HCV‐RNA In Sural Nerve From Hcv Infected Patients With Peripheral Neuropathy

Abstract

Objective: Evaluation of hepatitis C virus (HCV) by reverse transcription‐polymerase chain reaction (RT‐PCR) in peripheral nerve tissues from HCV infected patients with peripheral neuropathy. METHODS: RT‐PCR was performed on homogenates of nerve biopsies from 17 consecutive HCV‐positive patients with peripheral neuropathy, with or without mixed cryoglobulinemia, hospitalised from 1996 to 2000. Sural nerve specimens were frozen in iso‐pentane pre‐cooled in liquid nitrogen and stored at −80°C until use. RNA was extracted from ten 7‐μm thick cryostatic sections or from a nerve trunk specimen of about 3 mm length, collected from each biopsy. Three different protocols of RNA extraction were tested (1–3). Complementary DNAs (cDNAs) were obtained without or with RNasin (Promega, Madison, WI) addition in the reaction mixture to inhibit residual RNase activity. Two sets of commercially available PCR primers for the outer and the nested reaction were used. PCR products were analysed by agarose gel electrophoresis and ethidium bromide staining. Serum samples and liver specimens from proven HCV positive patients served as positive controls, whereas sera from healthy subjects were negative controls. RESULTS: Sufficient amount of RNA could be obtained either by cryostatic sections or by in toto nerve specimens. Extraction by Trizol (Gibco‐BRL) allowed the best concentration and purity of RNA as assessed by biophotometry. The presence of RNasin didn't improve the cDNA synthesis. The resulting amplification product of the nested PCR was 187 bp long. We have always observed this product in our positive controls and never in the negative. Six samples from patients either with or without cryoglobulinemia resulted positive; 7 were negative. Four samples gave variable results. CONCLUSIONS: While 40% of the nerves in our series were undoubtedly HCV positive, the cause(s) of negative and variable results in the remaining samples is likely more complex than variations in the detection protocols and deserve further investigations. REFERENCES: 1) Chomczynski P, Sacchi N (1987). Anal Biochem 162:156. 2) Marquardt O et al. (1996). Med Microbiol Lett 5:55. 3) Chomczynski P (1993). Bio/Techniques 15:532.