ABSTRACT
Since SARS-CoV-2 emerged in China, it has spread rapidly around the world. Effective vaccines and therapeutics for SARS-CoV-2−induced disease (coronavirus disease 2019; COVID19) are urgently needed. In order to assess the immune response to immunization with SARS-CoV-2 and the ability of the immune serum to neutralize the virus infection, we immunized a llama ( Lama glama) with the inactivated SARS-CoV-2 virus, and tested serum samples with an ELISA assay specific to the SARS-CoV-2, and viral neutralization by plaque-reduction neutralization test (PRNT). An increase in seroreactivity was observed for the immunized llama from week 4 onward, revealing seroconversion induced by the immunization, with the highest antibody titers on the 8 th boost. On the reactive serum sample, we performed Western Blot analysis that confirmed the positive ELISA findings, and antibodies from immune serum recognized various viral proteins. The gold standard PRNT showed a visible viral neutralization corresponding with ELISA results. Thus, our findings suggest this llama hyperimmune serum as a possible source of therapeutically antibodies against the SARS-CoV-2 virus infections to evaluate in further studies.
Subject(s)
COVID-19 , Severe Acute Respiratory SyndromeABSTRACT
Objective: The goal of this study is to determine the presence of SARS-CoV-2 in food surfaces and public space surfaces in 3 districts of Lima, Peru. Material and methods: Cross-sectional descriptive study, carried out in the districts of San Juan de Lurigancho, San Martin de Porres and Villa el Salvador. Surfaces that were exposed to the greatest user manipulation were selected, samples were swabbed for 4 weeks and transported to the laboratory to determine the presence of the virus. Results: 1095 inert surface samples and 960 food surface samples were evaluated for the identification of SARS-CoV-2 by the RT-PCR molecular test, whereby only one sample from an ATM (Automated Teller Machine) was positive. Conclusions: Most of the inert and food surfaces evaluated did not show the presence of SARS-CoV-2 during the time of sample collection. Despite the negative results, the frequency of disinfection measures should be maintained and increased, especially on inert high-contact surfaces, and hygiene measures on food should be continue.
ABSTRACT
The COVID-19 pandemic has claimed the lives of millions of people worldwide and threatens to become an endemic problem, therefore the need for as many types of vaccines as possible is of high importance. Because of the millions of doses required, it is desirable that vaccines are not only safe and effective, but also easy to administer, store, and inexpensive to produce. Newcastle Disease Virus (NDV) is responsible for a respiratory disease in chickens. It has no pathogenic homologue in humans. NDV is recognized as an oncolytic virus, and its use in humans for oncological treatment is being evaluated. In the present work, we have developed two types of NDV-vectored candidate vaccines, which carry the surface-exposed RBD and S1 antigens of SARS-CoV-2, respectively. These vaccine candidates were produced in specific-pathogen-free embryonating chicken eggs, and purified from allantoic fluid before lyophilization. These vaccines were administered intranasally to three different animal models: mice, rats and hamsters, and evaluated for safety, toxicity, immunogenicity, stability and efficacy. Efficacy was evaluated in a challenge assay against active SARS-CoV-2 virus in the Golden Syrian hamster model. The NDV-vectored vaccine based on the S1 antigen was shown to be safe and highly immunogenic, with the ability to neutralize SARS-CoV-2 in-vitro, even with an extreme dilution of 1/640. Our results reveal that this vaccine candidate protects the lungs of the animals, preventing cellular damage in this tissue. In addition, this vaccine reduces the viral load in the lungs, suggesting that it may significantly reduce the likelihood of transmission. Being lyophilized, this vaccine candidate is very stable and can be stored for several months at 4-8{degrees}C. In conclusion, our NDV-based vaccine candidate has shown a very favorable performance in the pre-clinical study, serving as evidence for a future evaluation in a Phase-I human clinical trial. This candidate represents a promising tool in the fight against COVID-19.