Hepatitis C virus-specific cell-mediated immune responses in children born to mothers infected with hepatitis C virus.

OBJECTIVE: To investigate the association between hepatitis C virus (HCV)-specific cell-mediated immunity (CMI) responses and viral clearance in children born to mothers infected with HCV. STUDY DESIGN: A cross-sectional study of children from a mother-infant cohort in Egypt were enrolled to detect CMI responses to recombinant core and nonstructural HCV antigens (nonstructural segments NS3, NS4a/b, and NS5 of the HCV genome) using an interferon-gamma enzyme-linked immunospot assay. Children born to mothers with chronic HCV were enrolled into 3 groups: transiently viremic (n = 5), aviremic (n = 36), and positive control (n = 6), which consisted of 1 child with chronic HCV from this cohort and another 5 children with chronic HCV from a companion study. Children without HCV born to mothers without HCV (n = 27) served as a negative control group. Wilcoxon rank sum test was used to compare the magnitude of CMI responses between groups. RESULTS: None of the 6 control children who were positive for HCV responded to any HCV antigen, and 4 (80%) of 5 children with transient viremia responded to at least one HCV antigen, compared with 5 (14%) of 36 and 3 (11%) of 27 children in the aviremic and negative control groups, respectively. Children with transient viremia elicited stronger responses than did negative controls (P = .005), positive controls (P = .011), or children without HCV viremia (P = .012), particularly to nonstructural antigens. CONCLUSIONS: HCV-specific CMI responses were significantly higher in magnitude and frequency among transiently infected children compared with those persistently infected. This suggests CMI responses may be associated with past viral clearance and can identify children at high risk of infection, who can be targeted for health education, screening, and follow-up.

Strong hepatitis C virus (HCV)-specific cell-mediated immune responses in the absence of viremia or antibodies among uninfected siblings of HCV chronically infected children.

BACKGROUND: Cell-mediated immune (CMI) responses to hepatitis C virus (HCV) antigens in adults without seroconversion or viremia are biomarkers for prior transient infection. We investigated HCV-specific CMI responses in seronegative children living with HCV-infected siblings. METHODS: Children 3-18 years of age living with HCV-infected siblings were screened for HCV antibodies and HCV RNA. Peripheral blood mononuclear cells (PBMCs) were evaluated for HCV-specific CMI responses by interferon γ (IFN-γ) enzyme-linked immunospot assay using 3 recombinant HCV protein antigens. Flow cytometry phenotypically characterized IFN-γ-secreting cells. RESULTS: Forty-five seronegative children and 5 seropositive viremic siblings had functionally viable PBMCs. Among the 45 seronegative siblings, 15 (33.3%) had positive HCV-specific IFN-γ responses, and subsequent RNA testing revealed that 3 were viremic. Compared with the 5 seropositive viremic children, the median number of HCV-specific spot-forming units was significantly higher in the 12 seronegative aviremic children (P = .002) and in the 3 seronegative viremic children (P = .025). Flow cytometric analysis revealed that IFN-γ was synthesized mainly by CD4(+) T cells. CONCLUSION: Strong HCV-specific CD4(+) T cell responses were detectable in higher frequency among seronegative, aviremic children compared with persistently infected siblings. Further studies are needed to determine whether these immune responses are protective against HCV infection.

Prospective cohort study of mother-to-infant infection and clearance of hepatitis C in rural Egyptian villages.

