ABSTRACT
Molecular epidemiological studies of hepatitis C virus (HCV) in the Caribbean may help to specify the origin and spread of HCV infection. Indeed, the Caribbean population is intermixed from European and African origins and geographically close to the American continent. We characterized HCV genotypes in the Caribbean island of Martinique. HCV genotypes were analyzed by sequencing or reverse hybridization in the 5′ noncoding region (5′NC) in 250 HCV-monoinfected and 85 HCV-human immunodeficiency virus (HIV)-coinfected patients. In addition, sequencing in the nonstructural 5B (NS5B) gene was required to determine the subtype or to perform phylogenetic analysis in selected samples. Genotypes 1 to 6 were found, respectively, in 84.4, 6.8, 5.2, 2.8, 0.4, and 0.4% of 250 HCV-monoinfected patients and in 71.7, 7.1, 15.3, 5.9, 0, and 0% of 85 HCV-HIV-coinfected patients. HCV-1b was found in 66.4% of the HCV-monoinfected patients and was associated with blood transfusion, whereas HCV-1a was detected in 41.2% of the HCV-HIV-coinfected patients and was associated with intravenous drug use (IVDU). The HCV-3 strains belonged to subtype 3a and were linked to IVDU. Phylogenetic analyses were focused on HCV-2 and HCV-4, which are common in Africa. Two opposite patterns were evidenced. NS5B sequences from 19 HCV-2 isolates were affiliated with many different subtypes described either in Europe or in West Africa, suggesting an ancient radiation. In contrast, seven of the nine HCV-4 NS5B sequences ranged within HCV-4a and HCV-4d clusters spreading in continental France by the IVDU route. Epidemiological data demonstrate the recent introduction of HCV-4a and -4d subtypes into the Caribbean.
Hepatitis C virus (HCV), which is endemic in most parts of the world, is a major cause of parenterally transmitted hepatitis. However, its prevalence and incidence appear to be variable both geographically and temporally due to the distribution and evolution of risk factors (45). The genus hepacivirus consists of 6 major clades (genotypes) further divided into subtypes (31, 34). HCV genotypes 1, 2, and 3 are distributed worldwide, whereas genotypes 4, 5, and 6 are found mainly in specific areas (48). For example, genotype 4 is relatively frequent in many Central African countries and highly prevalent in Egypt (12, 22, 24, 28, 38, 47), whereas genotype 2 is more frequent in neighboring countries in West Africa (15, 32). Data on HCV infection in the Caribbean region are scarce. A few studies have reported a similar HCV infection prevalence to that in the United States and Europe (2, 6, 11, 16, 35), but the HCV genotype distribution remains to be determined. A predominance of HCV subtype 1a has been described in the Dominican Republic (23) and in Puerto-Rico (30), but no information is available on HCV genotype distribution in the Lesser Antilles archipelago.
Molecular epidemiological studies of HCV in the Caribbean may provide important clues for understanding the origin and spread of HCV infection. The Caribbean population is of mixed European and African origin but is also geographically close to the American continent. In addition, because slaves were imported from Africa between the 17th and mid-19th century, such a study might contribute to estimations of the HCV-type radiation time. The great diversity of HCV subtypes in Africa has been proposed to reflect ancient HCV spreading dating back several centuries (36). However, by analysis of the branching pattern of phylogenetic trees (14) and by using back-calculation approach (9), it has been suggested that HCV transmission increased exponentially in the second part of the 20th century. Furthermore, the epidemic behavior of the hepatitis C virus was recently reevaluated and is now considered to be mainly the result of subtype-specific transmission patterns (21, 27).
