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1.
Mol Ther Methods Clin Dev ; 25: 215-224, 2022 Jun 09.
Article in English | MEDLINE | ID: covidwho-1740074

ABSTRACT

New platforms are needed for the design of novel prophylactic vaccines and advanced immune therapies. Live-attenuated yellow fever vaccine YF17D serves as a vector for several licensed vaccines and platform for novel candidates. On the basis of YF17D, we developed an exceptionally potent COVID-19 vaccine candidate called YF-S0. However, use of such live RNA viruses raises safety concerns, such as adverse events linked to original YF17D (yellow fever vaccine-associated neurotropic disease [YEL-AND] and yellow fever vaccine-associated viscerotropic disease [YEL-AVD]). In this study, we investigated the biodistribution and shedding of YF-S0 in hamsters. Likewise, we introduced hamsters deficient in signal transducer and activator of transcription 2 (STAT2) signaling as a new preclinical model of YEL-AND/AVD. Compared with YF17D, YF-S0 showed improved safety with limited dissemination to brain and visceral tissues, absent or low viremia, and no shedding of infectious virus. Considering that yellow fever virus is transmitted by Aedes mosquitoes, any inadvertent exposure to the live recombinant vector via mosquito bites is to be excluded. The transmission risk of YF-S0 was hence compared with readily transmitting YF-Asibi strain and non-transmitting YF17D vaccine, with no evidence for productive infection of mosquitoes. The overall favorable safety profile of YF-S0 is expected to translate to other vaccines based on the same YF17D platform.

2.
EuropePMC;
Preprint in English | EuropePMC | ID: ppcovidwho-327091

ABSTRACT

New platforms are urgently needed for the design of novel prophylactic vaccines and advanced immune therapies. Live-attenuated yellow fever vaccine YF17D serves as vector for several licensed vaccines and platform for novel vaccine candidates. Based on YF17D, we developed YF-S0 as exceptionally potent COVID-19 vaccine candidate. However, use of such live RNA virus vaccines raises safety concerns, i.e., adverse events linked to original YF17D (yellow fever vaccine-associated neurotropic;YEL-AND, and viscerotropic disease;YEL-AVD). In this study, we investigated the biodistribution and shedding of YF-S0 in hamsters. Likewise, we introduced hamsters deficient in STAT2 signaling as new preclinical model of YEL-AND/AVD. Compared to parental YF17D, YF-S0 showed an improved safety with limited dissemination to brain and visceral tissues, absent or low viremia, and no shedding of infectious virus. Considering yellow fever virus is transmitted by Aedes mosquitoes, any inadvertent exposure to the live recombinant vector via mosquito bites is to be excluded. The transmission risk of YF-S0 was hence evaluated in comparison to readily transmitting YFV-Asibi strain and non-transmitting YF17D vaccine, with no evidence for productive infection of vector mosquitoes. The overall favorable safety profile of YF-S0 is expected to translate to other novel vaccines that are based on the same YF17D platform.

3.
Nature ; 590(7845): 320-325, 2021 02.
Article in English | MEDLINE | ID: covidwho-953381

ABSTRACT

The expanding pandemic of coronavirus disease 2019 (COVID-19) requires the development of safe, efficacious and fast-acting vaccines. Several vaccine platforms are being leveraged for a rapid emergency response1. Here we describe the development of a candidate vaccine (YF-S0) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that uses live-attenuated yellow fever 17D (YF17D) vaccine as a vector to express a noncleavable prefusion form of the SARS-CoV-2 spike antigen. We assess vaccine safety, immunogenicity and efficacy in several animal models. YF-S0 has an excellent safety profile and induces high levels of SARS-CoV-2 neutralizing antibodies in hamsters (Mesocricetus auratus), mice (Mus musculus) and cynomolgus macaques (Macaca fascicularis), and-concomitantly-protective immunity against yellow fever virus. Humoral immunity is complemented by a cellular immune response with favourable T helper 1 polarization, as profiled in mice. In a hamster model2 and in macaques, YF-S0 prevents infection with SARS-CoV-2. Moreover, a single dose conferred protection from lung disease in most of the vaccinated hamsters within as little as 10 days. Taken together, the quality of the immune responses triggered and the rapid kinetics by which protective immunity can be attained after a single dose warrant further development of this potent SARS-CoV-2 vaccine candidate.


Subject(s)
COVID-19 Vaccines/immunology , COVID-19/immunology , COVID-19/prevention & control , Genetic Vectors/genetics , SARS-CoV-2/immunology , Vaccines, Attenuated/immunology , Yellow Fever Vaccine/genetics , Animals , COVID-19 Vaccines/administration & dosage , COVID-19 Vaccines/adverse effects , COVID-19 Vaccines/genetics , Cricetinae , Disease Models, Animal , Female , Glycosylation , Macaca fascicularis/genetics , Macaca fascicularis/immunology , Macaca fascicularis/virology , Male , Mesocricetus/genetics , Mesocricetus/immunology , Mesocricetus/virology , Mice , Safety , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism , Vaccines, Attenuated/administration & dosage , Vaccines, Attenuated/adverse effects , Vaccines, Attenuated/genetics
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