May 2002, Volume 52, Issue 5

Editorial

HCV 3 in Pakistan: Does it offer More Hope for Cure and Control

S. A. Mujeeb  ( Blood Transfusion Services, Jinnah Postgraduate Medical Centre, Karachi. )

In 1989, a nucleic acid clone responsible for major cases of non A non B hepatitis was successfully isolated and named hepatitis C virus (HCV)1. It comprises a heterogenous of RNA viruses, showing approximately 70% homology overall. The classification of HCV genotypes is based on nucleotide sequence similarity, with the major groupings of sequence variants designated as HCV types and the more closely related groups within each type termed subtypes. The types are numbered and subtypes are identified by lower case letters assigned in order of discovery2. Uptil now 6 major types and 80 subtypes of HCV have been identified3. The genotype of an isolate can be determined by analysis of the genomic sequences (genotype) or by detection of genotype specific antibodies (serotyping). HCV genotypes reflect current infection, while serotypes may demonstrate exposure of the disease, current as well as past infections. HCV genotyping, serotyping may have different clinical applications. It can help in determining the efficacy of screening assays, epidemiology of HCV infection like type 3 appears to be detected more often in relation to intravenous drug users, development of vaccine, severity as well as the progression rate of the liver disease and efficacy of interferon or other antiviral treatment4. Pakistan seems to have high prevalence of hepatitis C virus type 3. Earlier Shat et al conducted a study at Aga Khan University Hospital, using genotyping methods, reported HCV type 3 strains among 87% (39/45) HCV reactive patients5. Later Zuberi and Arif, at Pakistan Medical Research Council, using serotyping methods, reported 79.5% (17l/275) prevalence of HCV type 3 strains among HCV related chronic hepatitis patients6. Nuzhat et al, at Liaquat National Hospital, Karachi, using serotyping methods also reported 64% (198/255) prevalence of HCV type 3 strain among HCV positive patients7.
Evidence has now accumulated that from a large number of studies demonstrating that HCV genotype is correlated with response to IFN- alpha therapy. HCV type 3 seems to respond more favourably to antiviral therapy8. HCV type 3 seems to be high in South East Asia like India, Bangladesh, Thailand and Singapore3. In Western Europe and USA, HCV type 1,2 and 3 are more prevalent, but HCV type 3 have been found more frequent among drug users9. In Pakistan unsafe injection practices have been attributed as a major cause of spread of HCV infection in the country10. It seems there can be a linkage between unsafe injection practices and HCV type 3 strain. Having high prevalence of HCV type 3 strain, Pakistan has a good hope for cure and control of the disease. Promotion of safe injections practices, early diagnosis and clinical management of HCV positive patients can bear more fruit in Pakistan.

References

1.Choo QU, Kuo G, Weiner AJ, et al. Isolation of a cDNA derived from a blood borne non A non B hepatitis genome. Science, 1989;244:359-62.
2.Enomoto N, Takada A, Nakao T, et at. There are two major types of hepatitis C virus in Japan. Biochem biopsys Res. commun., 1990;170:1021-5.
3.Dusheiko GM. Hepatitis C infection: from virology to management. In: Deeker R, Taroonon H, Hepatitis C 1997: essays and expert opinions on its natural history, epidemiology, diagnosis and therapy. Abbott Diagnostic Division. pp. 5-25.
4.Doom LJV, Kleter B, Pike I. et al. Analysis of hepatitic C virus isolates by serotyping and genotyping. J. Clin. Microhiol., 1996;34:1784-7.
5.Shah HA, Jafri W, Matik 1, et al. Hepatitis C virus (HCV) genotypes and chronic liver disease in Pakistan. J. Gastroenterol Hepatol., 1997;11:758-61.
6.Zuberi SJ, Arif A. Serotyping of Hepatitis C in Pakistan. J. Pak. Med. Assoc., 2002;52:218-19.
7.Ansari N, Ahmed A, Esmail J, et at. HCV Serotypes in Karachi, J. Pak. Med. Assoc., 2002;52:219-20.
8.Maertens G, Stuyer L. Hepatitis C virus geno-and serotypes: typing methods and clinical applications. In: Decker R, Troonen H, (eds.). Hepatitis C 1997: essays and expert opinions on its natural history, epidemiology, diagnosis, and therapy. Abbott Diagnostic Division. pp. 107-15.
9.Pawlotsky JM, Tsakiris F, Roudot-Thoraval C, et al. Relationship between hepatitis C virus genotype and source of infection in patients with chronic hepatitis C. J. Infect. Dis., 1995;171:1607-10.
10.Mujeeb SA. Unsafe injections: a potential source of HCV spread in Pakistan. 200 1;5 1-1-3.

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