically suppressed would be optimal for maximizing immune response. Findings provide strong evidence that older HIV-positive women can still benefit from HPV vaccination. CLINICAL TRIAL REGISTRATION: http://www.isrctn.com/ISRCTN33674451.

Characterization of humoral and cell-mediated immune responses directed against hepatitis C virus F protein in subjects co-infected with hepatitis C virus and HIV-1.

BACKGROUND: Hepatitis C virus (HCV) F protein is encoded in an alternate reading frame overlapping the core protein region. Its precise sequence, biological function and mode of expression are currently unclear. This study was conducted to examine the prevalence and characteristics of host humoral and cell-mediated immune responses directed against F protein in patients co-infected with HCV and HIV-1. METHODS: Mutations were introduced to allow the expression of HCV-1a F protein in the absence of core. This recombinant and a truncated form lacking the first 11 amino acid residues shared with core were expressed in Escherichia coli, and their amino acid sequences were verified by mass spectrometry. Vaccinia-F protein recombinants were used to test F protein-specific cytotoxic T lymphocyte (CTL) activity. The binding of F protein-derived peptides to HLA-A*0201 was studied to identify putative CTL epitopes. RESULTS: Sera from 23 of 39 patients infected with various HCV genotypes recognized the truncated form, including 13 of 25 subjects co-infected with HIV-1, indicative of antigenic crossreactivity and consistent with the conservation of F protein coding sequences between HCV genotypes. Crossreactive F protein-specific CTL precursors were detected in nine of 11 HCV-infected subjects, including seven of nine patients co-infected with HCV and HIV-1. Finally, three novel putative HLA-A*0201-restricted CTL epitopes were identified. CONCLUSION: These results indicate that patients co-infected with HCV and HIV-1 can mount immunoglobulin and CTL responses directed against HCV F protein that are fully comparable in scope and magnitude with those observed in individuals infected with HCV alone.