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Front Immunol ; 13: 845969, 2022.
Article in English | MEDLINE | ID: covidwho-1775680


To control the coronavirus disease 2019 (COVID-19) pandemic and the emergence of different variants of concern (VoCs), novel vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are needed. In this study, we report the potent immunogenicity and efficacy induced in hamsters by a vaccine candidate based on a modified vaccinia virus Ankara (MVA) vector expressing a human codon optimized full-length SARS-CoV-2 spike (S) protein (MVA-S). Immunization with one or two doses of MVA-S elicited high titers of S- and receptor-binding domain (RBD)-binding IgG antibodies and neutralizing antibodies against parental SARS-CoV-2 and VoC alpha, beta, gamma, delta, and omicron. After SARS-CoV-2 challenge, MVA-S-vaccinated hamsters showed a significantly strong reduction of viral RNA and infectious virus in the lungs compared to the MVA-WT control group. Moreover, a marked reduction in lung histopathology was also observed in MVA-S-vaccinated hamsters. These results favor the use of MVA-S as a potential vaccine candidate for SARS-CoV-2 in clinical trials.

COVID-19 , Animals , Antibodies, Viral , COVID-19/prevention & control , COVID-19 Vaccines , Cricetinae , Humans , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/genetics , Vaccinia virus/genetics
Preprint in English | EuropePMC | ID: ppcovidwho-328811


The protective efficacy of vaccines against SARS-CoV-2 infection in the brain is yet unclear. Here, in the susceptible transgenic K18-hACE2 mouse model of severe COVID-19 disease, we report a detailed spatiotemporal description of the SARS-CoV-2 infection and replication in different areas of the brain. Remarkably, SARS-CoV-2 brain replication occurs primarily in neurons, producing important neuropathological alterations such as neuronal loss, incipient signs of neuroinflammation, and vascular damage in SARS-CoV-2 infected mice. Notably, one or two doses of a modified vaccinia virus Ankara (MVA) vector expressing the SARS-CoV-2 spike (S) protein (MVA-CoV2-S) conferred full protection against SARS-CoV-2 cerebral infection, preventing virus replication in all areas of the brain and its associated damage. This protection was maintained even after SARS-CoV-2 reinfection. To our knowledge, this is the first study of a COVID-19 vaccine candidate showing 100% efficacy against SARS-CoV-2 brain infection and damage, reinforcing the use of MVA-CoV2-S as a promising vaccine candidate against SARS-CoV-2/COVID-19, worth to move forward into clinical trials.

Front Immunol ; 12: 824728, 2021.
Article in English | MEDLINE | ID: covidwho-1686477


We generated an optimized COVID-19 vaccine candidate based on the modified vaccinia virus Ankara (MVA) vector expressing a full-length prefusion-stabilized SARS-CoV-2 spike (S) protein, termed MVA-CoV2-S(3P). The S(3P) protein was expressed at higher levels (2-fold) than the non-stabilized S in cells infected with the corresponding recombinant MVA viruses. One single dose of MVA-CoV2-S(3P) induced higher IgG and neutralizing antibody titers against parental SARS-CoV-2 and variants of concern than MVA-CoV2-S in wild-type C57BL/6 and in transgenic K18-hACE2 mice. In immunized C57BL/6 mice, two doses of MVA-CoV2-S or MVA-CoV2-S(3P) induced similar levels of SARS-CoV-2-specific B- and T-cell immune responses. Remarkably, a single administration of MVA-CoV2-S(3P) protected all K18-hACE2 mice from morbidity and mortality caused by SARS-CoV-2 infection, reducing SARS-CoV-2 viral loads, histopathological lesions, and levels of pro-inflammatory cytokines in the lungs. These results demonstrated that expression of a novel full-length prefusion-stabilized SARS-CoV-2 S protein by the MVA poxvirus vector enhanced immunogenicity and efficacy against SARS-CoV-2 in animal models, further supporting MVA-CoV2-S(3P) as an optimized vaccine candidate for clinical trials.

COVID-19 Vaccines/immunology , COVID-19/prevention & control , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Vaccines, DNA/immunology , Viral Vaccines/immunology , Aged , Angiotensin-Converting Enzyme 2/genetics , Angiotensin-Converting Enzyme 2/metabolism , Animals , Antibodies, Neutralizing/blood , Antibodies, Viral/blood , COVID-19/mortality , COVID-19 Vaccines/genetics , Cell Line, Tumor , Chick Embryo , Chlorocebus aethiops , Cytokines/analysis , Female , HeLa Cells , Humans , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Plasmids/genetics , Spike Glycoprotein, Coronavirus/genetics , Vaccines, DNA/genetics , Vaccinia virus/immunology , Vero Cells , Viral Vaccines/genetics