Abstract
One of the phenotypic distinctions between different strains of human immunodeficiency virus type 1 (HIV-1) has to do with the ability to cause target cells to form large multinucleate bodies known as syncytia. There are two phenotypes according to this characterization: syncytium-inducing (SI) and non-syncytium-inducing (NSI). NSI strains are usually present throughout infection, while SI strains are typically seen at the beginning of the infection and near the onset of AIDS. The late emergence of SI strains is referred to as phenotype switching. In this paper we analyse the factors that lead to phenotype switching and contribute to the dynamics of disease progression. We show that a strong immune system selects for NSI strains while a weak immune system favours SI strains. The model explicitly accounts for the fact that CD4+ cells are both targets of HIV infection and crucial for activating immune responses against HIV In such a model, SI strains can emerge after a long and variable period of NSI dominated infection. Furthermore, versions of the model which do not explicitly account for HIV-specific, activated CD4+ cells do not exhibit phenotype switching, emphasizing the critical importance of this pool of cells.
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- Anzala O. A., Nagelkerke N. J., Bwayo J. J., Holton D., Moses S., Ngugi E. N., Ndinya-Achola J. O., Plummer F. A. Rapid progression to disease in African sex workers with human immunodeficiency virus type 1 infection. J Infect Dis. 1995 Mar;171(3):686–689. doi: 10.1093/infdis/171.3.686. [DOI] [PubMed] [Google Scholar]
- Baur A., Schwarz N., Ellinger S., Korn K., Harrer T., Mang K., Jahn G. Continuous clearance of HIV in a vertically infected child. Lancet. 1989 Oct 28;2(8670):1045–1045. doi: 10.1016/s0140-6736(89)91061-1. [DOI] [PubMed] [Google Scholar]
- Berger E. A. HIV entry and tropism: the chemokine receptor connection. AIDS. 1997;11 (Suppl A):S3–16. [PubMed] [Google Scholar]
- Bonhoeffer S., Coffin J. M., Nowak M. A. Human immunodeficiency virus drug therapy and virus load. J Virol. 1997 Apr;71(4):3275–3278. doi: 10.1128/jvi.71.4.3275-3278.1997. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bonhoeffer S., Holmes E. C., Nowak M. A. Causes of HIV diversity. Nature. 1995 Jul 13;376(6536):125–125. doi: 10.1038/376125a0. [DOI] [PubMed] [Google Scholar]
- Bou-Habib D. C., Roderiquez G., Oravecz T., Berman P. W., Lusso P., Norcross M. A. Cryptic nature of envelope V3 region epitopes protects primary monocytotropic human immunodeficiency virus type 1 from antibody neutralization. J Virol. 1994 Sep;68(9):6006–6013. doi: 10.1128/jvi.68.9.6006-6013.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Boucher C. A., Reedijk M. Viral resistance: a major challenge in managing HIV disease. J Biol Regul Homeost Agents. 1995 Jul-Sep;9(3):91–94. [PubMed] [Google Scholar]
- Bukrinsky M. I., Stanwick T. L., Dempsey M. P., Stevenson M. Quiescent T lymphocytes as an inducible virus reservoir in HIV-1 infection. Science. 1991 Oct 18;254(5030):423–427. doi: 10.1126/science.1925601. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Coffin J. M. HIV population dynamics in vivo: implications for genetic variation, pathogenesis, and therapy. Science. 1995 Jan 27;267(5197):483–489. doi: 10.1126/science.7824947. [DOI] [PubMed] [Google Scholar]
