Immunization with whole inactivated vaccine protects from infection by SIV grown in human but not macaque cells

Area of Science:

• Virology
• Immunology
• Vaccinology

Background:

• Simian immunodeficiency virus (SIV) infection in macaques serves as a model for human immunodeficiency virus (HIV) research.
• Developing effective SIV vaccines is crucial for advancing HIV vaccine development.
• Understanding factors influencing vaccine efficacy, such as virus preparation, is essential.

Purpose of the Study:

• To investigate the impact of SIVsm virus preparation on the efficacy of a whole inactivated SIV vaccine.
• To determine if SIV vaccine-mediated protection is species-specific.

Main Methods:

• Generation of homologous SIVsm stocks by passaging SIVsm/E660 in human (CEM x 174) or macaque peripheral blood mononuclear cells.
• Immunization of macaques with a whole inactivated SIV vaccine derived from virus produced in human cells (SIVsmH4 clone).
• Challenging immunized macaques with either cell-free SIVsm stock (human-derived or macaque-derived).

Main Results:

• Macaques vaccinated and then challenged with SIVsm generated in human cells were protected from infection.
• Macaques vaccinated and challenged with SIVsm generated in macaque cells were not protected from infection.
• Protection was observed exclusively in vaccinees challenged with virus prepared in a human cell line.

Conclusions:

• Whole inactivated SIV vaccines demonstrate species-specific protection.
• The cellular origin of the vaccine virus preparation significantly impacts its efficacy.
• These findings have implications for the design and production of SIV and potentially HIV vaccines.