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
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.
Subject(s)
COVID-19 , Drug-Related Side Effects and Adverse Reactions , Respiratory Tract Diseases , Newcastle DiseaseABSTRACT
The dissemination of cases of the new SAR-COV-2 coronavirus represents a serious public health problem for Latin America and Peru. For this reason, it is important to characterize the genome of the isolates that circulate in Latin America. To characterize the complete genome of first samples of the virus circulating in Peru, we amplified seven overlapping segments of the viral genome by RT-PCR and sequenced using Miseq platform. The results indicate that the genomes of the Peruvian SARS-COV-2 samples belong to the genetic groups G and S. Likewise, a phylogenetic and MST analysis of the isolates confirm the introduction of multiple isolates from Europe and Asia that, after border closing, were transmitted locally in the capital and same regions of the country. These Peruvian samples (56%) grouped into two clusters inside G clade and share B.1.1.1 lineage. The characterization of these isolates must be considered for the use and design of diagnostic tools, and effective treatment and vaccine formulations.