HCV genotyping is important in the clinical setting, since genotype 1 and 4 isolates are less likely to respond to interferon (IFN) therapy than genotypes 2 and 3 (10, 18, 48). Increased knowledge of the distribution of HCV genotypes in the African-Caribbean population might also be useful for studies on response to IFN treatment in African-Americans. Recent studies in the United States have suggested that black patients show impaired responsiveness to IFN treatment (8, 17, 29), which might be partially overcome by alpha IFN (IFN-α)-ribavirin combination therapy (20). Moreover, studies in the United States suggest a lower frequency of HCV infection clearance (41) and a slower progression of fibrosis (46) in African-Americans than in Caucasians. Association of particular HCV genotypes and genetic background (40) could influence the clinical outcome of infection in Caribbean patients. In addition, HIV prevalence is high in the region (44), and HIV coinfection is known to accelerate HCV-related liver disease (37, 49).
To determine the pattern of HCV infection in the Lesser Antilles, we analyzed HCV genotype distribution in a wide population followed in the hepatology, hemodialysis, and human immunodeficiency virus (HIV) outpatient units on the island of Martinique. We found that the distribution of HCV genotypes in this French Caribbean island was similar to that seen in continental France. A predominance of blood transfusion-associated HCV-1b and intravenous drug use (IDVU)-associated HCV-1a was found. Furthermore, phylogenetic analyses demonstrated (i) a high diversity of HCV-2 in Martinique, suggesting an ancient evolution and/or reiterative introductions of this type, and (ii) a recent spread of HCV-4a and -4d subtypes from Europe to the Caribbean via the IDVU route.
MATERIALS AND METHODS
Study populations.The present study was carried out in Martinique, a French West Indies island with 390,000 inhabitants. A total of 335 samples (Table 1), 250 from HCV-monoinfected patients (groups I and II) and 85 from HCV-HIV-coinfected patients (group III), were obtained as follows. Group I (Hepatology unit) consisted of 187 consecutive samples referred to the laboratory for HCV genotyping between 1999 and 2001. During the same period, a total of 289 patients had been admitted to the hepatology unit for HCV chronic infection. Liver disease severity in patients who had undergone a liver biopsy was scored by using the Metavir classification. Group II (hemodialysis unit) consisted of 63 consecutive HCV-RNA positive samples from a cohort of 370 hemodialysis patients and 94 patients with prior renal transplantation. Group III (HIV outpatient unit) consisted of all 85 samples with detectable HCV viremia from the 112 HCV serology-defined coinfected patients in 1341 HIV-infected patients who attended the outpatient clinic between 1988 and 2001. Centers for Disease Control AIDS classification data were available for 82 of these 85 patients at the date of sampling and showed that 35, 26, and 21 were stage A, B, and C, respectively. The epidemiological data for the 3 groups are summarized in Table 1.
Epidemiological features of patients included in the study
Specimen.Sera were separated from whole blood within 6 h after collection, and stored at −80°C until RNA extraction.
Trugene HCV noncoding region sequencing.All samples except those from the hemodialysis patients were sequenced in the 5′ noncoding region (5′NC). RNA was extracted from 100 μl of serum and reverse transcription-PCR (RT-PCR) performed by using the Amplicor HCV assay (Roche Diagnostics, Meylan, France). After purification with a High-Pure PCR extraction kit (Boehringer Mannheim, Penzberg, Germany), the amplicons (244 bp) were subjected to the CLIP reaction (Visible Genetics, Toronto, Ontario, Canada) according to the manufacturer's instructions. Bidirectional sequencing of the 183-bp template resulting from the CLIP reaction was performed on a Long-Read tower, an automated DNA sequencer that uses ultrathin disposable gels. Each sequence was aligned with reference sequences from the GeneLibrarian database, which contains ca. 200 HCV sequences from the six major genotypes, including 24 subtypes.
LiPA genotyping.Hemodialysis samples were analyzed by using a line probe assay (LiPA [INNO-LiPA II; Innogenetics, Zwijnaarde, Belgium]). After extraction and RT-PCR as described above, the biotin-labeled amplified products generated with Amplicor were hybridized to type-specific nucleic acid probes on membrane strips under high-stringency conditions. After hybridization, alkaline phosphatase-labeled streptavidin was added. The hybridization pattern discriminates among HCV types 1a, 1b, 2a/c, 2b, 3a, 3b, 3c, 4a to h, 5a, and 6a.
