Immunization with SARS-CoV-2 Nucleocapsid protein triggers a pulmonary immune response in rats

Abstract

The SARS-CoV-2 pandemic have been affecting millions of people worldwide, since the beginning of 2020. COVID-19 can cause a wide range of clinical symptoms, which varies from asymptomatic presentation to severe respiratory insufficiency, exacerbation of immune response, disseminated microthrombosis and multiple organ failure, which may lead to dead. Due to the rapid spread of SARS-CoV-2, the development of vaccines to minimize COVID-19 severity in the world population is imperious. One of the employed techniques to produce vaccines against emerging viruses is the synthesis of recombinant proteins, which can be used as immunizing agents. Based on the exposed, the aim of the present study was to verify the systemic and immunological effects of IM administration of recombinant Nucleocapsid protein (NP), derived from SARS-CoV-2 and produced by this research group, in 2 different strains of rats (Rattus norvegicus); Wistar and Lewis. For this purpose, experimental animals received 4 injections of NP, once a week, and were submitted to biochemical and histological analysis. Our results showed that NP inoculations were safe for the animals, which presented no clinical symptoms of worrying side effects, nor laboratorial alterations in the main biochemical and histological parameters, suggesting the absence of toxicity induced by NP. Moreover, NP injections successfully triggered the production of specific anti-SARS-CoV-2 IgG antibodies by both Wistar and Lewis rats, showing the sensitization to have been well sufficient for the immunization of these strains of rats. Additionally, we observed the local lung activation of the Bronchus-Associated Lymphoid Tissue (BALT) of rats in the NP groups, suggesting that NP elicits specific lung immune response. Although pre-clinical and clinical studies are still required, our data support the recombinant NP produced by this research group as a potential immunizing agent for massive vaccination, and may represent advantages upon other recombinant proteins, since it seems to induce specific pulmonary protection.

SARS-CoV-2 infection-induced immunity reduces rates of reinfection and hospitalization caused by the Delta or Omicron variants

“…Here, we have updated the data with additional samples from Turkey, and responses towards the N were trending upward compared to responses against the S protein of SARS-CoV-2. In addition, the findings from mice in our study support the potential for protection of pre-existing cross-immune responses against N and S. Lastly, immunization of rats with N was shown to trigger a pulmonary immune response through lymphocyte and macrophage infiltration, which may prove advantageous towards protection [ 22 ]. These findings support the inclusion of other antigens, such as N, in future vaccine designs toward creating broader immunity.…”

The HLA-II immunopeptidome of SARS-CoV-2

“…In the context of vaccine design, it is important to decipher both CD4 + and CD8 + T cell epitopes because effective vaccines require potent induction of both arms of the adaptive cellular response. Many of the current vaccine strategies rely on the delivery of a single viral protein to induce both CD8 + and CD4 + T cell responses and mainly focus on the structural proteins S or N. 8 , 64 – 69 However, HLA-I and HLA-II presentation, which facilitate CD8 + and CD4 + T cell responses, respectively, have distinct antigen-processing steps, raising the likelihood that each of these pathways samples a different subset of viral proteins.…”

Next-Generation Vaccines against COVID-19 Variants: Beyond the Spike Protein

“…N protein-based subunit vaccines have also been developed and tested. SARS-CoV-2 N protein either alone or in combination with well-known adjuvants (e.g., Freund's adjuvant, alum, or QS-21) has been shown to be immunogenic in animal models [82,83]. A synthetic peptide vaccine comprising N epitopes (HLA class I bound cytotoxic T lymphocyte peptide) along with adjuvants (Tolllike receptor [TLR] 4 agonist (MPLA) and TLR9 agonist [CpG oligonucleotide]) have shown moderate protection against SRAS-CoV-2 in Rhesus macaques [84].…”