HIV vaccines in Kids: Unexpected findings
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 in PedVacc001 trial.
This begs the question of how vaccines against HIV-1 will interact with other concurrent vaccinations provided to individuals. It must be mentioned that Modified Virus Ankara is an attenuated lab strain developed by Anton Mayr and is derived from the Chorioallantois Vaccine Ankara (CVA) strain of the vaccine virus but was renamed MVA after the 516th passage of CVA on primary chicken embryo fibroblasts. The MVA is 178 kb in length and lost about 15% of the genome compared to CVA, does not encode any known pox viral immune evasion and virulence factors and is avirulent. MVA has a double-stranded DNA and the virus replicates in the cytoplasm, with very low possibility of integration into the host chromosome.
In all, it seems that the immune response to MVA-HIV-A and HBV show some interaction dynamics that need to be investigated.
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 in PedVacc001 trial.
This begs the question of how vaccines against HIV-1 will interact with other concurrent vaccinations provided to individuals. It must be mentioned that Modified Virus Ankara is an attenuated lab strain developed by Anton Mayr and is derived from the Chorioallantois Vaccine Ankara (CVA) strain of the vaccine virus but was renamed MVA after the 516th passage of CVA on primary chicken embryo fibroblasts. The MVA is 178 kb in length and lost about 15% of the genome compared to CVA, does not encode any known pox viral immune evasion and virulence factors and is avirulent. MVA has a double-stranded DNA and the virus replicates in the cytoplasm, with very low possibility of integration into the host chromosome.
In all, it seems that the immune response to MVA-HIV-A and HBV show some interaction dynamics that need to be investigated.
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