Although persistent transmission of hepatitis C virus (HCV) from infected mothers to their infants is reported in 4-8%, transient HCV perinatal infection also occurs. This prospective cohort study determined perinatal HCV infection- and early and late clearance-rates in 1,863 mother-infant pairs in rural Egyptian villages. This study found 15.7% and 10.9% of pregnant women had HCV antibodies (anti-HCV) and HCV-RNA, respectively. Among 329 infants born of these mothers, 33 (10.0%) tested positive for both anti-HCV and HCV-RNA 2 months following birth-29 (12.5%) having HCV-RNA positive mothers and 4 (with transient infections) having mothers with only anti-HCV. Fifteen remained HCV-RNA positive at one and/or 2 years (persistent infections), while 18 cleared both virus and antibody by 1 year (transient infections). Among the 15 persistent cases, 7 cleared their infections by 2 or 3 years. At 2- to 6- and at 10- to 12-month maternally acquired anti-HCV was observed in 80% and 5% of infants, respectively. Four perinatally infected and one transiently infected infant were confirmed to be infected by their mothers by the sequence similarity of their viruses. Viremia was 155-fold greater in mothers of infants with persistent than mothers of infants with transient infections. Maternal-infant transmission of HCV is more frequent than generally reported. However, both early and late clearance of infection frequently occurs and only 15 (4.6%) and 8 (2.4%) infants born of HCV-RNA positive mothers had detectable HCV-RNA at one and 2-3 years of age. Investigating how infants clear infection may provide important information about protective immunity to HCV.

Hepatitis C vaccine: supply and demand.

Despite difficulties associated with extreme variability and mutability of hepatitis C virus (HCV), several vaccines that prevent initial infection or viral persistence, or that clear viraemia in individuals with chronic HCV infections, are currently in development. At least one vaccine that may prevent chronic persistent infections will soon be available for testing. We review the widespread importance of HCV infection and disease, the immune response to HCV and correlates of protection, prevention strategies and vaccine candidates, and groups that will need the vaccine and provide suitable populations for assessing vaccine safety and efficacy. The evaluation of prophylactic vaccines is particularly problematic since distribution must focus upon individuals at high risk of exposure-for example, intravenous drug users and health-care providers in areas with high HCV prevalence. Although there is a huge need for therapeutic vaccines, further immunological hurdles must be cleared before one becomes available.

HIV-positive poor women may stop breast-feeding early to protect their infants from HIV infection although available replacement diets are grossly inadequate.

Little is known about mothers' perspectives and experiences of early breast-feeding cessation as a strategy to reduce postnatal HIV transmission in rural, resource-constrained settings. We conducted in-depth interviews (IDI) with 15 HIV-positive breast-feeding mothers of infants aged 3-5 mo about their plans for feeding their infants after age 6 mo. We also conducted IDI with 12 HIV-positive mothers who intended to stop breast-feeding after receiving their infant's HIV-PCR negative test result at age 6 mo. Twenty-four-hour dietary recalls were conducted with the same 12 mothers and 16 HIV-negative or status unknown mothers who were breast-feeding their 6- to 9-mo-old infants. Of the 12 mothers who intended to stop breast-feeding, 11 did so by 9 mo. Median energy intake (percent requirement) was 1382 kJ (54%) among weaned infants compared with 2234 kJ (87%) among breast-feeding infants. Median intakes were <67% of the recommended levels for 9 and 7 of the 12 micronutrients assessed for weaned and breast-feeding infants, respectively. Factors facilitating early breast-feeding cessation were mothers' knowledge about HIV transmission, family support, and disclosure of their HIV status; food unavailability was the primary barrier. HIV-positive mothers in resource-constrained settings may be so motivated to protect their child from HIV that they stop breast-feeding early even when they cannot provide an adequate replacement diet. As reflected in the new World Health Organization guidance, HIV-positive mothers should continue breastfeeding their infants beyond 6 mo if replacement feeding is still not acceptable, feasible, affordable, sustainable, and safe.

Incidence and risk factors for hepatitis C infection in a cohort of women in rural Egypt.

