RSV Vaccine Based on Rhabdoviral Vector Protects after Single Immunization

Area of Science:

• Virology
• Vaccinology
• Immunology

Background:

• Respiratory syncytial virus (RSV) causes significant childhood lower respiratory tract infections.
• An effective RSV vaccine remains unavailable, highlighting the need for novel vaccine strategies.

Purpose of the Study:

• To evaluate the VSV-GP viral vector as a vaccine candidate for inducing RSV-neutralizing antibodies.
• To assess the efficacy of VSV-GP expressing RSV F proteins against RSV challenge in a mouse model.

Main Methods:

• The VSV-GP vector was engineered to express wild-type (Fwt) or codon-optimized (Fsyn) RSV fusion (F) proteins.
• Mice were immunized with the VSV-GP-F vaccine, followed by RSV challenge.
• Viral loads in the lungs and antibody responses were quantified.

Main Results:

• VSV-GP-F efficiently expressed RSV F proteins and induced high titers of RSV-neutralizing antibodies after prime and boost immunizations.
• Vaccinated mice showed a 2-3 log reduction in lung viral loads after RSV challenge, without enhanced disease.
• A single intranasal immunization significantly reduced viral load (>100-fold), and protection was maintained for 20 weeks post-boost.

Conclusions:

• The VSV-GP vector is a promising candidate for developing an effective RSV vaccine.
• The vaccine elicits robust, long-lasting neutralizing antibody responses and provides significant protection against RSV challenge.
• Intranasal administration offers a potential route for vaccination, with single-dose efficacy demonstrated.