LOW VULNERABILITY OF THE POSTERIOR EYE SEGMENT TO SARS-COV-2 INFECTION: Chorioretinal SARS-CoV-2 Vulnerability.

PURPOSE: Retinal manifestations have been described in COVID-19 patients, but it is unknown whether SARS-CoV-2, the causal agent in COVID-19, can directly infect posterior ocular tissues. Here, we investigate SARS-CoV-2 host factor gene expression levels and their distribution across retinal and choroidal cell types. METHODS: Query of single-cell RNA sequencing data from human retina and choroid. RESULTS: We find no relevant expression of two key genes involved in SARS-CoV-2 entry, ACE2 and TMPRSS2, in retinal cell types. By contrast, scarce expression levels could be detected in choroidal vascular cells. CONCLUSION: Given the current understanding of viral host cell entry, these findings suggest a low vulnerability of the posterior eye segment to SARS-CoV-2 with a potential weak spot in the vasculature, which could play a putative causative role in ocular lesions in COVID-19 patients. This may qualify the vasculature of the human posterior eye segment as an in vivo biomarker for life-threatening vascular occlusions in COVID-19 patients.

Medium optimization and characterization of cell culture system from Penaeus vannamei for adaptation of white spot syndrome virus (WSSV).

The lack of shrimp cell lines and difficulty in establishing shrimp cell culture systems, with an appropriate medium is a major concern in the aquaculture sector. The present study attempts to address this issue by developing an in vitro cell culture system from various tissues (hemocytes, heart, lymphoid tissue, hepatopancreas, gill, eye stalk, and muscle) of Penaeus vannamei (P.vannamei) using commercially available L-15 medium. The cell culture medium was formulated using five different media such as HBSCM-1, HBSCM-2, HBSCM-3, HBSCM-4, and HBSCM-5 containing L-proline and glucose with fetal bovine serum (FBS) supplements. Among the different media used, the HBSCM-5 medium with supplements showed good attachment and proliferation of cells with fibroblast-like, epithelioid, round, and adherent cell morphology in hemocyte culture. The same medium was further screened using different tissues to enhance the cell growth. The hemocytes, heart, and lymphoid tissue cells were passaged five times and maintained up to 20 days. Hepatopancreas and gill cells initially showed good morphological features and survived for more than ten days following subculture cells. Eye stalks and muscle cells perished within five days and did not show any unique morphology. The primary hemocyte cells were subjected to species identification, using cytochrome oxidase subunit I (COI) gene. To assess the primary hemocyte cell culture, cells were used for in vitro propagation of white spot syndrome virus (WSSV) and confirmed by the conventional polymerase chain reaction (PCR). Similarly, the primary cells were treated with bacterial extracellular products (ECPs) from Vibrio parahaemolyticus and Vibrio harveyi, to evaluate the cytotoxicity.

A UNIQUE POSTERIOR SEGMENT PHENOTYPIC MANIFESTATION OF COXSACKIE VIRUS INFECTION.

PURPOSE: To report a posterior segment phenotypic manifestation of Coxsackie virus infection that has not been previously appreciated. METHODS: The clinical course and multimodal imaging findings, including spectral domain optical coherence tomography, fluorescein angiography, near infrared reflectance, and fundus autofluorescence of two patients with Coxsackie virus infections were documented. RESULTS: A neurosensory macular detachment was present in both patients on baseline examination. Fluorescein angiography demonstrated pooling within this lesion and spectral domain optical coherence tomography identified thickening of the retinal pigment epithelial band with variable degrees of attenuation of the ellipsoid zone and interdigitation zone. Fundus autofluorescence and near infrared reflectance imaging revealed multiple satellite lesions adjacent to the neurosensory detachment. These lesions were not seen on fluorescein angiography or color photography. Satellite lesions were hyporeflective on near infrared reflectance imaging and hyperautofluorescent on fundus autofluorescence imaging. The satellite lesions correlated with sites of ellipsoid disruption on spectral domain optical coherence tomography. Both patients were observed and their condition improved over the course of time. There was total resolution of satellite lesions, reconstitution of the ellipsoid zone and interdigitation zone, and return of retinal pigment epithelial thickness to the normal range. A bull's eye pattern of macular retinal pigment epithelial disturbance persisted on color and near infrared reflectance images, despite good visual acuity. CONCLUSION: Posterior segment Coxsackie virus infection may concurrently express the clinical characteristics of acute idiopathic maculopathy and multifocal retinitis. The visual prognosis in this variant is usually favorable. The multimodal imaging features that characterize this entity should be recognized to avoid confusion with other diseases that have a similar presentation.

Interferon-gamma, macrophages, and virus spread after HSV-1 injection.

PURPOSE: After uniocular anterior chamber (AC) injection of HSV-1, the anterior segment of BALB/c mice becomes inflamed and infected; however, virus does not spread from the anterior segment to cause retinitis in the injected eye. The purpose of these studies was to determine whether interferon (IFN-)-γ and Mac-1(+) cells play a role in preventing direct anterior-to-posterior spread of HSV-1 in the injected eye. METHODS: One AC of adult female BALB/c mice was injected with HSV-1 (KOS). The location of IFN-α, IFN-ß, and IFN-γ in the injected eye was determined by immunofluorescence, and mRNA expression was quantified by qPCR. Injected eyes of IFN-γ knockout or clodronate-treated macrophage-depleted mice were examined to determine whether the absence of IFN-γ or Mac-1(+) macrophages affected the sites or timing of virus spread. RESULTS: IFN-α, IFN-ß, and IFN-γ were observed in the anterior segment of injected eyes through 72 hours and mRNA levels of IFN-ß and IFN-γ were increased in virus-infected eyes 48 to 120 hours after infection. However, the absence of IFN-γ or macrophages did not affect either the sites or the timing of HSV-1 infection in injected eyes. CONCLUSIONS: Protection of the retina of the injected eye does not depend on a single cell type or cytokine. In addition, in the eye, as in other sites of the body, there are redundancies in the innate response to virus infection.