A prospective cohort study of the incidence and risk factors for hepatitis C virus (HCV) infection was performed in 2171 pregnant women in three rural Egyptian villages who were HCV antibody (anti-HCV) and RNA (HCV-RNA) negative at baseline. During an average of 2.2 years follow up, 25 incident cases were observed, giving an estimated HCV incidence of 5.2/1000 person-years (PY). The infection rate correlated with community anti-HCV prevalence in pregnant women, while the perinatal incidence rate of 11.2/1000 PY was almost five times that of the non-perinatal rate (2.3/1000 PY). The data suggested iatrogenic perinatal risk factors were associated with infection in one village, while health education reduced infections in another. Among the 25 incident cases, eight were HCV-RNA negative when they were first found to be anti-HCV positive and one-third of the 15 viraemic cases with follow-up data available cleared their HCV-RNA after an average of 1.3 years. None of the 25 incident cases were jaundiced or had symptoms of hepatitis but elevated serum alanine aminotransferase levels confirmed hepatitis in nine. Our data suggest that asymptomatic HCV infections frequently occurred during the perinatal period but often cleared and that educating medical personnel on safe practices possibly reduced HCV transmission.

Active surveillance for acute viral hepatitis in rural villages in the Nile Delta.

BACKGROUND: Acute viral hepatitis is less frequent in Egypt than serum antibody levels suggest. Because acute viral hepatitis has a wide clinical spectrum, we tested the hypothesis that many cases are undetected because of mild illness caused by initial, early-childhood exposure to hepatitis viruses. METHODS: During active case detection among 20,000 inhabitants of rural villages in Egypt, we screened 1715 symptomatic patients for serum alanine aminotransferase (ALT) levels. Viral hepatitis markers were tested in 47 subjects who had ALT levels that were least twice the normal level. RESULTS: Of the 47 individuals tested, 4 children aged 3-5 years had immunoglobulin M (IgM) antibodies to hepatitis A virus (anti-HAV IgM). One also had a possible false-positive result to a test for IgM antibodies to hepatitis E virus. None had serological evidence of acute hepatitis B virus (HBV) infection or hepatitis C virus (HCV) infection. However, 33 of the remaining 43 had active HCV infection, having both antibodies to HCV (anti-HCV) and HCV RNA. Four others anti-HCV without HCV RNA, and 2 others had seroconversion to anti-HCV during follow-up. Two patients who were positive for hepatitis B surface antigen had chronic HBV infection. Only 3 with elevated ALT levels had no evidence of acute or chronic infections with known hepatitis viruses. Immunoglobulin G antibodies to hepatitis E virus was detected in 40 patients. CONCLUSION: Active surveillance covering approximately 50,000 person-years detected only 4 cases of acute HAV infection. Almost all persons with mild symptoms and elevated ALT levels had serological evidence of chronic viral hepatitis, most often associated with HCV. Many of these cases were probably "flare-ups" of HCV infection or incidental illness in patients with chronic HCV infection, but some could have been caused by difficult-to-confirm initial HCV infections. Although serological evidence for exposures was highly prevalent, hepatitis viruses seldom caused acute viral hepatitis in these communities.

Transmission of hepatitis C virus between parents and children.

Egyptian children with infected parents are at high risk of infection with hepatitis C (HCV). Analysis of data collected during surveys of rural communities show children whose parents had antibodies to HCV (anti-HCV) were at higher risk for having anti-HCV than children whose parents did not. The association was greater with mothers than fathers and when the parent had HCV RNA. For instance, 87 (14%) of 612 children had anti-HCV whose mothers had HCV RNA compared with 28 (7%) of 401 whose mothers only had anti-HCV and 79 (2.6%) of 3,086 whose mothers were seronegative. These associations persisted after controlling for age, parenteral exposures, and serologic status of the other parent. Sequencing isolates from 13 families with parent(s) and children having HCV RNA showed 10 of 18 had genetically similar viruses. These findings suggest Egyptian children are at high risk of being infected with HCV by their parents and identification of the transmission routes would allow for preventive measures.

Hepatitis E antibody seroconversion without disease in highly endemic rural Egyptian communities.