- Connor R. I., Mohri H., Cao Y., Ho D. D. Increased viral burden and cytopathicity correlate temporally with CD4+ T-lymphocyte decline and clinical progression in human immunodeficiency virus type 1-infected individuals. J Virol. 1993 Apr;67(4):1772–1777. doi: 10.1128/jvi.67.4.1772-1777.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cornelissen M., Mulder-Kampinga G., Veenstra J., Zorgdrager F., Kuiken C., Hartman S., Dekker J., van der Hoek L., Sol C., Coutinho R. Syncytium-inducing (SI) phenotype suppression at seroconversion after intramuscular inoculation of a non-syncytium-inducing/SI phenotypically mixed human immunodeficiency virus population. J Virol. 1995 Mar;69(3):1810–1818. doi: 10.1128/jvi.69.3.1810-1818.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
- De Jong J. J., De Ronde A., Keulen W., Tersmette M., Goudsmit J. Minimal requirements for the human immunodeficiency virus type 1 V3 domain to support the syncytium-inducing phenotype: analysis by single amino acid substitution. J Virol. 1992 Nov;66(11):6777–6780. doi: 10.1128/jvi.66.11.6777-6780.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fauci A. S. Host factors and the pathogenesis of HIV-induced disease. Nature. 1996 Dec 12;384(6609):529–534. doi: 10.1038/384529a0. [DOI] [PubMed] [Google Scholar]
- Fouchier R. A., Groenink M., Kootstra N. A., Tersmette M., Huisman H. G., Miedema F., Schuitemaker H. Phenotype-associated sequence variation in the third variable domain of the human immunodeficiency virus type 1 gp120 molecule. J Virol. 1992 May;66(5):3183–3187. doi: 10.1128/jvi.66.5.3183-3187.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fouchier R. A., Meyaard L., Brouwer M., Hovenkamp E., Schuitemaker H. Broader tropism and higher cytopathicity for CD4+ T cells of a syncytium-inducing compared to a non-syncytium-inducing HIV-1 isolate as a mechanism for accelerated CD4+ T cell decline in vivo. Virology. 1996 May 1;219(1):87–95. doi: 10.1006/viro.1996.0225. [DOI] [PubMed] [Google Scholar]
- Gartner S., Markovits P., Markovitz D. M., Kaplan M. H., Gallo R. C., Popovic M. The role of mononuclear phagocytes in HTLV-III/LAV infection. Science. 1986 Jul 11;233(4760):215–219. doi: 10.1126/science.3014648. [DOI] [PubMed] [Google Scholar]
- Goulder P. J., Phillips R. E., Colbert R. A., McAdam S., Ogg G., Nowak M. A., Giangrande P., Luzzi G., Morgan B., Edwards A. Late escape from an immunodominant cytotoxic T-lymphocyte response associated with progression to AIDS. Nat Med. 1997 Feb;3(2):212–217. doi: 10.1038/nm0297-212. [DOI] [PubMed] [Google Scholar]
- Grivel J. C., Margolis L. B. CCR5- and CXCR4-tropic HIV-1 are equally cytopathic for their T-cell targets in human lymphoid tissue. Nat Med. 1999 Mar;5(3):344–346. doi: 10.1038/6565. [DOI] [PubMed] [Google Scholar]
- Groenink M., Fouchier R. A., de Goede R. E., de Wolf F., Gruters R. A., Cuypers H. T., Huisman H. G., Tersmette M. Phenotypic heterogeneity in a panel of infectious molecular human immunodeficiency virus type 1 clones derived from a single individual. J Virol. 1991 Apr;65(4):1968–1975. doi: 10.1128/jvi.65.4.1968-1975.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Haas G., Plikat U., Debré P., Lucchiari M., Katlama C., Dudoit Y., Bonduelle O., Bauer M., Ihlenfeldt H. G., Jung G. Dynamics of viral variants in HIV-1 Nef and specific cytotoxic T lymphocytes in vivo. J Immunol. 1996 Nov 1;157(9):4212–4221. [PubMed] [Google Scholar]
- Haynes B. F., Pantaleo G., Fauci A. S. Toward an understanding of the correlates of protective immunity to HIV infection. Science. 1996 Jan 19;271(5247):324–328. doi: 10.1126/science.271.5247.324. [DOI] [PubMed] [Google Scholar]