Sequencing and phylogenetic analyses of HCV NS5B.RNA was extracted from 250 μl of serum by using TRIzol (Life Technologies, Cergy-Pontoise, France). RT and “touchdown” PCR with degenerate primers (Sn755 and Asn1121) were performed as described previously (13, 21). The PCR products were purified by using Microcon-50 microcontractors (Amicon), and both strands were sequenced by using an ABI Prism 377 automated sequencer with the ABI Prism BigDye terminator cycle sequencing ready reaction kit (Perkin-Elmer, Roissy, France). NS5B 329-bp sequences were aligned by using CLUSTAL W, v1.8 (42). Phylogenetic analyses were carried out by using PAUP*4.0b10 (39). Distance analyses were performed by using the Kimura two-parameter and maximum- likelihood (ML) models of character substitution. The substitution rate-matrix parameters and the nucleotide frequencies were estimated in heuristic ML searches (simple addition sequence). Maximum-parsimony (MP) analyses were conducted with the heuristic search option (10 random addition replicates). Bootstrapping (1,000 replicates) was used to evaluate the robustness of the various inferred clades.
The following sequences were included in the analyses: HCV-1a (D10749, M62321, and M67463), HCV-1b (AF054250 and M58335), HCV-1c (D14183 and D14853), HCV-1d (L38378 and L48496), HCV-1e (AY265450 and L38361), HCV-1f (L38371), HCV-1g (AF271797 and AF271798), unspecified HCV subtype 1 (AF037230 to AF037235, AF037237, AF037238, AY257069, AY257086, AY257087, AY265431, and AY265439), HCV-2a (AB047639, AB047640, AF238486, and D00944), HCV-2b (AB030907 and D10988), HCV-2c (AJ291280, D50409, and L38364), HCV-2d (AF037243, AF037244, and L29634), HCV-2e (D49760 and D49780), HCV-2f (D49769 and D49777), HCV-2i (L48492 and L48499), HCV-2j (D86532), HCV-2k (AB031663 and D86529), HCV-2l (L48493 and L48494), unspecified HCV subtype 2 (AF037239, AF037240, and AF037245 to AF037254), HCV-3a (AJ251246, D17763, and X76918), HCV-3b (AF279121, D37853, and D49374), HCV-3c (D16613), HCV-3d (D16621), HCV-3e (D16619), HCV-3f (D16615 and L78842), HCV-3g (X91303 and X91418), HCV-3 h (AF279120), HCV-10a (D49762, D49779, and D63821), HCV-4a (AF271800, AF271801, AJ291245, AJ291252, AJ291253, AJ291255, AJ291259, AJ291261, AJ291268, D86533, D86535, and Y11604), HCV-4c (L29602 and L29605), HCV-4d (AJ291263, AJ291292, D86537, and D86538), HCV-4e (L29590 and L29626), HCV-4f (AJ291250, AJ291283, and L38370), HCV-4g (L29618), HCV-4 h (AJ291249 and L29611), HCV-4i (L36437), HCV-4j (L36438), HCV-4k (AJ291294 and L44597), HCV-4aB (AJ291282 and AJ291284), HCV-5a (AF064490), and HCV-6a (Y12083).
All of the new NS5B sequences characterized in the present study have been submitted to GenBank under the indicated accession numbers: Mart01 (AY257422), Mart02 (AY257423), Mart03 (AY257424), Mart10 (AY257430), Mart11 (AY257431), Mart17 (AY257437), Mart18 (AY257438), Mart19 (AY257439), Mart20 (AY257440), Mart21 (AY257441), Mart22 (AY257442), Mart23 (AY257443), Mart24 (AY257444), Mart25 (AY257445), Mart26 (AY257446), Mart27 (AY257447), Mart30 (AY257448), Mart38 (AY257456), Mart39 (AY257457), Mart40 (AY257458), Mart41 (AY257459), Mart42 (AY257460), Mart43 (AY257461), Mart44 (AY257462), Mart45 (AY257463), Mart46 (AY257464), Mart47 (AY257465), Mart48 (AY257466), and Mart50 (AY257467).
