475 Modeling of Host Transcription during Acute HIV Infection Using SHIV-infected Cynomolgus Macaques S E Bosinger*1,2, M J Cameron2, K A Hosiawa1,2, D Persad1,2, L Ran2, E W Rud3, D K Kelvin2 1Univ of Western Ontario, London, Canada; 2Univ Hlth Network, Toronto, Canada; and 3Natl Lab for HIV Pathogenesis, Hlth Canada, Ottawa
Background: HIV modulates the expression of a vast array of host genes that drive pathogenesis. In order to better understand HIV pathogenesis macaques infected with SHIV89.6P were examined during acute infection using high density microarray. Hypothesis: Host expression during the period of severe CD4+ T-cell reduction will be reflective of the depletion mechanism.
Methods: Four (4) cynomolgus macaques were infected with SHIV89.6P. Viral load and CD4+ levels were monitored in whole blood over the first 5-weeks of infection. Alterations in host expression were analyzed using a 19, 200 element cDNA microarray. Eight (8) replicate microarray measurements were taken per interval. Gene expression changes were statistically validated using a modified t-test that allowed detection of significantly changed. Only genes found to differentially expressed at a significance of p < 0.02, and a fold-change of > 2 were used for downstream modeling. Partitional clustering (k-means = 8) identified coordinately regulated gene families.
Results: CD4+ levels increased 2-fold at wk 1 post-infection (pi), but declined below pre-infection levels by wk 2 for the remainder of the 5 weeks. Similarly, plasma viral load increased sharply after 1 wk infection, peaked at wk 2 ,but dropped sharply again after wks 4 and 5, respectively. Whole blood RNA was extracted at each interval and compared with RNA extracted at day 0. After 1 wk of SHIV infection, 3,840 genes were found to be significantly (p < 0.02) differentially expressed, and 2502, 5251, and 3231 differential genes were observed after 2, 4, and 5 wks pi, respectively. Partitional clustering (k = 6) revealed families of genes that were similarly regulated. Real-time PCR was used to confirm the microarray data.
Conclusions: At 2 wks pi, the interval at which maximal CD4+ cell death occurs, upregulation of several tumour necrosis factor associated factor (TRAF) genes: TRIP, TRAF1, and AD022 was observed, providing support for a current model of CD4+ depletion via an overexpression of FAS and related components. Several interferon response genes (ISGs) (Mx1/2, OAS1/3, IFI16, SCYB10, GBP2, G1P3) were part of cluster over-expressed over all intervals; however, a family of ISGs was suppressed. Finally, TLR4, CD14 and several mediators of leukotriene synthesis were part of a family of severely suppressed genes, suggesting a mechanism by which immunodeficiency to bacteria may occur in the context of AIDS.
