Yellow fever (YF) is a high-lethality viral disease, endemic in tropical regions of South America and Africa,with a population of over 900 million people under risk. A highly effective attenuated vaccine, producedin embryonated eggs, has been used for about 80 years. However, egg-based production limits manufac-turing capacity, and vaccine shortage led to the emergency use of a fractional dose (1/5) by the WHO in anoutbreak in Africa in 2016 and by Brazilian authorities during an outbreak in 2018. In addition, rare butfatal adverse events of this vaccine have been reported since 2001. These two aspects make clear the needfor the development of a new vaccine. In an effort to develop an inactivated YF vaccine, Bio-Manguinhos/FIOCRUZ started developing a new vaccine based on the production of the attenuated 17DD virus inserum-free conditions in Vero cells propagated in bioreactors, followed by chromatography-based purifi-cation andb-propiolactone inactivation.Virus purification was studied in this work. Capture was performed using an anion-exchange mem-brane adsorber (SartobindÒQ), resulting in a virus recovery of 80.2 ± 4.8% and a residual DNA level of1.3 ± 1.6 ng/dose, thus in accordance with the recommendations of the WHO (<10 ng/dose). However,the level of host cell proteins (HCP) was still high for a human vaccine, so a second chromatography stepwas developed based on a multimodal resin (CaptoTMCore 700). This step resulted in a virus recovery of65.7 ± 4.8% and decreased HCP levels to 345 ± 25 ppm. The overall virus recovery in these chromatogra-phy steps was 52.7%. SDS-PAGE of the purified sample showed a band with molecular mass of 56 kDa,thus consistent with the virus envelope protein (E) and corresponding to 96.7% of identified proteins.A Western blot stained with an antibody against the E protein showed a single band, confirming the iden-tity of the sample.Ó2019 Elsevier Ltd. All rights reserved.1. IntroductionYellow fever (YF) is a non-contagious viral hemorrhagic disease,transmitted by infected mosquitoes, in particularAedes aegypti(urban cycle) andHaemagogussp. (jungle cycle). The disease canoccur in mild or severe forms, the latter being characterized byfever, nausea, vomiting, epigastric pain, hepatitis with jaundice,renal failure, hemorrhage and shock. There is no specific antiviraltreatment. According to the CDC, currently there are 34 countriesin Africa and 13 in South America where there is risk of transmis-sion of yellow fever virus (YFV)[1]. The vast majority of YF casesoccur in Africa, and estimates by Garske et al.[2]indicate thatthe yellow fever burden in Africa in 2013 was 130,000 cases withfever and jaundice or haemorrhage, including 78,000 deaths. Thisis comparable to the worldwide annual average number of hospi-talizations and deaths caused by influenza. Non-human primatesare reservoir hosts of the virus, making it impossible to eradicatethe mosquito-borne jungle transmission, which primarily affectsyoung male forestry and agricultural workers. Over the last20 years, an increase in the number of YF cases worldwide hasbeen observed, and possible causes could be declining populationimmunity to infection, deforestation, urbanization, populationmovements and climate change[3].https://doi.org/10.1016/j.vaccine.2019.04.0770264-410X/Ó2019 Elsevier Ltd. All rights reserved.⇑Corresponding author at: Oswaldo Cruz Foundation (FIOCRUZ), Bio-Manguin-hos, Avenida Brasil 4365, 21045-900 Rio de Janeiro/RJ, Brazil.E-mail address:tania@bio.fiocruz.br(T.P. Pato).Vaccine 37 (2019) 3214–3220Contents lists available atScienceDirectVaccinejournal homepage: www.elsevier.com/locate/vaccine.