High specific infectivity of plasma virus from the pre-ramp-up and ramp-up stages of acute simian immunodeficiency virus infection

Zhong Min Ma, Mars Stone, Mike Piatak, Becky Schweighardt, Nancy L. Haigwood, David Montefiori, Jeffrey D. Lifson, Michael P. Busch, Christopher J. Miller

    Research output: Contribution to journalArticlepeer-review

    79 Scopus citations


    To define the ratio of simian immunodeficiency virus (SIV) RNA molecules to infectious virions in plasma, a ramp-up-stage plasma pool was made from the earliest viral RNA (vRNA)-positive plasma samples (collected approximately 7 days after inoculation) from seven macaques, and a set-point-stage plasma pool was made from plasma samples collected 10 to 16 weeks after peak viremia from seven macaques; vRNA levels in these plasma pools were determined, and serial 10-fold dilutions containing 1 to 1,500 vRNA copies/ml were made. Intravenous (i.v.) inoculation of a 1-ml aliquot of diluted ramp-up-stage plasma containing 20 vRNA copies infected 2 of 2 rhesus macaques, while for the set-point-stage plasma, i.v. inoculation with 1,500 vRNA copies was needed to transmit infection. Further, when the heat-inactivated set-point-stage plasma pool was mixed with ramp-up-stage virions, infection of inoculated macaques was blocked. Notably, 2 of 2 animals inoculated with 85 ml of a pre-ramp-up plasma pool containing <3 SIV RNA copies/ml developed SIV infections characterized by high levels of viral replication, demonstrating that "vRNA-negative" plasma collected from macaques in the pre-ramp-up stage is infectious. Furthermore, there is a high ratio of infectious virions to total virions in ramp-up-stage plasma (between 1:1 and 1:10) and a lower ratio in set-point-stage plasma (between 1:75 and 1:750). Heat-inactivated chronic-stage plasma can "neutralize" the highly infectious ramp-up-stage virions. These findings have implications for the understanding of the natural history of SIV and human immunodeficiency virus infection and transmission.

    Original languageEnglish (US)
    Pages (from-to)3288-3297
    Number of pages10
    JournalJournal of virology
    Issue number7
    StatePublished - Apr 2009

    ASJC Scopus subject areas

    • Microbiology
    • Immunology
    • Insect Science
    • Virology


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