- Herbein G., Mahlknecht U., Batliwalla F., Gregersen P., Pappas T., Butler J., O'Brien W. A., Verdin E. Apoptosis of CD8+ T cells is mediated by macrophages through interaction of HIV gp120 with chemokine receptor CXCR4. Nature. 1998 Sep 10;395(6698):189–194. doi: 10.1038/26026. [DOI] [PubMed] [Google Scholar]
- Ho D. D., Neumann A. U., Perelson A. S., Chen W., Leonard J. M., Markowitz M. Rapid turnover of plasma virions and CD4 lymphocytes in HIV-1 infection. Nature. 1995 Jan 12;373(6510):123–126. doi: 10.1038/373123a0. [DOI] [PubMed] [Google Scholar]
- Kalams S. A., Walker B. D. The critical need for CD4 help in maintaining effective cytotoxic T lymphocyte responses. J Exp Med. 1998 Dec 21;188(12):2199–2204. doi: 10.1084/jem.188.12.2199. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Koenig S., Gendelman H. E., Orenstein J. M., Dal Canto M. C., Pezeshkpour G. H., Yungbluth M., Janotta F., Aksamit A., Martin M. A., Fauci A. S. Detection of AIDS virus in macrophages in brain tissue from AIDS patients with encephalopathy. Science. 1986 Sep 5;233(4768):1089–1093. doi: 10.1126/science.3016903. [DOI] [PubMed] [Google Scholar]
- Koot M., van 't Wout A. B., Kootstra N. A., de Goede R. E., Tersmette M., Schuitemaker H. Relation between changes in cellular load, evolution of viral phenotype, and the clonal composition of virus populations in the course of human immunodeficiency virus type 1 infection. J Infect Dis. 1996 Feb;173(2):349–354. doi: 10.1093/infdis/173.2.349. [DOI] [PubMed] [Google Scholar]
- Koot M., van Leeuwen R., de Goede R. E., Keet I. P., Danner S., Eeftinck Schattenkerk J. K., Reiss P., Tersmette M., Lange J. M., Schuitemaker H. Conversion rate towards a syncytium-inducing (SI) phenotype during different stages of human immunodeficiency virus type 1 infection and prognostic value of SI phenotype for survival after AIDS diagnosis. J Infect Dis. 1999 Jan;179(1):254–258. doi: 10.1086/314539. [DOI] [PubMed] [Google Scholar]
- Koup R. A., Safrit J. T., Cao Y., Andrews C. A., McLeod G., Borkowsky W., Farthing C., Ho D. D. Temporal association of cellular immune responses with the initial control of viremia in primary human immunodeficiency virus type 1 syndrome. J Virol. 1994 Jul;68(7):4650–4655. doi: 10.1128/jvi.68.7.4650-4655.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Loveday C., Kaye S., Tenant-Flowers M., Semple M., Ayliffe U., Weller I. V., Tedder R. S. HIV-1 RNA serum-load and resistant viral genotypes during early zidovudine therapy. Lancet. 1995 Apr 1;345(8953):820–824. doi: 10.1016/s0140-6736(95)92963-0. [DOI] [PubMed] [Google Scholar]
- Mackewicz C. E., Ortega H. W., Levy J. A. CD8+ cell anti-HIV activity correlates with the clinical state of the infected individual. J Clin Invest. 1991 Apr;87(4):1462–1466. doi: 10.1172/JCI115153. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McLean A. R., Kirkwood T. B. A model of human immunodeficiency virus infection in T helper cell clones. J Theor Biol. 1990 Nov 21;147(2):177–203. doi: 10.1016/s0022-5193(05)80051-7. [DOI] [PubMed] [Google Scholar]
- McLean A. R., Nowak M. A. Models of interactions between HIV and other pathogens. J Theor Biol. 1992 Mar 7;155(1):69–86. doi: 10.1016/s0022-5193(05)80549-1. [DOI] [PubMed] [Google Scholar]
- McMichael A. J., O'Callaghan C. A. A new look at T cells. J Exp Med. 1998 May 4;187(9):1367–1371. doi: 10.1084/jem.187.9.1367. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mellors J. W., Rinaldo C. R., Jr, Gupta P., White R. M., Todd J. A., Kingsley L. A. Prognosis in HIV-1 infection predicted by the quantity of virus in plasma. Science. 1996 May 24;272(5265):1167–1170. doi: 10.1126/science.272.5265.1167. [DOI] [PubMed] [Google Scholar]
