VRX1023, our HIV-1-based lentiviral vector vaccine candidate for HIV, is the topic of a new paper authored by three of my VIRxSYS colleagues and published in the January issue of Vaccine. VRX1023 has been engineered to deliver HIV-1 Gag, Pol and Rev antigens.
In the new paper, “Heterologous HIV-based lentiviral/adenoviral vectors immunizations result in enhanced HIV-specific immunity,” our scientists report on the vaccination of mice with VRX1023 and an adenovirus serotype 5-based vector, using a “prime-boost” approach (an immunization strategy in which one vaccination is given, followed by a second vaccination at another time).
Compared to homologous prime-boost regimens (i.e. using only one type of vaccine, such as only the adenoviral-based candidate), the heterologous immunization regimen using both the lentiviral and adenoviral vector candidates dramatically improved immunogenicity, increasing the number of CD4+ and CD8+ immune cells that were specific to HIV. In addition, this combined approach did not induce high levels of anti- vector-neutralizing antibodies, whereas a high level of anti-vector neutralization was observed in mice who received homologous prime-boost regimens using the adenoviral vaccine.
Our data on the VRX1023 lentiviral vaccine in macaque monkeys in a prophylactic setting was presented at the Conference on Retroviral Opportunistic Infections (CROI) in San Francisco this February.