Coronaviruses exploit a host cysteine-aspartic protease for replication.

Highly pathogenic coronaviruses, including severe acute respiratory syndrome coronavirus 2 (refs. 1,2) (SARS-CoV-2), Middle East respiratory syndrome coronavirus3 (MERS-CoV) and SARS-CoV-1 (ref. 4), vary in their transmissibility and pathogenicity. However, infection by all three viruses results in substantial apoptosis in cell culture5-7 and in patient tissues8-10, suggesting a potential link between apoptosis and pathogenesis of coronaviruses. Here we show that caspase-6, a cysteine-aspartic protease of the apoptosis cascade, serves as an important host factor for efficient coronavirus replication. We demonstrate that caspase-6 cleaves coronavirus nucleocapsid proteins, generating fragments that serve as interferon antagonists, thus facilitating virus replication. Inhibition of caspase-6 substantially attenuates lung pathology and body weight loss in golden Syrian hamsters infected with SARS-CoV-2 and improves the survival of mice expressing human DPP4 that are infected with mouse-adapted MERS-CoV. Our study reveals how coronaviruses exploit a component of the host apoptosis cascade to facilitate virus replication.

COVID-19-related cognitive dysfunction may be associated with transient disruption in the DLPFC glutamatergic pathway.

Cognitive impairment has recently attracted researchers as one of the possible neuropsychiatric manifestations of COVID-19, although how the infection perpetuates impairment of cognitive functions is still obscure. We presented a 29-year-old male patient with COVID-19 who developed new-onset transient attention deficit and memory problems following a SARS-CoV-2 infection. Structural neuroimaging was normal. MR-spectroscopy (MRS) of the bilateral DLPFC revealed significant for decreased levels of N-acetylaspartate (NAA), glutamate, and glutamate/glutamine ratio. After a follow-up without any medical treatment but with suggestions of memory exercises for three months a control MRS screening of DLPFC showed improved levels of NAA, glutamate, and glutamate/glutamine ratio. This report may suggest that cognitive deficits in SARS-CoV-2 infection can result from glutamatergic dysfunction with decreased NAA and glutamate levels in bilateral DLPFC.

Impact of I/D polymorphism of angiotensin-converting enzyme 1 (ACE1) gene on the severity of COVID-19 patients.

Severe acute respiratory syndrome corona virus-2 (SARS-CoV-2) has first emerged from China in December 2019 and causes coronavirus induced disease 19 (COVID-19). Since then researchers worldwide have been struggling to detect the possible pathogenesis of this disease. COVID-19 showed a wide range of clinical behavior from asymptomatic to severe acute respiratory disease syndrome. However, the etiology of susceptibility to severe lung injury is not yet fully understood. Angiotensin-converting enzyme1 (ACE1) convert angiotensin I into Angiotensin II that was further metabolized by ACE 2 (ACE2). The binding ACE2 receptor to SARS-CoV-2 facilitate its enter into the host cell. The interaction and imbalance between ACE1 and ACE2 play a crucial role in the pathogenesis of lung injury. Thus, the aim of this study was to investigate the association of ACE1 I/D polymorphism with severity of Covid-19. The study included RT-PCR confirmed 269 cases of Covid-19. All cases were genotyped for ACE1 I/D polymorphism using polymerase chain reaction and followed by statistical analysis (SPSS, version 15.0). We found that ACE1 DD genotype, frequency of D allele, older age (≥46 years), unmarried status, and presence of diabetes and hypertension were significantly higher in severe COVID-19 patient. ACE1 ID genotype was significantly independently associated with high socio-economic COVID-19 patients (OR: 2.48, 95% CI: 1.331-4.609). These data suggest that the ACE1 genotype may impact the incidence and clinical outcome of COVID-19 and serve as a predictive marker for COVID-19 risk and severity.