Hepatitis E virus (HEV) is enterically transmitted and causes self-limiting acute viral hepatitis (AVH) primarily in less developed countries. A prospective cohort study to assess incidence of, and risk factors for, seroconversion to HEV (anti-HEV) was conducted in two Egyptian villages with a 67.7% anti-HEV prevalence. Nine hundred and nineteen villagers who were initially anti-HEV-negative were followed for 10.7 months. Thirty-four (3.7%) had strong anti-HEV serologic responses at follow-up giving an estimated anti-HEV incidence of 41.6/1,000 person-years. No significant associations were found between anti-HEV seroincidence and demographic and socioeconomic factors, source of water, household plumbing or sanitation, hand and vegetable washing, ownership of animals, jaundice and many other variables. None of the seroconverting subjects gave a history compatible with AVH during the interval. We hypothesize that both zoonotic and anthroponotic transmission of avirulent (possibly genotype-3) HEV is occurring extensively in these rural villages. An alternative explanation for the lack of morbidity among anti-HEV incident cases could be initial asymptomatic infections occur during early childhood with subsequent antibody titer boosting without illness upon re-exposure to the virus.

Prevalence of and risk factors for hepatitis C in rural pregnant Egyptian women.

Prevalence and risk factors for hepatitis C virus (HCV) infection were studied in 2,587 pregnant women from three rural Egyptian villages in the Nile Delta being admitted to a prospective cohort study of maternal-infant transmission; 408 (15.8%) had antibodies to HCV (anti-HCV) and 279 (10.8%) also had HCV-RNA. Fewer than 1% gave a history of jaundice or liver disease. Risk factors for anti-HCV included increasing age, low socioeconomic status and a history of blood transfusion or injection therapy for schistosomiasis. Sub-analyses after stratification of subjects by village revealed risks associated with specific venues for medical care, having a previous delivery attended by a traditional birth assistant (TBA), receiving medical care in a temporary clinic located in a mosque, overnight admission to a private doctor's clinic, and circumcision by a TBA or a 'health barber'. Our results suggest HCV causes very little detected illness in young adult Egyptian women and some sources of HCV transmission in rural Egypt in the past were associated with the provision of medical care and varied by location. Prevention should be focused on providing appropriate resources and health education should be given to formal and informal health care providers and should be sufficiently broad to adjust for local variations in exposures.

High prevalence of hepatitis E antibodies in pregnant Egyptian women.

The epidemiology of hepatitis E virus (HEV), an enterically-transmitted cause of acute viral hepatitis (AVH), is not fully understood. During outbreaks on the Indian subcontinent and elsewhere, HEV causes severe AVH with mortality rates around 20% during pregnancy. In Egypt, where prevalence of HEV antibodies (anti-HEV) in rural communities is very high, severe HEV-caused AVH in pregnant women has not been reported. This study examined a cohort of 2,428 pregnant women in the Nile Delta to assess prevalence of, and risk factors for, anti-HEV and correlated these with history of liver disease. Anti-HEV prevalence was 84.3%. Several risk factors associated with anti-HEV included older age, many siblings, not using soap to wash produce and frequent contact with cats. History of jaundice and liver disease was rare and not increased in those having anti-HEV. Our results confirm Egypt's high HEV endemicity and show that almost all women of childbearing age in these communities had prior HEV exposures without a history of liver disease. Reasons for the lack of clinical hepatitis remain unclear but could be the result of early childhood HEV exposures, producing long-lasting immunity and/or modify subsequent responses to exposure. Alternatively, the predominant HEV strain(s) in Egypt are less virulent than those in South Asia.

Estimation of the risk of transmission of hepatitis C between spouses in Egypt based on seroprevalence data.