Statistical analysis.The distribution of HCV genotypes, age, and risk factors was compared by using the χ2 test, Fisher test, and analysis of variance (ANOVA).
RESULTS
Distribution of HCV genotypes.The overall distribution of HCV genotypes in the HCV-monoinfected patients from the hepatology and hemodialysis units (groups I and II) and in the HCV-HIV-coinfected cohort (group III) is summarized in Table 2. Genotype 1 was predominant in both HCV-monoinfected and HCV-HIV-coinfected patients, being found in 211 (84.4%) of 250 samples and 61 (71.7%) of 85 samples, respectively. HCV subtype 1b was predominant in the HCV-monoinfected patients (n = 166; 66.4% of genotype 1 samples), whereas subtype 1a was predominant in the HCV-HIV-coinfected patients (n = 35; 41.2% of genotype 1 samples). Genotype 1c was identified in one and two samples from HCV-monoinfected and HCV-HIV-coinfected patients, respectively. In the HCV-monoinfected and HCV-HIV-coinfected patients, 17 (6.8%) and 6 (7.1%) samples, respectively, were genotype 2. Genotype 3 was more frequent in the HCV-HIV-coinfected patients than in the HCV-monoinfected patients, corresponding to 15.3 and 5.2% of the samples, respectively (P = 0.003, χ2 test). Genotype 4 was detected in seven (2.8%) and five (5.9%) samples from HCV-monoinfected and HCV/HIV-coinfected patients, respectively. Genotypes 5 and 6 were each detected once in HCV-monoinfected patients.
Distribution of HCV genotypes in HCV-monoinfected and HCV-HIV-coinfected patients
HCV genotypes according to clinical data.Liver biopsy Metavir scores were available for 135 patients from the hepatology unit. Of these, 22 (19.5%) of 113 patients with genotype 1 showed cirrhosis compared to 2 (9.1%) of 22 patients with other genotypes, but the difference did not reach significance (P = 0.36, χ2 test). In the HCV-HIV-coinfected patients, Centers for Disease Control staging of HIV disease was not linked to HCV genotype. In the HCV-monoinfected group, patients with HCV subtype 1b or 2 were significantly older (means ± the standard deviations [SD], 59 ± 15 and 62 ± 15 years, respectively) than patients with genotype 1a or 3 (47 ± 15 and 39 ± 6 years, respectively) (P < 0.001, ANOVA) (Fig. 1). Similarly, in the HCV-HIV-coinfected group, patients with genotype 1b were significantly older (47 ± 17 years) than those with genotype 1a or 3 (38 ± 10 and 35 ± 5 years, respectively) (P < 0.005, ANOVA). In the HCV-monoinfected group, the male/female ratios were 1.75, 0.69, 0.54, 1.6, and 2.5 for HCV-1a, HCV-1b, HCV-2, HCV-3, and HCV-4, respectively. In the HCV-HIV-coinfected group, the male/female ratios were 3.37, 1.67, 2, and 2.25 for HCV-1a, HCV-1b, HCV-2, and HCV-3, respectively, while five women and no men were found to be infected with HCV-4 (Table 3).
Age distribution of HCV-monoinfected patients according to genotype. Percentiles (10th, 25th, 50th, 75th, and 90th) are represented by horizontal lines. HCV-monoinfected patients with HCV subtype 1b or 2 were significantly older than patients with genotype 1a or 3 (P < 0.001, ANOVA).
