Brief Reports
Copyright ©The Author(s) 2005. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Sep 7, 2005; 11(33): 5203-5208
Published online Sep 7, 2005. doi: 10.3748/wjg.v11.i33.5203
Flow cytometric detection of hepatitis C virus antigens in infected peripheral blood leukocytes: Binding and entry
Mostafa K El-Awady, Ashraf A Tabll, El-Rashdy M Redwan, Samar Youssef, Moataza H Omran, Fouad Thakeb, Maha El-Demellawy
Mostafa K El-Awady, Ashraf A Tabll, Samar Youssef, Moataza H Omran, Department of Biomedical Technology, National Research Center, Tahrir Street, Dokki, Cairo, Egypt
El-Rashdy M Redwan, Maha El-Demellawy, Genetic Engineering and Biotechnology Research Institute, New Borg El-Arab City, Alexandria, Egypt
Fouad Thakeb, Department of Gastroenterology-Hepatology, Faculty of Medicine Cairo University, Egypt
Author contributions: All authors contributed equally to the work.
Correspondence to: Dr. Mostafa K El-Awady, Department of Biomedical Technology, National Research Center, Tahrir Street, PO 12622, Dokki, Cairo, Egypt. mkawady@yahoo.com
Telephone: +2-2-3362609 Fax: +2-2-3370931
Received: November 23, 2004
Revised: December 5, 2004
Accepted: December 8, 2004
Published online: September 7, 2005
Abstract

AIM: We designed two synthetic-core-specific peptides core 1 (C1) and core 2 (C2), and an E1-specific peptide (E1). We produced specific polyclonal antibodies against these peptides and used the antibodies for detection of HCV antigens on surface and within infected peripheral blood leukocytes.

METHODS: Peripheral blood from a healthy individual who tested negative for HCV RNA was incubated with HCV type 4 infected serum for 1 h and 24 h at 37 °C. Cells were stained by direct and indirect immunofluorescence and measured by flow cytometry.

RESULTS: After 1 h of incubation, antibodies against C1, C2, and E1 detected HCV antigens on the surface of 27%, 26% and 73% of monocytes respectively, while 10%, 5% and 9% of lymphocytes were positive with anti-C1, anti-C2 and anti-E1 respectively. Only 1-3% of granulocytes showed positive staining with anti-C1, anti-C2 and anti E1 antibodies. After 24 h of incubation, we found no surface staining with anti-C1, anti-C2 or anti-E1. Direct immunostaining using anti-C2 could not detect intracellular HCV antigens, after 1 h of incubation with the virus, while after 24 h of incubation, 28% of infected cells showed positive staining. Only plus strand RNA was detectable intracellularly as early as 1 h after incubation, and remained detectable throughout 48 h post-infection. Interestingly, minus RNA strand could not be detected after 1 h, but became strongly detectable intracellularly after 24 h post-infection.

CONCLUSION: Monocytes and lymphocytes are the preferred target cells for HCV infection in peripheral blood leukocytes. Our specific anti-core and anti-E1 antibodies are valuable reagents for demonstration of HCV cell cycle. Also, HCV is capable of infecting and replicating in peripheral blood mononuclear cells as confirmed by detection of minus strand HCV RNA as well as intracellular staining of core HCV antigen.

Keywords: Flow cytometry; Hepatitis C virus; Envelope; Core; Antibodies; Indirect immunofluorescence; Minus and plus RNA strand; Peripheral blood mononuclear cells