- Miedema F., Meyaard L., Koot M., Klein M. R., Roos M. T., Groenink M., Fouchier R. A., Van't Wout A. B., Tersmette M., Schellekens P. T. Changing virus-host interactions in the course of HIV-1 infection. Immunol Rev. 1994 Aug;140:35–72. doi: 10.1111/j.1600-065x.1994.tb00864.x. [DOI] [PubMed] [Google Scholar]
- Nagelkerke N. J., Plummer F. A., Holton D., Anzala A. O., Manji F., Ngugi E. N., Moses S. Transition dynamics of HIV disease in a cohort of African prostitutes: a Markov model approach. AIDS. 1990 Aug;4(8):743–747. doi: 10.1097/00002030-199008000-00005. [DOI] [PubMed] [Google Scholar]
- Nowak M. A., Anderson R. M., McLean A. R., Wolfs T. F., Goudsmit J., May R. M. Antigenic diversity thresholds and the development of AIDS. Science. 1991 Nov 15;254(5034):963–969. doi: 10.1126/science.1683006. [DOI] [PubMed] [Google Scholar]
- Nowak M. A., May R. M. Mathematical biology of HIV infections: antigenic variation and diversity threshold. Math Biosci. 1991 Sep;106(1):1–21. doi: 10.1016/0025-5564(91)90037-j. [DOI] [PubMed] [Google Scholar]
- Ogg G. S., Jin X., Bonhoeffer S., Dunbar P. R., Nowak M. A., Monard S., Segal J. P., Cao Y., Rowland-Jones S. L., Cerundolo V. Quantitation of HIV-1-specific cytotoxic T lymphocytes and plasma load of viral RNA. Science. 1998 Mar 27;279(5359):2103–2106. doi: 10.1126/science.279.5359.2103. [DOI] [PubMed] [Google Scholar]
- Ostrowski M. A., Krakauer D. C., Li Y., Justement S. J., Learn G., Ehler L. A., Stanley S. K., Nowak M., Fauci A. S. Effect of immune activation on the dynamics of human immunodeficiency virus replication and on the distribution of viral quasispecies. J Virol. 1998 Oct;72(10):7772–7784. doi: 10.1128/jvi.72.10.7772-7784.1998. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pantaleo G., Fauci A. S. Immunopathogenesis of HIV infection. Annu Rev Microbiol. 1996;50:825–854. doi: 10.1146/annurev.micro.50.1.825. [DOI] [PubMed] [Google Scholar]
- Perelson A. S., Neumann A. U., Markowitz M., Leonard J. M., Ho D. D. HIV-1 dynamics in vivo: virion clearance rate, infected cell life-span, and viral generation time. Science. 1996 Mar 15;271(5255):1582–1586. doi: 10.1126/science.271.5255.1582. [DOI] [PubMed] [Google Scholar]
- Phair J. P. Keynote address: variations in the natural history of HIV infection. AIDS Res Hum Retroviruses. 1994 Aug;10(8):883–885. doi: 10.1089/aid.1994.10.883. [DOI] [PubMed] [Google Scholar]
- Pratt R. D., Shapiro J. F., McKinney N., Kwok S., Spector S. A. Virologic characterization of primary human immunodeficiency virus type 1 infection in a health care worker following needlestick injury. J Infect Dis. 1995 Sep;172(3):851–854. doi: 10.1093/infdis/172.3.851. [DOI] [PubMed] [Google Scholar]
- Price D. A., Goulder P. J., Klenerman P., Sewell A. K., Easterbrook P. J., Troop M., Bangham C. R., Phillips R. E. Positive selection of HIV-1 cytotoxic T lymphocyte escape variants during primary infection. Proc Natl Acad Sci U S A. 1997 Mar 4;94(5):1890–1895. doi: 10.1073/pnas.94.5.1890. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Quinn T. C., Piot P., McCormick J. B., Feinsod F. M., Taelman H., Kapita B., Stevens W., Fauci A. S. Serologic and immunologic studies in patients with AIDS in North America and Africa. The potential role of infectious agents as cofactors in human immunodeficiency virus infection. JAMA. 1987 May 15;257(19):2617–2621. [PubMed] [Google Scholar]
- Ribeiro R. M., Bonhoeffer S., Nowak M. A. The frequency of resistant mutant virus before antiviral therapy. AIDS. 1998 Mar 26;12(5):461–465. doi: 10.1097/00002030-199805000-00006. [DOI] [PubMed] [Google Scholar]
