Prevalence of GBV-C/hepatitis G virus viremia among chronic hepatitis B, chronic hepatitis C and hemodialysis patients in Turkey.

To the Editor: The newly discovered hepatitis G virus (HGV) or GBV-C are isolates of the same virus, which is a single-stranded RNA virus of positive polarity with 9362 nucleotides.1 It can be transmitted via blood transfusion and intravenous drug use, sexually, and from an infected mother to her child.2 High prevalences of GBV-C/HGV have been found in subjects with frequent parenteral exposure and in groups at high risk of exposure to blood and blood products, including drug abusers, hemodialysis patients, multitransfused individuals and haemophiliacs.3 Due to shared risk factors, coinfection of GBV-C/HGV with hepatitis B (HBV) or hepatitis C (HCV) viruses in chronically infected patients has been reported at frequencies ranging from 10 to 25%.4

Because the prevalence of GBV-C/HGV is unclear in Turkish population, we sought analyze the prevalence of GBV-C/HGV-RNA in the sera of different groups in the Turkish population. Three hundred and ten Turkish serum samples classified into four groups were studied. Sera of 85 hemodialysis patients, 80 chronic hepatitis B patients, 75 chronic hepatitis C patients, and 70 healthy persons (control group) were tested for the presence of GBV-C/HGV-RNA. The control group included apparently healthy individuals who had participated in occupational screening for a randomly selected viral hepatitis marker. Thirty-seven were male and 33 female with a mean age of 42.5±11.8 years (range, 20–65 years). None were positive for anti-HCV or for HBsAg.

RNA was extracted from 150 μl of serum using the Nucleospin Virus Kit (Biogene, Kimbolton, UK). Real-time PCR was performed using primer pairs and a probe located in the 5′ untranslated region (5′UTR) of GBV-C/HGV-RNA using the ABI Prism 7700 Sequence Detector System (Perkin Elmer, Foster City, Calif.). Data were analysed by Fisher’ s exact test. A P value less than 0.05 was considered significant.

GBV-C/HGV-RNA was detected in 52 of the 310 sera tested with an overall prevalence of 17%. The highest prevalence was encountered among chronic hepatitis B patients (28%) followed by hemodialysis patients (24%), chronic hepatitis C patients (6%), whereas the lowest prevalence rate of 4% was detected among healthy persons (Table 1). HGV was significantly more frequent in chronic hepatitis B patients, hemodialysis patients, and chronic hepatitis C patients than in healthy persons (P<0.05).

Table 1

GBV-C/HGV RNA positivity among the four groups.

Group	No. tested	HGV RNA
		No. positive	%
Chronic hepatitis B patients	80	23	29
Chronic hepatitis C patients	75	5	7
Hemodialysis patients	85	21	25
Healthy controls*	70	3	4
Total	310	52	17

P<0.05 versus other groups.

It has been documented that patients with chronic hepatitis often harbor more than one hepatitis agent.5 The apparent link between hepatotropic viral infections probably reflects common exposure and transmission patterns rather than a specific interdependence relation. Heringlake et al.6 reported a striking high prevalence of HGV-RNA among patients with viral hepatitis B, C and D reaching 16%, 20% and 36%, respectively. In our study, the prevalence rate of GBV-C/HGV was 7% in the chronic hepatitis C group. The relative low prevalence of GBV-C/HGV-RNA in this group may be explained by a similar reciprocal replication pattern among patients coinfected with HBV and HCV.7 This had been proposed by Raimondo et al.,8 who suggested that while long-lasting persistance of HCV is the rule in chronically infected individuals, clearence of GBV-C/HGV after years of chronic infection is a frequent event.

Several authors demonstrated a high prevalence of HGV in hemodialysis patients with a wide range between different countries.9 Our figure of 25% is similar to that observed in most countries, including Italy10 and Spain.11 However, lower and higher prevalences have been reported in other countries: 3% to 8% in Japan and Germany12,13 and 55% to 57% in Indonesia and France.14,15 These differences in the prevalence of GBV-C/HGV may be explained by epidemiological variations, including a variable rate of blood transfusions and a variable adherence to universal precautions. However, a methodological reason may also contribute to this variability. In the reported studies, most determinations are performed using noncommercial tests and different primers were amplified. An available commercial kit or at least unified criterion for the detection should be necessary to obtain useful data to compare the prevalence of GBV-C/HGV.

In conclusion, GBV-C/HGV-RNA is highly prevalent among the different Turkish patient populations, being highest in chronic hepatitis B patients. Although much information has been learned about GBV-C/HGV infection in the short time since the discovery of the virus, the clinical and pathological significance of this infection needs better evaluation, particularly in patients infected with other hepatitis viruses, and in hemodialysis patients.