Vaccine Guru

A recent paper by Li et al., from the lab of Dan Barouch at Harvard shows very interesting results based on observations made from Rhesus macaques injected with experimental HIV vaccines.  One of the key questions facing HIV vaccine researchers is whether one should design vaccine that stands a fair chance at inducing an immune response in the genital mucosa, since this is the portal of entry for the virus. The mucosal immune response is a key factor in vaccine efficacy and success against infection or disease progression. This paper that appeared in Journal of Virology (doi: 10.1128/JVI.02095-14) first determined that the amount of IgG in serum was significantly higher than IgA whereas the amount of IgA in colorectal mucosal secretions was significantly higher than IgG. They also confirmed that IgA from mucosal secretions was largely secretory IgA and not serum contamination. Next, they injected rhesus macaques with candidate HIV vaccines. 16 animals were injected (i.m.) with Ad

PedVacc 002: Njuguna et al., Vaccine (2014). After a clinical trial evaluating safety of a modified vaccinia virus Ankara (MVA) expressing HIV in infants born to HIV-1 negative mothers in Gambia (PedVacc001 trial), a research group working out of Nairobi tested the vaccine in another clinical trial (PedVacc002) in Kenya to test the safety of the vaccine, which was the primary outcome. The latter trial however was carried out in infants born to HIV-1-positive mothers. The vaccine was well tolerated with very rare adverse events that were similar between vaccine and no-treatment arms. The MVA-HIVA was safe but no sufficiently immunogenic in infants. The immune response of the infants to all routine childhood vaccines was also tested and interestingly, while 92% of the control subjects were found to have protective antibodies against Hepatitis B virus, only 71% of the vaccinees showed a similar effect and this was statistically significant (p=0.05). This difference was not observed