Epidemiological characteristics of patients with the HCV genotype 4
HCV genotypes according to risk factors.The HCV genotype distribution as a function of the source of HCV infection (IVDU, hemodialysis, blood transfusion, hemophilia, or other route of HCV transmission) is shown in Fig. 2. HCV subtype 1a was more frequent in the IVDU group (42% of samples) than in the hemodialysis (22%), blood transfusion (12%), or hemophilia (25%) groups (P < 0.05, χ2 test); in contrast, subtype 1b was less frequent in the IVDU group (21%) than in the other three groups (70, 75, and 69%, respectively) (P < 0.01, χ2 test). HCV genotype 2 was present in a small percentage of cases in most groups, i.e., IVDU (3%), hemodialysis (3%), blood transfusion (7%), and unknown risk factors (9%). One HCV-2 strain has been previously reported as transmitted accidentally by a blow in a fight (1). HCV genotype 3 was associated with IVDU (17%) rather than with blood transfusion (3%) or hemophilia (6%); no HCV-3 was detected in the hemodialysis group. HCV-4 was found mainly in IVD users (14%). Moreover, two of the three hemodialyzed patients infected with HCV genotype 4 also had a past history of IVDU prior to hemodialysis. In contrast, subtype 4f was detected in only two patients lacking the IVDU risk factor: one with a history of blood transfusion and one who had undergone renal transplantation (Table 3). In the HCV-monoinfected patients without known risk factors the pattern of HCV genotype distribution approached that observed in hemodialysis or blood transfusion groups, with a predominance of subtype 1b. Among the HCV-HIV-coinfected patients with a sexual risk factor for HIV acquisition (n = 28, Fig. 2), the subtype 1a/1b ratio and genotype 3 frequency appeared to be intermediate between the patterns observed in the hemodialysis-blood transfusion groups and the IDVU group. Four (15%) HCV-2 strains were found in the HCV-HIV-coinfected patients with a sexual risk factor.
Distribution of HCV genotypes according to HCV risk factor. Note that genotype 1c (two patients with IDVU and 1 HCV- monoinfected patient with unknown risk factor), genotype 5 (one HCV-monoinfected patient with unknown risk factor), and genotype 6 (one HCV-monoinfected patient with unknown risk factor) samples are not shown in the Figures. HCV subtype 1a was more frequent in the IVDU group than in the hemodialysis, blood transfusion, or hemophilia groups (P < 0.05, χ2 test), whereas subtype 1b was less frequent in the IVDU group than in the other three groups (P < 0.01, χ2 test).
Phylogenetic analysis.NS5B sequence analysis was required to determine the subtype for 16 samples that could not be specified by LiPA or CLIP sequencing. NS5B phylogenetic analysis confirmed that these patients were infected with HCV genotype 1 (4 with HCV-1a and 12 with HCV-1b) (Fig. 3a). The NS5B phylogenetic analysis of an a HCV-3a isolate is also shown (Fig. 3c). Twenty NS5B sequences were obtained from nineteen HCV genotype 2-infected patients and showed a broad diversity (Fig. 3b). Some strains were closely related to isolates reported ubiquitously (2a, 2b, and 2c), in Europe (2l), in Russia/Moldovia (2j), or in West Africa (Mart17/46 with BF70) or were not affiliated with any previously described subtype (e.g., Mart11, Mart44, and Mart45) (Fig. 3b). NS5B sequences were obtained from nine patients with HCV-4 infection. Only three HCV-4 subtypes were found, these being HCV-4a, HCV-4d, and HCV-4f, with five, two, and two isolates, respectively (Fig. 3d). The seven HCV-4a and HCV-4d isolates were closely related to HCV strains previously characterized in intravenous drug users in continental France (FrSSD isolates) (21) and were clearly distinct from isolates originating from Africa (see bootstrap values). Interestingly, all patients infected with HCV-4a or HCV-4d had an IVDU risk factor (Table 3). Five HCV-4-HIV-coinfected patients had been diagnosed as having an HIV infection in continental France before they came to Martinique. Similarly, two patients with IVDU prior to hemodialysis were infected with HCV before they came to Martinique (Table 3).
