Multiple immunizations with adenovirus and MVA vectors improve CD8+ T cell functionality and mucosal homing

Area of Science:

• Immunology
• Vaccinology
• Viral Vector Technology

Background:

• Prime-boost vaccine regimens are critical for enhancing adaptive immune responses.
• Understanding the impact of repeated immunizations on T cell dynamics is essential for effective vaccine design.

Purpose of the Study:

• To evaluate the effect of prime-boost vaccination strategies using recombinant adenovirus and modified vaccinia Ankara (MVA) vectors on transgene product-specific CD8(+) T cell responses.
• To assess the impact of repeated immunizations on T cell frequencies, phenotypes, function, and localization.

Main Methods:

• Utilized recombinant adenovirus vectors (human adenovirus serotype 5, chimpanzee-derived adenoviruses serotype 68 or 7) and MVA vectors in prime-boost vaccine regimens.
• Administered triple immunizations to assess immune cell responses.

Main Results:

• A three-dose immunization regimen incorporating MVA and specific adenoviruses significantly increased transgene product-specific CD8(+) T cell frequencies in spleen, blood, lymph nodes, and peritoneal lavage.
• Triple immunization led to increased frequencies of transgene-specific T cells at mucosal sites, including mesenteric lymph nodes, intestinal epithelium, and Peyer's patches.

Conclusions:

• Multiple-dose vaccine regimens employing MVA and adenovirus vectors can markedly increase functionally active transgene-specific CD8(+) T cells.
• Targeting T cells to appropriate ports of entry through optimized vaccination schedules may be vital for protection against pathogens like HIV-1.