Ocular tropism of SARS-CoV-2 in animal models with retinal inflammation via neuronal invasion following intranasal inoculation.

Although ocular manifestations are reported in patients with COVID-19, consensus on ocular tropism of SARS-CoV-2 is lacking. Here, we infect K18-hACE2 transgenic mice with SARS-CoV-2 using various routes. We observe ocular manifestation and retinal inflammation with production of pro-inflammatory cytokines in the eyes of intranasally (IN)-infected mice. Intratracheal (IT) infection results in dissemination of the virus from the lungs to the brain and eyes via trigeminal and optic nerves. Ocular and neuronal invasions are confirmed using intracerebral (IC) infection. Notably, the eye-dropped (ED) virus does not cause lung infection and becomes undetectable with time. Ocular and neurotropic distribution of the virus in vivo is evident in fluorescence imaging with an infectious clone of SARS-CoV-2-mCherry. The ocular tropic and neuroinvasive characteristics of SARS-CoV-2 are confirmed in wild-type Syrian hamsters. Our data can improve the understanding regarding viral transmission and clinical characteristics of SARS-CoV-2 and help in improving COVID-19 control procedures.

Therapeutic strategy targeting host lipolysis limits infection by SARS-CoV-2 and influenza A virus.

The biosynthesis of host lipids and/or lipid droplets (LDs) has been studied extensively as a putative therapeutic target in diverse viral infections. However, directly targeting the LD lipolytic catabolism in virus-infected cells has not been widely investigated. Here, we show the linkage of the LD-associated lipase activation to the breakdown of LDs for the generation of free fatty acids (FFAs) at the late stage of diverse RNA viral infections, which represents a broad-spectrum antiviral target. Dysfunction of membrane transporter systems due to virus-induced cell injury results in intracellular malnutrition at the late stage of infection, thereby making the virus more dependent on the FFAs generated from LD storage for viral morphogenesis and as a source of energy. The replication of SARS-CoV-2 and influenza A virus (IAV), which is suppressed by the treatment with LD-associated lipases inhibitors, is rescued by supplementation with FFAs. The administration of lipase inhibitors, either individually or in a combination with virus-targeting drugs, protects mice from lethal IAV infection and mitigates severe lung lesions in SARS-CoV-2-infected hamsters. Moreover, the lipase inhibitors significantly reduce proinflammatory cytokine levels in the lungs of SARS-CoV-2- and IAV-challenged animals, a cause of a cytokine storm important for the critical infection or mortality of COVID-19 and IAV patients. In conclusion, the results reveal that lipase-mediated intracellular LD lipolysis is commonly exploited to facilitate RNA virus replication and furthermore suggest that pharmacological inhibitors of LD-associated lipases could be used to curb current COVID-19- and future pandemic outbreaks of potentially troublesome RNA virus infection in humans.