HCV Treatment and Monitoring the Role of the BloodBorne Virus Specialist Testing Service

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HCV Treatment and Monitoring the Role of the
Blood-Borne Virus Specialist Testing
Service Specialist Virology Centres, Edinburgh
and Glasgow
Infection with Hepatitis C virus (HCV)
frequently results in long-term carriage of the
virus in 85 of cases and can lead to significant
disease. Cirrhosis will develop in 80 of
patients 20-30 years post-infection and a small
population of patients will progress to
hepatocellular carcinoma. Treatment with
ribavirin and interferon a is now available for
suitable patients in Scotland. The Blood Borne
Virus Specialist Testing Service (BBV STS) has an
important role in the assessment for treatment
and monitoring of patients. Treatment length and
outcome is influenced by the HCV genotype with
which the patient is infected. Treatment success
can be assessed by monitoring HCV in the blood by
PCR. Clinical Guidelines for Treatment The
National Institute of Clinical Excellence (NICE)
has developed guidelines for the treatment of
moderate to severe chronic HCV infection. In
patients infected with genotypes 2 or 3,
combination treatment with pegylated interferon-a
and ribavirin for 24 weeks is recommended.
Patients with genotypes 1, 4, 5 or 6 undergo a
pre-treatment quantitative PCR. After 12 weeks of
combination therapy, a second quantitative PCR is
carried out. Only if there has been a ? 2 log10
drop in viral load will treatment continue for a
further 36 weeks. Longer treatment is necessary
with these genotypes due to poorer response.
Genotyping There are 6 major genotypes of HCV.
Samples are genotyped by sequencing the 5'
non-coding region using the Bayer HCV 5'NC
Genotyping kit (Edinburgh) or by an in-house
method targeting the core region (Glasgow). Both
methods give comparable results as assessed by
external quality assurance schemes. Figure 1. HCV
genotypes in Scottish patients In the
year 2005-06, 1228 specimens were genotyped. More
than 90 of patients were found to be infected
with either genotypes 1 or 3, with roughly equal
numbers of each genotype (Figure 2). There are
smaller numbers of other genotypes e.g. lt5 were
genotype 2 and lt1 were genotype 4, which is
mostly commonly associated with the Middle East
and Mediterranean area. No samples were found to
contain genotypes 5 or 6.
Quantitative PCR HCV viral load in the blood is
measured using the Roche Cobas Amplicor assay,
which has a range of 600 to 500,000 IU/ml.As
discussed above, this test is performed prior to
treatment and, if the patient carries genotypes
1, 4, 5 or 6, after 12 weeks of treatment There
were 812 HCV quantitative PCR tests carried out
last year, with requests arising mainly from
Lothian, Greater Glasgow and Grampian health
boards. Summary It is estimated that around
50,000 people in Scotland have been infected with
HCV but that two thirds remain undiagnosed.
Therefore the BBV STS will continue to play an
important role in the assessment and monitoring
of HCV-infected individuals for a number of
years. The technology involved in genotyping and
quantitative PCR continues to evolve and the
laboratories will continue to adapt the service
to cope with this change, and also to remain at
the forefront of diagnosis. Service
developments SVC Glasgow have developed a more
rapid and less expensive method for genotyping
HCV using real-time PCR. This uses three
type-specific probes for genotypes 1, 2 and 3.
Other genotypes can still be identified using
sequencing. SVC Edinburgh have improved their
genotyping method to improve sensitivity and
decrease the turn-around-time.