Viral dynamics during primary simian immunodeficiency virus infection: Effect of time-dependent virus infectivity

Naveen K. Vaidya, Ruy M. Ribeiro, Chris J Miller, Alan S. Perelson

Research output: Contribution to journalArticle

34 Scopus citations


A recent experiment involving simian immunodeficiency virus (SIV) infection of macaques revealed that the infectivity of this virus decreased over the first few months of infection. Based on this observation, we introduce a viral dynamic model in which viral infectivity varies over time. The model is fit to viral load data from eight (donor) monkeys infected by intravaginal inoculation of SIVmac251, three monkeys infected by intravenous inoculation of virus isolated from the donors during the ramp-up phase of acute infection, and three monkeys infected by intravenous inoculation of virus isolated at the viral set-point. Although we only analyze data from 14 monkeys, the new model with time-dependent infectivity seems to fit the data significantly better than a widely used model with constant infectivity (P = 2.44 × 10-11). Our results indicate that plasma virus infectivity on average decays ∼8-fold (95% confidence interval [CI] = 5.1 to 10.3) over the course of acute infection, with the decay occurring exponentially with an average rate of 0.28 day-1 (95% CI = 0.14 to 0.42 day-1). The decay rate in set point plasma virus recipient animals is ∼16 times slower than in ramp-up plasma virus recipient animals and ∼6 times slower than in donor animals. Throughout acute infection up to the set-point, the infection rate is higher in ramp-up plasma virus recipient animals than in set-point plasma virus recipient animals. These results show that the infectivity depends upon the source of viral infection.

Original languageEnglish (US)
Pages (from-to)4302-4310
Number of pages9
JournalJournal of Virology
Issue number9
StatePublished - May 2010


ASJC Scopus subject areas

  • Immunology
  • Virology

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