- Roos M. T., Lange J. M., de Goede R. E., Coutinho R. A., Schellekens P. T., Miedema F., Tersmette M. Viral phenotype and immune response in primary human immunodeficiency virus type 1 infection. J Infect Dis. 1992 Mar;165(3):427–432. doi: 10.1093/infdis/165.3.427. [DOI] [PubMed] [Google Scholar]
- Rosenberg E. S., Billingsley J. M., Caliendo A. M., Boswell S. L., Sax P. E., Kalams S. A., Walker B. D. Vigorous HIV-1-specific CD4+ T cell responses associated with control of viremia. Science. 1997 Nov 21;278(5342):1447–1450. doi: 10.1126/science.278.5342.1447. [DOI] [PubMed] [Google Scholar]
- Rosenberg E. S., Walker B. D. HIV type 1-specific helper T cells: a critical host defense. AIDS Res Hum Retroviruses. 1998 Jun;14 (Suppl 2):S143–S147. [PubMed] [Google Scholar]
- Safrit J. T., Koup R. A. The immunology of primary HIV infection: which immune responses control HIV replication? Curr Opin Immunol. 1995 Aug;7(4):456–461. doi: 10.1016/0952-7915(95)80088-3. [DOI] [PubMed] [Google Scholar]
- Schuitemaker H., Koot M., Kootstra N. A., Dercksen M. W., de Goede R. E., van Steenwijk R. P., Lange J. M., Schattenkerk J. K., Miedema F., Tersmette M. Biological phenotype of human immunodeficiency virus type 1 clones at different stages of infection: progression of disease is associated with a shift from monocytotropic to T-cell-tropic virus population. J Virol. 1992 Mar;66(3):1354–1360. doi: 10.1128/jvi.66.3.1354-1360.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Stevenson M. Portals of entry: uncovering HIV nuclear transport pathways. Trends Cell Biol. 1996 Jan;6(1):9–15. doi: 10.1016/0962-8924(96)81032-4. [DOI] [PubMed] [Google Scholar]
- Tersmette M., Gruters R. A., de Wolf F., de Goede R. E., Lange J. M., Schellekens P. T., Goudsmit J., Huisman H. G., Miedema F. Evidence for a role of virulent human immunodeficiency virus (HIV) variants in the pathogenesis of acquired immunodeficiency syndrome: studies on sequential HIV isolates. J Virol. 1989 May;63(5):2118–2125. doi: 10.1128/jvi.63.5.2118-2125.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wei X., Ghosh S. K., Taylor M. E., Johnson V. A., Emini E. A., Deutsch P., Lifson J. D., Bonhoeffer S., Nowak M. A., Hahn B. H. Viral dynamics in human immunodeficiency virus type 1 infection. Nature. 1995 Jan 12;373(6510):117–122. doi: 10.1038/373117a0. [DOI] [PubMed] [Google Scholar]
- Wodarz D., Lloyd A. L., Jansen V. A., Nowak M. A. Dynamics of macrophage and T cell infection by HIV. J Theor Biol. 1999 Jan 7;196(1):101–113. doi: 10.1006/jtbi.1998.0816. [DOI] [PubMed] [Google Scholar]
- Wodarz D., Nowak M. A. The effect of different immune responses on the evolution of virulent CXCR4-tropic HIV. Proc Biol Sci. 1998 Nov 22;265(1411):2149–2158. doi: 10.1098/rspb.1998.0552. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zhu T., Mo H., Wang N., Nam D. S., Cao Y., Koup R. A., Ho D. D. Genotypic and phenotypic characterization of HIV-1 patients with primary infection. Science. 1993 Aug 27;261(5125):1179–1181. doi: 10.1126/science.8356453. [DOI] [PubMed] [Google Scholar]
- van't Wout A. B., Kootstra N. A., Mulder-Kampinga G. A., Albrecht-van Lent N., Scherpbier H. J., Veenstra J., Boer K., Coutinho R. A., Miedema F., Schuitemaker H. Macrophage-tropic variants initiate human immunodeficiency virus type 1 infection after sexual, parenteral, and vertical transmission. J Clin Invest. 1994 Nov;94(5):2060–2067. doi: 10.1172/JCI117560. [DOI] [PMC free article] [PubMed] [Google Scholar]