1. ¹Children's Hospital Boston, Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
2. ²Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
3. ³Gene Therapy Program, Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
4. ⁴Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
5. ⁵New England Regional Primate Research Center, Department of Pathology, Harvard Medical School, Southborough, Massachusetts, USA
6. ⁶Present address: Institute of Molecular Medicine, National Cheng Kung University, College of Medicine, Tainan, Taiwan

Correspondence: A Aldovini, (anna.aldovini@childrens.harvard.edu)

Received 29 June 2009; Accepted 16 July 2009; Published online 9 September 2009.

Abstract

Preventive human immunodeficiency virus (HIV) vaccination may require induction of virus-specific immune responses at mucosal sites to contain viral infection locally after exposure, as most HIV infections occur through mucosal surfaces. We compared the efficacy of an intranasal or intramuscular Simian immunodeficiency virus (SIV)+ interleukin (IL)-2+IL-15 DNA/SIV–MVA (modified vaccinia virus Ankara) vaccination in preventing disease progression in SIVmac251 intrarectally challenged rhesus macaques. SIV-specific rectal IgA responses were more significantly persistent in nasally vaccinated than in intramuscularly vaccinated animals. No significant differences were observed in the magnitude of systemic T-cell responses between the two groups, although the nasal immunization induced more significant anti-SIV T-cell responses in the colorectal mucosa. After challenge, CD4⁺ central memory (C_M) T-cell preservation and significant disease-delay were observed in both vaccination groups. However, nasally vaccinated animals had more significant early preservation of circulating and colorectal CD4⁺ C_M T cells, of circulating CD4⁺/47⁺ effector memory (E_M) T cells, and a longer disease-free interval when compared with the intramuscularly vaccinated or control groups. Regardless of vaccination status, long-term viremia control and preservation of CD4⁺ C_M T cells was detected in animals with significantly higher systemic CD8⁺/tumor necrosis factor (TNF)-⁺ and CD8⁺/interferon (IFN)-⁺ T-cell responses and higher SIV-specific CD4⁺/IL-2⁺ responses in colorectal T cells.