Safety and immunogenicity of different 17DD yellow fever vaccines in golden-headed tamarins (Leontopithecus chrysomelas): Inhibition of viremia and RNAemia after homologous live-attenuated vaccination

Yellow fever (YF) is a viral disease that affects both humans and non-human primates (NHPs). Neotropical monkeys are more severely stricken by YF and the impact of the disease can be devastating to the endangered golden-headed lion tamarins (GHLTs, Leontopithecus chrysomelas). Susceptible GHLTs were immunized with the commercial Brazilian YF 17DD live attenuated vaccine or two other experimental non-replicating YF vaccines: a purified whole-virus, b-propiolactone-inactivated vaccine and a plant-derived recombinant subunit vaccine. Safety, immunogenicity and viremia and RNAemia blockade were characterized. No YF clinical manifestations were observed in any of the GHLTs that received the attenuated virus, either as a vaccine or as the homologous vaccination with the live attenuated vaccine used as the challenge virus. All three concentrations of the attenuated vaccine induced neutralizing antibodies and only one in 16 animals had detectable viremia and RNAemia after challenge. The inactivated vaccine elicited neutralizing antibodies preventing post-challenge viremia and RNAemia in five out of six animals. The plant-based vaccine induced neutralizing antibodies in five out of six animals and prevented viremia and RNAemia in three out of six against challenge. The safety profile and the immunogenicity of the YF attenuated vaccine were demonstrated in GHLTs with a blocking effectiveness over 90 %, where blockade can be defined as the capacity to prevent viremia and RNAemia after homologous vaccination with the live attenuated vaccine. The use of the inactivated vaccine in this species served as a preliminary pre-clinical study for this approach and after administration in three-dose regimen demonstrated a blocking profile of 83 %. Using a two-dose regimen, the plant-based vaccine was able to block viremia and RNAemia in 50 % of the animals. The present study can endorse the use of attenuated or non-replicating yellow fever vaccines in New World primates threatened by the recent disease outbreaks in Brazil.