ABSTRACT
BACKGROUND: Vaccines that are shelf stable and easy to administer are crucial to improve vaccine access and reduce severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission around the world. METHODS: In this study, we demonstrate that an oral, adenovirus-based vaccine candidate protects against SARS-CoV-2 in a Syrian hamster challenge model. RESULTS: Hamsters administered 2 doses of VXA-CoV2-1 showed a reduction in weight loss and lung pathology and had completely eliminated infectious virus 5 days postchallenge. Oral immunization induced antispike immunoglobulin G, and neutralizing antibodies were induced upon oral immunization with the sera, demonstrating neutralizing activity. CONCLUSIONS: Overall, these data demonstrate the ability of oral vaccine candidate VXA-CoV2-1 to provide protection against SARS-CoV-2 disease.
Subject(s)
Adenovirus Vaccines/administration & dosage , COVID-19 Vaccines/administration & dosage , COVID-19/prevention & control , Mesocricetus , Adenovirus Vaccines/immunology , Animals , Antibodies, Neutralizing , Antibodies, Viral , COVID-19/virology , COVID-19 Vaccines/immunology , Cricetinae , SARS-CoV-2 , Spike Glycoprotein, Coronavirus , VaccinationABSTRACT
The development of a safe and effective vaccine against SARS-CoV-2, the causative agent of pandemic coronavirus disease-2019 (COVID-19), is a global priority. Here, we aim to develop novel SARS-CoV-2 vaccines based on a derivative of less commonly used rare adenovirus serotype AdC68 vector. Three vaccine candidates were constructed expressing either the full-length spike (AdC68-19S) or receptor-binding domain (RBD) with two different signal sequences (AdC68-19RBD and AdC68-19RBDs). Single-dose intramuscular immunization induced robust and sustained binding and neutralizing antibody responses in BALB/c mice up to 40 weeks after immunization, with AdC68-19S being superior to AdC68-19RBD and AdC68-19RBDs. Importantly, immunization with AdC68-19S induced protective immunity against high-dose challenge with live SARS-CoV-2 in a golden Syrian hamster model of SARS-CoV-2 infection. Vaccinated animals demonstrated dramatic decreases in viral RNA copies and infectious virus in the lungs, as well as reduced lung pathology compared to the control animals. Similar protective effects were also found in rhesus macaques. Taken together, these results confirm that AdC68-19S can induce protective immune responses in experimental animals, meriting further development toward a human vaccine against SARS-CoV-2.
Subject(s)
Adenovirus Vaccines/administration & dosage , COVID-19 Vaccines/administration & dosage , COVID-19/prevention & control , Immunization Schedule , Immunogenicity, Vaccine , SARS-CoV-2/immunology , Vaccination/methods , Adenovirus Vaccines/immunology , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/virology , COVID-19 Vaccines/immunology , Cricetinae , Disease Models, Animal , Female , HEK293 Cells , Humans , Male , Mice , Mice, Inbred BALB C , Pan troglodytes , RNA, Viral/blood , Spike Glycoprotein, Coronavirus/immunology , Transfection , Treatment OutcomeSubject(s)
Adenovirus Vaccines/administration & dosage , COVID-19 Vaccines/administration & dosage , COVID-19/epidemiology , Population Surveillance , Sinus Thrombosis, Intracranial/epidemiology , Vaccination/trends , Adenovirus Vaccines/adverse effects , COVID-19/complications , COVID-19/prevention & control , COVID-19 Vaccines/adverse effects , Hospitalization/trends , Humans , Sinus Thrombosis, Intracranial/chemically induced , United States/epidemiology , Vaccination/adverse effectsABSTRACT
COVID-19 vaccines emerging from different platforms differ in efficacy, duration of protection, and side effects. To maximize the benefits of vaccination, we explored the utility of employing a heterologous prime-boost strategy in which different combinations of the four types of leading COVID-19 vaccine candidates that are undergoing clinical trials in China were tested in a mouse model. Our results showed that sequential immunization with adenovirus vectored vaccine followed by inactivated/recombinant subunit/mRNA vaccine administration specifically increased levels of neutralizing antibodies and promoted the modulation of antibody responses to predominantly neutralizing antibodies. Moreover, a heterologous prime-boost regimen with an adenovirus vector vaccine also improved Th1-biased T cell responses. Our results provide new ideas for the development and application of COVID-19 vaccines to control the SARS-CoV-2 pandemic.