This study is a multicentre, randomized, placebo-controlled, fully blinded, clinical trial of twice daily oral valacyclovir 500mg versus placebo with the goal of delaying the need for initiating HAART among HIV infected individuals who neither use nor require HAART, and who have not used chronic suppressive anti-HSV therapy for at least the 6 months prior to study initiation.

Inclusion Criteria:

• adult (aged 18 years or older or as per Local/Provincial Guidelines)
• documented HIV-1 infection (determined by EIA and Western blot, sites' standard assays are acceptable if approved in advance by the PIs for the study, Dr. Darrell Tan and/or Dr. Sharon Walmsley)
• no use of chronic anti-HSV therapy for the past 6 months, and not anticipated to require chronic anti-HSV therapy during the study
• antiretroviral naïve (no more than 14 days of total prior ARV exposure)
• CD4 count within the 400-900 cells/mm3 range (inclusive) on two consecutive occasions, with at least one measurement within 30 days of initiating trial (baseline visit)
• does not meet recommendations for initiating ARV therapy according to current guidelines

Exclusion Criteria:

• pregnancy or actively planning to become pregnant
• receiving chemotherapy, chronic steroid therapy or other immunomodulatory medications (e.g. interferon, azathioprine, methotrexate, TNF-alpha antagonists, etc.)
• Estimated creatinine clearance <30 mL/min
• Other medical condition likely to cause death within 24 months
• Enrolled in a therapeutic HIV vaccine or immunotherapy trial
• Enrolled in another trial investigating the impact of another intervention on HIV disease progression
• HIV elite controller (EC), phenotypically defined here as documented duration of HIV infection of ≥5 years, a persistent CD4 cell count ≥500 cells/mm3, and a persistent plasma HIV viral load of <1000 copies/mL in the absence of antiretroviral therapy