Cognitive Function Study On Chronic HCV Infection Patients

Objective: In present research we want to investigate: a) the difference of neuropsychological tests among mild chronic HCV infected patients, mild chronic HBV infected patients, and controls; b) the correlation between the cognitive function deficits and depression in mild chronic HCV infected patients; c) nucleic acid testing techniques for detecting hepatitis c virus (HCV) in cerebrospinal fluid using nested fluorescence quantitative reverse transcriptase polymerase chain reaction (Nested-qRT-PCR); d) cognitive impairment caused by HCV infection in the central nervous system.Methods1. 36 mild chronic HCV infected patients, 32 mild chronic HBV infected patients and 28 controls were assessed by a series of neuropsychological tests. Depression symptoms were also assessed by Beck Depression Inventory (BDI-Ⅱ).2. Specific primers and TaqMan probes were designed in the conserved region of virus genome 5'NCR. Conserved region gene contained in plasmids which is offered by Chongqing Medical University hepatitis virus laboratory was inserted into pGEM-T Easy vector and transcribed in vitro to produce RNA, which would be used as standards in PCR quantification. A nested fluorescence quantitative RT-PCR method to detect positive- and negative- strands HCV RNA is established. At the same time, sensitivity and specificity of method were assessed.3. The HCV 5'NCR fragment of peripheral blood mononuclear cells (PBMCs) and CSF obtained from 12 patients with chronic HCV infection were examined by Nested-qRT-PCR. Furthermore, molecular cloning and sequence analysis were carried out on positive PCR products. Neuropsychological tests were also performed on 12 patients with chronic HCV infection.Results1. There is a significant difference between chronic HCV infected patients and controls in neuropsychological tests. The scores of digit-symbol, delayed-logical- memory, TMT-B and Stroop tests in chronic HCV infected patients are significantly lower than those in controls. However, there is no significant difference between chronic HBV infected patients and controls in neuropsychological tests.2. The Nested-qRT-PCR methods for the detections of positive- and negative- strands HCV RNA were successfully established. The minimum detection limits of Nested-qRT-PCR for HCV are 2.6×102 copies/μl and 2.6×101 copies/μl respectively, the quantitative range of standard curve is 2.6×102 ~2.6×107 copies/μl (R2 0.9883) for positive-strand HCV RNA, and 2.6×101~2.6×107 copies/μl (R2 0.9969) for negative-strand HCV RNA. Nonspecific PCR reaction with other virus was not discovered.3. Nucleic acid detections for positive- and negative- strands HCV RNA were successfully performed on PBMCs and CSF samples from 12 patients with chronic HCV infection using Nested-qRT-PCR. Positive-strand HCV RNA was detected in three out of 12 cases of CSF and negative-strand HCV RNA in two out of 12 cases of CSF.4. Neuropsychological tests were further performed on both three HCV detected positive cases and 9 HCV detected negative ones in CSF. Significant difference was found in digit-symbol and TMT-B testing.Conclusions1. Chronic HCV infected patients perform significantly worse than healthy controls on complex visual scanning, psychomotor speed, attention and working memory. The cognitive deficits are not related to depression symptoms. Hepatitis B patients are not similarly impaired in cognitive function, suggesting that the observed abnormalities are specific.2. Nested-qRT-PCR methods for detecting N positive- and negative- strands HCV RNA has been established successfully. The methods are sensitive and reliable and allow rapid detection and quantitation of hepatitis c virus in CSF.3. The results have demonstrated that cognitive impairment in chronic HCV infected patients may be caused by the HCV infection in the central nervous system.