Phylogenetic analyses of the NS5B gene (positions 7938 to 8269) from HCV isolates characterized in Martinique Island (Mart). These trees are strict consensus cladograms of 6, 492, 17, and 255 trees obtained through MP heuristic analyses for HCV-1 (a), HCV-2 (b), HCV-3 (c), and HCV-4 (d) NS5B sequences characterized in Martinique and 27 HCV-1 (a), 35 HCV-2 (b), 17 HCV-3 (c), and 40 HCV-4 (d) reference sequences. The trees are artificially rooted by using five non-HCV-1 (a), -HCV-2 (b), -HCV-3 (c), or -HCV-4 (d) reference sequences as outgroup (isolates HCV-1, HC-J6, NLZ1, ED43, SA13, and EUHK2). The HCV subtypes are indicated above their respective branches. Bootstrap percent values are indicated above (ML) and below (MP) the branches for 1,000 replicates. The sampling location of reference isolates is shown in parentheses after the sequence name, when available. Isolates from Martinique are indicated in the figure, followed by the associated risk factors (blood transfusion, IVDU, sexual risk of HIV acquisition, hemophilia, and “other”). Note that HCV-1 isolates Mart13 and Mart32 and HCV-2 isolates Mart17 and Mart46 were characterized from the same patient, respectively. The HCV Mart39 isolate resulted from the transmission of HCV Mart38 in a fight (1).
DISCUSSION
In a previous study, we reported that the prevalence of HCV infection in Martinique blood donors (0.05%) was similar to that in continental France (6). The prevalence of HCV infection in HIV-infected patients from Martinique is ca. 9% (unpublished data), while in Europe and the United States it ranges between 8 and 30% as a function of the distribution of risk factors (49). The fact that the prevalence of HCV-HIV coinfection in Martinique is at the lower end of this range might be explained by the lower frequency of IVDU.
As in the United States and Europe (5, 19), genotypes 1, 2, and 3 were responsible for the majority of chronic HCV infections in Martinique. The predominance of HCV genotype 1 appeared to be more pronounced in Martinique (84% of HCV-monoinfected patients) than in continental France, where a frequency of 56.6 to 57% has been reported (19). In contrast, HCV genotypes 2 and 3 are more frequent in continental France (14 and 22%, respectively) than in Martinique. Interestingly, in the United States, African-American patients with HCV infection have a higher frequency of genotype 1 (88 to 96%) than Caucasian patients (65 to 76%) and very low rates of HCV genotypes 2 and 3 (3 and 1%, respectively) (5, 17, 20, 29, 46). However, at the subtype level, the distribution in Martinique, with a predominance of subtype 1b, as in continental France, differs from that seen in African-Americans in the United States, in whom subtype 1a predominates (29).
The association between HCV subtype 1b and old age suggests a change with time of HCV genotype transmission in Martinique, as in continental France (26). Due to the low number of liver biopsies from non-subtype 1-infected patients, we were unable to confirm the previously reported association between genotype 1b and old age and severity of HCV disease (3). HCV-1a (41.5%) and HCV-3 (15.3%) were more prevalent in HCV-HIV-coinfected patients than in the HCV-monoinfected group. These genotypes are associated with an history of IVDU (19, 26), which was the route of HCV infection in two-thirds of the HCV-HIV-coinfected population studied here. In contrast, HCV genotypes 1b and 2 were more frequent in patients with blood transfusion or unknown risk factors. The sex ratio also tended to be higher in the HCV-1a or HCV-3 groups than in the HCV-1b or HCV-2 groups. In the HCV-infected patients with hemophilia with past exposure to noninactivated blood factor concentrates prepared in continental France, HCV subtype 1b was the most frequent, as previously shown in Europe (43). A study carried out in another Caribbean island, the Dominican Republic (23), showed a marked predominance of subtype 1a (59%), which was suggested to result from frequent population movements between this island and the United States or from transfusion of blood products imported from the United States. In Martinique, the HCV genotype distribution might reflect relationships with continental France and the relatively low frequency of IDVU in the island.
