Dutch vaccines developer Intravacc has reported positive results from the Phase I clinical trial of its respiratory syncytial virus (RSV) vaccine candidate.

The vaccine candidate was observed to trigger immunogenicity following nasal administration in healthy adults aged 18 to 50. Investigators also reported the candidate to be safe and well-tolerated.

Intravacc’s RSV candidate is a live attenuated vaccine (LAV) made with reverse genetics, without the G (adhesion) protein.

The randomised, placebo-controlled Phase I trial was conducted to assess the safety, tolerability, excretion and immunogenicity of the vaccine.

In preclinical studies, RSVDG led to a reduction in host cell binding and infectivity.

Intranasal immunisation of the RSVDG vaccine in laboratory animals also showed protection against replication of wild-type RSV, without disease aggravation.

An RSV without the G-protein is expected to be attenuated and induce an effective immune response because of the surface protein F as the major antigen site and residual infectivity.

During the Phase I trial, participants were given one dose of vaccine intranasally compared to a placebo.

The side effects of the vaccine were mild and comparable to the placebo group. After administration, no measurable amounts of vaccine were excreted according to the company.

Measured antibody levels were reported to be comparable before and after immunisation, as well as between vaccine and placebo arms.

Intravacc CEO Dr Jan Groen said: “Although the development of an RSV vaccine is very complex, our live attenuated vaccine provides an important first step in the clinical development of an ultimately effective vaccine.

“We look forward to working with targeted industry partners for the further joint development of this promising vaccine.”

Intravacc is currently seeking a partner for joint clinical development of this vaccine in a large paediatric setting.