X4-tropic human immunodeficiency virus IIIB utilizes CXCR4 as coreceptor, as distinct from R5X4-tropic viruses

Authors

  • Salequl Islam,

    Corresponding author
    1. Department of Microbiology, Jahangirnagar University, Savar, Dhaka-1342
    • Department of Virology and Preventive Medicine, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma-371-8511
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  • Sheikh Ariful Hoque,

    1. Department of Virology and Preventive Medicine, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma-371-8511
    2. Cell and Tissue Culture Laboratory, Centre for Advanced Research in Sciences, University of Dhaka, Dhaka, Bangladesh
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  • Nihad Adnan,

    1. Department of Microbiology, Jahangirnagar University, Savar, Dhaka-1342
    2. Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Tokyo
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  • Atsushi Tanaka,

    1. Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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  • Atsushi Jinno-Oue,

    1. Department of Virology and Preventive Medicine, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma-371-8511
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  • Hiroo Hoshino

    1. Department of Virology and Preventive Medicine, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma-371-8511
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Correspondence

Salequl Islam, Department of Microbiology, Jahangirnagar University, Savar, Dhaka-1342, Bangladesh.

Tel: +88 01715 029136; fax: +88 02779 1052; email: salequl@gmail.com

ABSTRACT

Human immunodeficiency viruses initiate infections via CCR5 coreceptors and then change their tropism to C-X-C chemokine receptor type 4 (CXCR4), this change being associated with rapid disease progression. HIV-1IIIB, a widely described pure X4-tropic strain, is distinct from R5X4-tropic viruses. In this study, the requirement for amino terminal regions (NTRs) of CXCR4 for entry of HIV-1IIIB virus into host cells was examined and compared to that of R5X4-tropic viruses. CXCR4 and its deletion mutant (CXCR4ΔNTR23; first 23 amino acids removed from NTR) were amplified to examine their coreceptor activities. NP-2/CD4/CXCR4 and NP-2/CD4/CXCR4ΔNTR23 cell lines were prepared accordingly. Indirect immune fluorescence assay (IFA), PCR, and reverse transcriptase (RT) activity were used to compare the process of infection of host cells by HIV-1IIIB virus, one R5-tropic and five other R5X4-tropic viruses. All the R5X4-tropic HIVs were found to utilize both CCR5 and CXCR4 but unable to use CXCR4ΔNTR23 as coreceptors. In contrast, X4-tropic HIV-1IIIB was found to preferentially infect through CXCR4ΔNTR23. Viral antigens in infected NP-2/CD4/CXCR4ΔNTR23 cells were detected by IFA and confirmed by detection of proviral DNA and by performing RT assays on the spent cell-supernatants. In dual tropic viruses, deletion of 23 amino acids from NTR abrogates the coreceptor activity of CXCR4. This observation demonstrates that NTR of CXCR4 have an obligatory coreceptor role for dual tropic viruses. However, HIV-1IIIB may have different requirements for NTR than R5X4 viruses or may infect host cells independent of NTR of CXCR4.

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