BACKGROUND: Transmission of hepatitis C virus (HCV) between spouses could be due to sexual contact, sharing needles, or other routes. There is uncertainty regarding the degree to which HCV is transmitted between spouses. METHODS: Data from a 1997 cross-sectional serological survey of HCV in two communities in Egypt were used to estimate the risk of transmission between spouses by simultaneously modelling the probabilities of community acquisition and spousal transmission of HCV as functions of known predictors. RESULTS: We estimate that the probability of wife-to-husband transmission was 34% (95% CI: 15-49%) and 10% (95% CI: 0-26%) for anti-HCV-positive wives with and without detectable HCV RNA, respectively. The probability of husband-to-wife transmission was estimated to be 3% (95% CI: 0-13%) and 0% (95% CI: 0-9%) for husbands with and without detectable HCV RNA, respectively, at the time of the survey. There was moderate evidence that the probability of wife-to-husband transmission differed from that of husband-to-wife transmission (P = 0.076), and there was greater risk of transmission from those with detectable RNA at the time of the survey (P = 0.046). We estimate that 6% of those infected acquired HCV from their spouse. CONCLUSION: Our study results support the possibility that HCV is transmitted between spouses in Egypt. Further research is needed to identify the exact routes of transmission so that preventive measures can be instituted.

Exposure to hepatitis C virus induces cellular immune responses without detectable viremia or seroconversion.

Sporadic cases of cell-mediated immunity (CMI) in persons exposed to hepatitis C (HCV) but evidently uninfected have been reported. To further define this, we measured CMI in individuals without evidence of HCV infection, that is, negative for HCV-antibodies (anti-HCV) and RNA, residing in a rural Egyptian community where prevalence of anti-HCV was 24%. Cell-mediated immunity (CMI) measured by interferon-gamma (IFN-gamma) enzyme-linked immunospot (ELISPOT) assay, confirmed by intracellular staining using flow cytometry, against HCV peptides was measured in seronegative individuals with high-risk (HR) and low-risk (LR) exposures to HCV. Thirteen of 71 (18.3%) HR subjects but only 1 of 35 (2.9%) LR subjects had detectable CMI (P = 0.032). These data are compatible with the hypothesis that exposures to HCV may lead to development of HCV-specific CMI without anti-HCV and ongoing viral replication. We speculate induced CMI clears HCV sometimes when anti-HCV is not detectable, and HCV-specific CMI is a useful surrogate marker for exposure to HCV.

Associations of pesticides, HCV, HBV, and hepatocellular carcinoma in Egypt.

The rate of hepatocellular carcinoma (HCC) is increasing in Egypt where the major risk factors are chronic infections with hepatitis B and C viruses (HBV and HCV). A major segment of the population is employed in agriculture, raising the possibility that exposure to pesticides is an additional risk factor for HCC. The objective of this study is to investigate pesticides as environmental risk factors for HCC while taking into account viral risk factors. We conducted a case-control study of 236 subjects with confirmed HCC recruited from the National Cancer Institute, Cairo University, Egypt, and 236 controls matched on sex, age group and urban-rural status recruited from orthopedic department, Cairo University Hospital, Egypt. Patients who agreed to participate signed a consent form, answered a questionnaire and gave a blood sample for hepatitis virus testing. The manuals of the Ministry of Agriculture for approved use and type of pesticides since 1965 were linked to the questionnaire data for types of crops and pests that the subject had to combat, to attribute specific pesticides that were used by each subject. Subjects also reported duration of the exposure (years). Case-control comparisons in these data were stratified by sex, age group, and urban vs. rural residence. Data were analyzed using unconditional logistic regression models adjusting for age, HCV RNA, and current hepatitis B infection. Among rural males, the adjusted odds ratio (OR) for organophosphorus compounds was 2.7 (95% CI = 1.3-5.3) and for carbamates it was 2.9 (95% CI = 1.4-5.8). No statistically significant associations between HCC and pesticides were observed for urban males or for females. As expected, the strongest risk factors for HCC in this study were HCV RNA (OR = 16-17) and current HBV infection (OR = 27-28). This study therefore suggests that exposures to organophophorus and carbamate pesticides are additive risk factors to current HCV and HBV infection among rural males. Future investigation should address the possible hepatocarcinogenicity of pesticides using biomarkers of exposure and other techniques to better estimate dose-response relationships.

