Safety, immunogenicity and efficacy of Relcovax®, a dual receptor binding domain (RBD) and nucleocapsid (N) subunit protein vaccine candidate against SARS-CoV-2 virus.

SARS-CoV-2, severe acute respiratory syndrome coronavirus-2, causes coronavirus disease- 2019 (COVID-19). Mostly, COVID-19 causes respiratory symptoms that can resemble those of a cold, the flu, or pneumonia. COVID-19 may harm more than just lungs and respiratory systems. It may also have an impact on other parts of the body and debilitating effects on humans, necessitating the development of vaccines at an unprecedented rate in order to protect humans from infections. In response to SARS-CoV-2 infection, mRNA, viral vector-based carrier and inactivated virus-based vaccines, as well as subunit vaccines, have recently been developed. We developed Relcovax®, a dual antigen (Receptor binding domain (RBD) and Nucleocapsid (N) proteins) subunit protein vaccine candidate. Preliminary mouse preclinical studies revealed that Relcovax® stimulates cell-mediated immunity and provides broader protection against two SARS-CoV-2 variants, including the delta strain. Before conducting human studies, detailed preclinical safety assessments are required, so Relcovax® was tested for safety, and immunogenicity in 28-day repeated dose toxicity studies in rats and rabbits. In the toxicity studies, there were no mortality or morbidity, abnormal clinical signs, abnormalities in a battery of neurobehavioral observations, abnormalities in detailed clinical and ophthalmological examinations, or changes in body weights or feed consumption. In any of the studies, no abnormal changes in organ weights, haematology, clinical chemistry, urinalysis parameters, or pathological findings were observed. Immunogenicity tests on rats and rabbits revealed 100 % seroconversion. Relcovax® was therefore found to be safe in animals, with a No Observed Adverse Effect Level (NOAEL) of 20 µg/protein in rats and rabbits. In efficacy studies, Relcovax® immunised hamsters demonstrated dose-dependent protection against SARS-CoV-2 infection, with a high dose (20 µg/protein) being the most protective, while in cynomolgus macaque monkey study, lowest dose 5 µg/protein had the highest efficacy. In conclusion, Relcovax® was found to be safe, immunogenic, and efficacious in in vivo studies.

The effects of perfluorooctanoic acid (PFOA) on fetal and adult rat testis.

Perfluorooctanoic acid (PFOA) is a widely dispersed synthetic chemical, which accumulates in living organisms and has been connected with male reproductive disorders. To monitor the effects of PFOA, fetal rat testes or seminiferous tubule segments (stage VII-VIII) of adult rats were cultured in 0-100 µg/ml PFOA for 24 h. Afterwards, cAMP, progesterone, testosterone and StAR protein levels were measured from the fetal testes culture. Measurements were combined with immunohistochemistry, immunofluorescence, TUNEL and flow cytometric analysis to monitor cell death in somatic and germ cells. This study shows that the levels of cAMP, progesterone, testosterone and expression of StAR decreased significantly in PFOA 50 and 100 µg/ml. PFOA affected cell populations significantly by decreasing the amount of diploid, proliferating, meiotic I and G2/M-phase cells in adult rat testis. However, PFOA did not affect fetal, proliferating or adult rat Sertoli cells but an increased tendency of apoptosis in fetal Leydig cells was observed.

Sympathetic neuron-associated macrophages contribute to obesity by importing and metabolizing norepinephrine.

The cellular mechanism(s) linking macrophages to norepinephrine (NE)-mediated regulation of thermogenesis have been a topic of debate. Here we identify sympathetic neuron-associated macrophages (SAMs) as a population of cells that mediate clearance of NE via expression of solute carrier family 6 member 2 (SLC6A2), an NE transporter, and monoamine oxidase A (MAOA), a degradation enzyme. Optogenetic activation of the sympathetic nervous system (SNS) upregulates NE uptake by SAMs and shifts the SAM profile to a more proinflammatory state. NE uptake by SAMs is prevented by genetic deletion of Slc6a2 or inhibition of the encoded transporter. We also observed an increased proportion of SAMs in the SNS of two mouse models of obesity. Genetic ablation of Slc6a2 in SAMs increases brown adipose tissue (BAT) content, causes browning of white fat, increases thermogenesis, and leads to substantial and sustained weight loss in obese mice. We further show that this pathway is conserved, as human sympathetic ganglia also contain SAMs expressing the analogous molecular machinery for NE clearance, which thus constitutes a potential target for obesity treatment.