Seroprevalence of immunoglobulin M and G antibodies against SARS-CoV-2 in ophthalmic patients (preprint)

Using serological test to estimate the prevalence and infection potential of coronavirus disease 2019 in ocular diseases patients help understand the relationship between ocular diseases and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We conducted a cross-sectional study assaying the IgG and IgM antibodies in 1331 individuals with ocular diseases by using a magnetic chemiluminescence enzyme immunoassay kit, during the period from February 2020 to May 2020. In our study, the seroposivity in total ocular disease patients was 0.83% (11/1331). The patients with different ocular diseases including xerophthalmia, keratitis, conjunctival cyst, cataract, glaucoma, refractive error, strabismus and others had seroposivity of 2.94%, 12.5%, 25%, 4.41%, 2.63%, 1.6%, 2.22% and 0%, respectively. Among that, two ocular surface disease groups (keratitis and conjunctival cyst) had higher seroprevalence compared with others. All the participants were reverse transcription polymerase chain reaction negative for SARS-CoV-2 from throat swabs. Our study evaluated the seroprevalence in patients with different ocular diseases, which will help us understand the relationship between ocular disease and SARS-CoV-2 infection. Furthermore, the serological test for the presence of IgM and/or IgG antibodies against SARS-CoV-2 might provide accurate estimate of the prevalence of SARS-CoV-2 infection in patients with ocular diseases.

Single-cell screening of SARS-CoV-2 target cells in pets, livestock, poultry and wildlife (preprint)

A few animals have been suspected to be intermediate hosts of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, a large-scale single-cell screening of SARS-CoV-2 target cells on a wide variety of animals is missing. Here, we constructed the single-cell atlas for 11 representative species in pets, livestock, poultry, and wildlife. Notably, the proportion of SARS-CoV-2 target cells in cat was found considerably higher than other species we investigated and SARS-CoV-2 target cells were detected in multiple cell types of domestic pig, implying the necessity to carefully evaluate the risk of cats during the current COVID-19 pandemic and keep pigs under surveillance for the possibility of becoming intermediate hosts in future coronavirus outbreak. Furthermore, we screened the expression patterns of receptors for 144 viruses, resulting in a comprehensive atlas of virus target cells. Taken together, our work provides a novel and fundamental strategy to screen virus target cells and susceptible species, based on single-cell transcriptomes we generated for domesticated animals and wildlife, which could function as a valuable resource for controlling current pandemics and serve as an early warning system for coping with future infectious disease threats.

COVID-19 receptor ACE2 is expressed in human conjunctival tissue, expecially in diseased conjunctival tissue (preprint)

COVID-19 virus has currently caused major outbreaks worldwide. ACE2 is a major cellular-entry receptor for the COVID-19 virus. Although ACE2 is known to be expressed in many organs, whether it is expressed by the conjunctival tissue is largely unknown. Human conjunctival tissues from 68 subjects were obtained, which included 10 subjects with conjunctival nevi, 20 subjects with conjunctivitis, 9 subjects with conjunctival papilloma, 16 subjects with conjunctival cyst, 7 subjects with conjunctival polyps, and 6 ocular traumas as normal subjects. Expression of ACE2 was evaluated by immunohistochemistry, immunofluorescence, reverse transcriptase-quantitative polymerase chain reaction, and western blot assay. We observed the expression of ACE2 by conjunctival tissues, expecially in conjunctival epithelial cells. ACE2 was significantly (p<0.001) overexpressed in conjunctival cells obtained from subjects with conjunctivitis, conjunctival nevi, conjunctival papilloma, conjunctival cyst, and conjunctival polyps epithelial cells when compared to that in conjunctival epithelial cells obtained from control subjects. Collectively, clinical features of reported COVID-19 patients combined with our results indicate that COVID-19 is likely to be transmitted through the conjunctiva.