Case-control study of non-Hodgkin's lymphoma and hepatitis C virus infection in Egypt.

BACKGROUND: Chronic infection with hepatitis C virus (HCV) has been associated in some studies with increased risk for B-cell non-Hodgkin's lymphoma (NHL). To assess this further, we conducted a case-control study in Egypt, where HCV prevalence is extremely high. METHODS: Cases with B-cell NHL (N = 227) were recruited from the National Cancer Institute of Cairo University, a major referral centre. Controls (N = 227) were patients with fractures being treated at the Kasr El-Aini Orthopaedic Hospital, from the same referral base as the cases, and were frequency-matched by gender, rural versus urban birthplace, and age. Subjects were interviewed about their medical history and possible risk factors, and blood samples were collected for HCV diagnostic tests. Anti-HCV and HCV RNA were determined by enzyme-linked immunoassay and reverse transcription-polymerase chain reaction, respectively. Odds ratios (OR) and 95% CI were calculated from logistic regression models. RESULTS: Overall, 42% of subjects were anti-HCV positive and 33% had HCV RNA. There was a statistically significant unadjusted association of HCV RNA with NHL (OR = 2.3, 95% CI: 1.5, 3.5), which differed slightly by gender (males: OR = 2.1, 95% CI: 1.2, 3.7 versus females: OR = 2.5, 95% CI: 1.3, 4.8). Anti-HCV without HCV RNA was not associated with case status (OR = 0.9, 95% CI: 0.5, 1.6). After adjustment for age, gender, rural versus urban birthplace, and rural versus urban current residence, the association of HCV RNA with the risk of NHL remained statistically significant (OR = 2.9, 95% CI: 1.9, 4.5). CONCLUSIONS: These data support the hypothesis that NHL is a malignant outcome of chronic HCV infection.

Hepatitis c in a community in Upper Egypt: risk factors for infection.

This investigation's objective was to identify risk factors for hepatitis C virus (HCV) in a village in Upper Egypt with a moderately high prevalence (8.7%) of antibodies to HCV (anti-HCV). A representative sample of 6,012 (63%) of the 9,581 village inhabitants was included in the study. A questionnaire solicited information regarding risk factors for infection, and blood samples were tested for anti-HCV. Parenteral risks identified in age-adjusted analysis included blood transfusions, dental procedures, hospital admission, surgery, complicated deliveries, history of injection therapy for schistosomiasis, and history of frequent injections. Circumcision was pervasive and was not associated per se with ant-HCV; however, circumcision by an informal, rather than formal, health care provider was associated with anti-HCV among young men and boys. The results did not reveal any unique community-acquired exposures that caused HCV infections: inhabitants who had tattoos, who smoked goza, who were shaved by a community barber, or who had their ears pierced were not at greater risk for anti-HCV than those who did not. Risks identified in multivariate analysis for both those older and younger than 30 years included prior parenteral therapy for schistosomiasis and blood transfusion; for those 30 or younger, circumcision by an informal rather than formal health care provider, and frequent injections; and for those older than 30, never attending college, invasive medical procedures, and complicated deliveries. Selecting for those with blood transfusion, prior parenteral therapy for schistosomiasis, and invasive medical procedures would identify less than half of those infected. Inclusion of frequent injections would identify 80% of those infected with HCV, but as a result of the pervasive use of injections, it would not discriminate from those uninfected. Nonetheless, general reduction of these exposures and assuring sterile practices are logical goals for intervention.

Role of hepatitis C infection in chronic liver disease in Egypt.