HCV isolates that were uncharacterized by using LiPA or CLIP sequencing (16 samples) were sequenced in the NS5B region, such analysis providing a more accurate subtype assignment of genotype 1 isolates than 5′NC methods (7, 25). Interestingly, all of these HCV-1 isolates were shown by NS5B phylogenetic analysis to belong to the 1a or 1b subtypes without any affiliation to other genotype 1-African isolates. In addition to genotype 1, African HCV strains also include genotypes 2, 4, and 5. Because only one patient (with an unknown risk factor) was infected with HCV-5, which is geographically restricted to southern Africa, we focused our phylogenetic analyses on types 2 and 4 to determine whether specific Caribbean clades could be observed. Two opposite patterns were seen for types 2 and 4. Patients infected with type 2 had various risk factors, and the 19 strains characterized in the NS5B gene belonged to many different subtypes, suggesting an ancient radiation. This raises the question of whether HCV-2 introduction during slave importation could be sustained by the topology of such an HCV-2 phylogenetic tree. Whether these viruses reflect the ancient arrival of viruses during the 17th to the 19th centuries requires further study, but this wide HCV genotype 2 affiliation is similar to that observed in West Africa (15) and could reflect long-term endemicity of HCV-2 in Martinique. In contrast, the tree topology indicated that all type 4 sequences from the present study belonged to only three well-characterized clades. Subtypes 4a and 4d were associated with IDVU risk and closely related to isolates associated with the emergence of these clades in drug users in continental France (21). This was confirmed by the fact that all HCV-4a- or HCV-4d-infected patients had acquired HCV infection in continental France before they moved to Martinique. With the exception of two HCV-4f strains previously characterized in patients from Cameroon and Gabon (21, 24, 38) and acquired by blood transfusion and by renal transplantation in continental France, no Martinican strains clustered within sub-Saharan type 4 subclades.
These findings have potential implications for the debate on the time of HCV spread in Africa (14, 28, 36). The majority of the population of Martinique are descended from African people. An important contingent was brought from West Africa during the slave trade in the 17th to the mid-19th centuries, and a second wave came as free laborers from Central Africa during the mid-19th century (4). HCV genotypes 2 and 4 are, respectively, frequently observed in West and Central Africa (12, 22, 24, 28, 38, 47). Together with the quasiabsence of genotype 4 reported in Brazilians of African descent (33), our phylogenetic observations argue in favor of (i) a recent outbreak of HCV-4 in sub-Saharan Africa; (ii) a limited, or no, introduction of HCV from Central Africa to the Caribbean during slave importation; and/or (iii) a lower efficacy of HCV-4 transmission through secondary cases, as suggested by Pybus et al. (27). In contrast, HCV-2 radiation in West Africa may have occurred several centuries ago.
In conclusion, studies in the Caribbean islands may provide new knowledge on the epidemiology of HCV infection. The present study shows that the distribution of HCV genotype 4 in Martinique is similar to that in Europe and demonstrates the recent introduction of HCV subtypes 4a and 4d from continental France. Despite the fact that the low frequency of IDVU in Martinique has probably impaired the expansion of these HCV-4a and HCV-4d isolates, they may spread over the boundaries of the IVDU route. Recent reports suggest that HCV genotype 4 react poorly to IFN and ribavirin (10, 18). In addition, the impaired response to IFN in African-Americans and the differences in the natural history of HCV infection compared to Caucasians (8, 17, 20, 29, 41, 46) make further studies on African-Caribbean populations necessary. In this setting, the emergence of HCV genotype 4 in the Caribbean should be carefully monitored.
FOOTNOTES
- Received 14 April 2003.
- Returned for modification 17 July 2003.
- Accepted 25 September 2003.
- American Society for Microbiology
