TITLE: Prevalence of mixed infection by different hepatitis C
virus genotypes in patients with hepatitis C virus-related chronic
liver disease.
Multiple infection by different hepatitis C virus (HCV)
genotypes may be of great clinico-pathologic interest. In this
study we determined the effective prevalence of coinfections by two
or more HCV genotypes in 213 subjects with HCV-positive chronic
hepatitis by using genotype-specific polymerase chain reaction
(PCR), genotype-specific probe hybridization, and direct
sequencing.
The most prevalent genotype was HCV-1b (54%). HCV-2 (a/c) was
also prevalent (27%), and types 1a and 3a were found in 5% and 3%
of patients, respectively. A mixed infection was detected in 23
patients (10.8%): 4 out of 23 were coinfected by types 1a + 1b,
while the remaining 19 patients had a b + 2 (a/c) mixed infection.
Further analysis based on restriction fragment length polymorphism
(RFLP) on type-specific PCR products was used to verify genotyping
results. Only four coinfections (1a + 1b in 2 patients and 1b + 2
(a/c) in the remaining 2 patients, respectively) were confirmed by
enzyme cleavage.
All patients with true coinfection had long-lasting infection
and liver cirrhosis. Both true and false mixed infections resulting
from RFLP analysis were confirmed by direct sequencing of
type-specific amplification products. We also determined a
recurrent C/T transversion at position 618 in all sequenced
samples. In 4 cases another point mutation (G/A at position 626)
was found, reducing the number of mismatches between HCV-2 and
HCV-1b from 4 to 3 (or 2). Interestingly, all HCV-2 isolates
sequenced showed the highest degree of nucleotide homology with
HCV-2 subtype c, confirming the relatively high prevalence of this
subtype in Italy.
In conclusion, we showed the possibility of multiple infection
by different HCV types in the general population of chronically
infected patients without particular risk factors, even if in a low
percentage of cases. Further studies are needed to assess the
clinical relevance of chronic HCV infection with multiple
genotypes.
AUTHOR: Giannini C, Giannelli F, Monti M, Careccia G,
Marrocchi ME, Laffi G, Gentilini P, Zignego AL, Institute of
Internal Medicine, University of Florence School of Medicine,
Italy.
SOURCE: J Lab Clin Med 1999 Jul;134(1):68-73
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