Hepatitis C virus (HCV) is considered the most common etiology of chronic liver disease (CLD) in Egypt, where prevalence of antibodies to HCV (anti-HCV) is approximately 10-fold greater than in the United States and Europe. Reported are results that show the role of HCV in both overt and occult CLD, the risk factors for CLD and for HCV infection, and the relative importance of chronic HCV, hepatitis B, or both in causing hepatic morbidity. Case patients included 237 new outpatients at the National Liver Institute. Controls comprised 212 sex- and age-matched neighbors without liver disease. Case patients were more likely than controls to report a history of blood transfusions, schistosomiasis, or parenteral therapy for schistosomiasis; to have anti-HCV, HCV RNA, hepatitis B surface antigen, and serum alanine aminotransferase (ALT) elevations; and to have abdominal ultrasound findings of cirrhosis, portal hypertension, and splenomegaly. Anti-HCV-positive case patients were more likely than anti-HCV-negative patients to be male, older, and farmers: to have received a blood transfusion or parenteral therapy for schistosomiasis; to have ALT elevations; and to have ultrasound findings of cirrhosis, portal hypertension, and spleen enlargement. Anti-HCV-positive controls were more likely than anti-HCV-negative controls to have received parenteral therapy for schistosomiasis. These data support the belief that HCV is the predominant cause of CLD in Egypt and suggest there is a large underlying reservoir of HCV-caused liver disease.

Mercury exposure and malaria prevalence among gold miners in Pará, Brazil.

Economic development, including resource extraction, can cause toxic exposures that interact with endemic infectious diseases. Mercury is an immunotoxic metal used in the amalgamation of gold, resulting in both occupational exposures and environmental pollution. A cross-sectional medical survey was conducted in 1997 on 135 garimpeiros in Para, Brazil, because of their risks of both mercury exposure and malaria transmission. Mean levels of blood and urine mercury were well above non-exposed background levels. Twenty-six subjects had malaria parasitemia: Health symptoms consistent with mercury exposure were reported, but neither symptoms nor signs correlated with mercury levels in blood or urine. We did not find a dose response relationship between mercury exposure and likelihood of prevalent malaria infection, but there was a possible reduction in acquisition of immunity that may be associated with conditions in gold mining, including mercury exposure.

Cross reactive cellular immune response to HCV genotype 1 and 4 antigens among genotype 4 exposed subjects.

BACKGROUND: Hepatitis C Virus (HCV) infection is a global health burden particularly in Egypt, where HCV genotype 4a (GT-4a) predominates. The prevention and control of HCV infection will remain a challenge until the development of an effective vaccine that protects against different genotypes. Several HCV GT-1-based vaccines are in different stages of clinical trials, but antigenic differences could make protection against other genotypes problematic. In this regard, data comparing the cell-mediated immune (CMI) response to different HCV genotypes are limited. We aimed to ex vivo investigate whether GT-1-based vaccine may protect against HCV GT-4 infections. This was carried out on samples collected from genotype 4 infected/exposed subjects. METHODS/PRINCIPAL FINDINGS: The CMI responses of 35 subjects; infected with HCV GT-4/or who had spontaneously-resolved the infection and 10 healthy control subjects; to two sets of seven HCV overlapping 15-mer peptide pools derived from both genotypes; and covering most of the viral proteins; were evaluated. This was carried out using an interferon gamma (IFNγ) enzyme-linked immunospot (ELISpot) assay. Peripheral blood mononuclear cells (PBMC) from 17 subjects (48%) responded to at least one peptide pool derived from GT-1b/GT-4a with 13 subjects responding to peptide pools from both genotypes. A strong correlation was found in the responses to both genotypes (r = 0.82, p<0.001; 95% confidence interval = 0.562-0.933). The average IFNγ total spot forming cells (SFC)/10(6) PBMC (±SE) from the responding subjects for GT-1b and GT-4a was 216±56 and 199±55, respectively (p = 0.833). Also, there were no significant differences between those who cleared their HCV infection or who remained HCV-RNA positive (p = 0.8). CONCLUSION/SIGNIFICANCE: Our data suggest that an effective GT-1b vaccine could protect from GT-4a infection. These data could help in HCV rationale vaccine design and efficacy studies and further our understanding of HCV cross protection against different genotypes.