Mucosal SARS-CoV-2 vaccination of rodents elicits superior systemic T central memory function and cross-neutralising antibodies against variants of concern.

BACKGROUND: COVID-19 vaccines used in humans are highly effective in limiting disease and death caused by the SARS-CoV-2 virus, yet improved vaccines that provide greater protection at mucosal surfaces, which could reduce break-through infections and subsequent transmission, are still needed. METHODS: Here we tested an intranasal (I.N.) vaccination with the receptor binding domain of Spike antigen of SARS-CoV-2 (S-RBD) in combination with the mucosal adjuvant mastoparan-7 compared with the sub-cutaneous (S.C.) route, adjuvanted by either M7 or the gold-standard adjuvant, alum, in mice, for immunological read-outs. The same formulation delivered I.N. or S.C. was tested in hamsters to assess efficacy. FINDINGS: I.N. vaccination improved systemic T cell responses compared to an equivalent dose of antigen delivered S.C. and T cell phenotypes induced by I.N. vaccine administration included enhanced polyfunctionality (combined IFN-γ and TNF expression) and greater numbers of T central memory (TCM) cells. These phenotypes were T cell-intrinsic and could be recalled in the lungs and/or brachial LNs upon antigen challenge after adoptive T cell transfer to naïve recipients. Furthermore, mucosal vaccination induced antibody responses that were similarly effective in neutralising the binding of the parental strain of S-RBD to its ACE2 receptor, but showed greater cross-neutralising capacity against multiple variants of concern (VOC), compared to S.C. vaccination. I.N. vaccination provided significant protection from lung pathology compared to unvaccinated animals upon challenge with homologous and heterologous SARS-CoV-2 strains in a hamster model. INTERPRETATION: These results highlight the role of nasal vaccine administration in imprinting an immune profile associated with long-term T cell retention and diversified neutralising antibody responses, which could be applied to improve vaccines for COVID-19 and other infectious diseases. FUNDING: This study was funded by Duke-NUS Medical School, the Singapore Ministry of Education, the National Medical Research Council of Singapore and a DBT-BIRAC Grant.

Drug targeting Nsp1-ribosomal complex shows antiviral activity against SARS-CoV-2.

The SARS-CoV-2 non-structural protein 1 (Nsp1) contains an N-terminal domain and C-terminal helices connected by a short linker region. The C-terminal helices of Nsp1 (Nsp1-C-ter) from SARS-CoV-2 bind in the mRNA entry channel of the 40S ribosomal subunit and blocks mRNA entry, thereby shutting down host protein synthesis. Nsp1 suppresses host immune function and is vital for viral replication. Hence, Nsp1 appears to be an attractive target for therapeutics. In this study, we have in silico screened Food and Drug Administration (FDA)-approved drugs against Nsp1-C-ter. Among the top hits obtained, montelukast sodium hydrate binds to Nsp1 with a binding affinity (KD) of 10.8 ± 0.2 µM in vitro. It forms a stable complex with Nsp1-C-ter in simulation runs with -95.8 ± 13.3 kJ/mol binding energy. Montelukast sodium hydrate also rescues the inhibitory effect of Nsp1 in host protein synthesis, as demonstrated by the expression of firefly luciferase reporter gene in cells. Importantly, it shows antiviral activity against SARS-CoV-2 with reduced viral replication in HEK cells expressing ACE2 and Vero-E6 cells. We, therefore, propose montelukast sodium hydrate can be used as a lead molecule to design potent inhibitors to help combat SARS-CoV-2 infection.

Indian scorpions collected in Karnataka: maintenance in captivity, venom extraction and toxicity studies.

BACKGROUND: Maintenance of scorpions under laboratory conditions is ideal for long-term venom collection to explore the therapeutic applications of scorpion venom. Collection of venom by electrical stimulation requires a reliable stimulator and effective restrainer. Thus, the present study was conducted to develop a convenient method to maintain scorpions and to extract their venom for toxicity studies via a modified restrainer and stimulator. METHODS: Four different scorpion species were collected, among which three species were maintained in the laboratory in containers that mimic their natural habitat. Venom was extracted from Hottentotta rugiscutis by electrical stimulation at 8 V for 18 months and LD50 was estimated by the graphic method of Miller and Tainter. RESULTS: A total of 373 scorpions including Hottentotta rugiscutis, Hottentotta tamulus, Lychas tricarinatus and Heterometrus swammerdami were collected, identified and maintained successfully, achieving a 97 % survival rate. Hottentotta rugiscutis yielded 6.0 mL of venom by electrical stimulation. The LD50 of H. rugiscutis venom was estimated to be 3.02 mg/kg of body weight in female Swiss albino mice. CONCLUSIONS: Scorpions were successfully maintained for 18 months. Herein we have also documented a simple, cost-effective method of venom extraction by electrical stimulation using a modified restrainer. Furthermore, Hottentotta rugiscutis was reported for the first time in Karnataka.

Indian scorpions collected in Karnataka: maintenance in captivity, venom extraction and toxicity studies

Background Maintenance of scorpions under laboratory conditions is ideal for long-term venom collection to explore the therapeutic applications of scorpion venom. Collection of venom by electrical stimulation requires a reliable stimulator and effective restrainer. Thus, the present study was conducted to develop a convenient method to maintain scorpions and to extract their venom for toxicity studies via a modified restrainer and stimulator. Methods Four different scorpion species were collected, among which three species were maintained in the laboratory in containers that mimic their natural habitat. Venom was extracted from Hottentotta rugiscutis by electrical stimulation at 8 V for 18 months and LD50 was estimated by the graphic method of Miller and Tainter. Results A total of 373 scorpions including Hottentotta rugiscutis, Hottentotta tamulus, Lychas tricarinatus and Heterometrus swammerdami were collected, identified and maintained successfully, achieving a 97 % survival rate. Hottentotta rugiscutis yielded 6.0 mL of venom by electrical stimulation. The LD50 of H. rugiscutis venom was estimated to be 3.02 mg/kg of body weight in female Swiss albino mice. Conclusions Scorpions were successfully maintained for 18 months. Herein we have also documented a simple, cost-effective method of venom extraction by electrical stimulation using a modified restrainer. Furthermore, Hottentotta rugiscutis was reported for the first time in Karnataka.

Indian scorpions collected in Karnataka: maintenance in captivity, venom extraction and toxicity studies

Background Maintenance of scorpions under laboratory conditions is ideal for long-term venom collection to explore the therapeutic applications of scorpion venom. Collection of venom by electrical stimulation requires a reliable stimulator and effective restrainer. Thus, the present study was conducted to develop a convenient method to maintain scorpions and to extract their venom for toxicity studies via a modified restrainer and stimulator. Methods Four different scorpion species were collected, among which three species were maintained in the laboratory in containers that mimic their natural habitat. Venom was extracted from Hottentotta rugiscutis by electrical stimulation at 8 V for 18 months and LD50 was estimated by the graphic method of Miller and Tainter. Results A total of 373 scorpions including Hottentotta rugiscutis, Hottentotta tamulus, Lychas tricarinatus and Heterometrus swammerdami were collected, identified and maintained successfully, achieving a 97 % survival rate. Hottentotta rugiscutis yielded 6.0 mL of venom by electrical stimulation. The LD50 of H. rugiscutis venom was estimated to be 3.02 mg/kg of body weight in female Swiss albino mice. Conclusions Scorpions were successfully maintained for 18 months. Herein we have also documented a simple, cost-effective method of venom extraction by electrical stimulation using a modified restrainer. Furthermore, Hottentotta rugiscutis was reported for the first time in Karnataka.(AU)