Tropism, replication competence, and innate immune responses of the coronavirus SARS-CoV-2 in human respiratory tract and conjunctiva: an analysis in ex-vivo and in-vitro cultures

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in December 2019, causing a respiratory disease (coronavirus disease 2019, COVID-19) of varying severity in Wuhan, China, and subsequently leading to a pandemic. The transmissibility and pathogenesis of SARS-CoV-2 remain poorly understood. We evaluate its tissue and cellular tropism in human respiratory tract, conjunctiva, and innate immune responses in comparison with other coronavirus and influenza virus to provide insights into COVID-19 pathogenesis.

METHODS

We isolated SARS-CoV-2 from a patient with confirmed COVID-19, and compared virus tropism and replication competence with SARS-CoV, Middle East respiratory syndrome-associated coronavirus (MERS-CoV), and 2009 pandemic influenza H1N1 (H1N1pdm) in ex-vivo cultures of human bronchus (n=5) and lung (n=4). We assessed extrapulmonary infection using ex-vivo cultures of human conjunctiva (n=3) and in-vitro cultures of human colorectal adenocarcinoma cell lines. Innate immune responses and angiotensin-converting enzyme 2 expression were investigated in human alveolar epithelial cells and macrophages. In-vitro studies included the highly pathogenic avian influenza H5N1 virus (H5N1) and mock-infected cells as controls.

FINDINGS

SARS-CoV-2 infected ciliated, mucus-secreting, and club cells of bronchial epithelium, type 1 pneumocytes in the lung, and the conjunctival mucosa. In the bronchus, SARS-CoV-2 replication competence was similar to MERS-CoV, and higher than SARS-CoV, but lower than H1N1pdm. In the lung, SARS-CoV-2 replication was similar to SARS-CoV and H1N1pdm, but was lower than MERS-CoV. In conjunctiva, SARS-CoV-2 replication was greater than SARS-CoV. SARS-CoV-2 was a less potent inducer of proinflammatory cytokines than H5N1, H1N1pdm, or MERS-CoV.

INTERPRETATION

The conjunctival epithelium and conducting airways appear to be potential portals of infection for SARS-CoV-2. Both SARS-CoV and SARS-CoV-2 replicated similarly in the alveolar epithelium; SARS-CoV-2 replicated more extensively in the bronchus than SARS-CoV. These findings provide important insights into the transmissibility and pathogenesis of SARS-CoV-2 infection and differences with other respiratory pathogens.

FUNDING

US National Institute of Allergy and Infectious Diseases, University Grants Committee of Hong Kong Special Administrative Region, China; Health and Medical Research Fund, Food and Health Bureau, Government of Hong Kong Special Administrative Region, China.

A controlled trial of povidone-iodine to treat infectious conjunctivitis in children

PURPOSE

To report the efficacy of povidone-iodine as a treatment for conjunctivitis in pediatric patients.

DESIGN

Double-masked, controlled, prospective clinical trial.

METHODS

In an ophthalmology clinic in a general hospital in Manila, Philippines, 459 children (mean [SD] age 6.6 [6.6] years; range, 7 months-21 years) with acute conjunctivitis were studied. Infected eyes were cultured for bacteria and underwent immunofluorescent testing for Chlamydia trachomatis. Viral conjunctivitis was diagnosed if bacterial cultures were negative and diagnostic criteria were met. Subjects were alternated to receive povidone-iodine 1.25% or neomycin-polymyxin-B-gramicidin ophthalmic solution, one drop 4 times daily in the affected eye. Ocular inflammation was evaluated daily by the family or patient and weekly by an ophthalmologist. The main outcome measures were days until cured and proportion cured after 1 and 2 weeks of treatment.

RESULTS

Despite adequate statistical power (power >80% for a 1-day difference and P <.05), there was no significant difference between treatment groups regarding the number of days to cure or proportion cured at 1 or 2 weeks whether caused by bacteria or virus (P =.133-.824 for the four comparisons). After 1 week of treatment, povidone-iodine cured marginally more chlamydial infections than the antibiotic (P =.057). By 2 weeks, fewer chlamydial infections were cured than those of viral or bacterial etiology (P =.0001). The younger the patient, the faster their conjunctivitis resolved (R = 0.13, P =.013).

CONCLUSIONS

Povidone-iodine 1.25% ophthalmic solution was as effective as neomycin-polymyxin B-gramicidin for treating bacterial conjunctivitis, somewhat more effective against chlamydia, and as ineffective against viral conjunctivitis. Povidone-iodine ophthalmic solution should be strongly considered as treatment for bacterial and chlamydial conjunctivitis, especially in developing countries where topical antibiotics are often unavailable or costly.

Co-expression of SARS-CoV-2 entry genes in the superficial adult human conjunctival, limbal and corneal epithelium suggests an additional route of entry via the ocular surface

PURPOSE

The high infection rate of SARS-CoV-2 necessitates the need for multiple studies identifying the molecular mechanisms that facilitate the viral entry and propagation. Currently the potential extra-respiratory transmission routes of SARS-CoV-2 remain unclear.

METHODS

Using single-cell RNA Seq and ATAC-Seq datasets and immunohistochemical analysis, we investigated SARS-CoV-2 tropism in the embryonic, fetal and adult human ocular surface.

RESULTS

The co-expression of ACE2 receptor and entry protease TMPRSS2 was detected in the human adult conjunctival, limbal and corneal epithelium, but not in the embryonic and fetal ocular surface up to 21 post conception weeks. These expression patterns were corroborated by the single cell ATAC-Seq data, which revealed a permissive chromatin in ACE2 and TMPRSS2 loci in the adult conjunctival, limbal and corneal epithelium. Co-expression of ACE2 and TMPRSS2 was strongly detected in the superficial limbal, corneal and conjunctival epithelium, implicating these as target entry cells for SARS-CoV-2 in the ocular surface. Strikingly, we also identified the key pro-inflammatory signals TNF, NFKβ and IFNG as upstream regulators of the transcriptional profile of ACE2+TMPRSS2+ cells in the superficial conjunctival epithelium, suggesting that SARS-CoV-2 may utilise inflammatory driven upregulation of ACE2 and TMPRSS2 expression to enhance infection in ocular surface.

CONCLUSIONS

Together our data indicate that the human ocular surface epithelium provides an additional entry portal for SARS-CoV-2, which may exploit inflammatory driven upregulation of ACE2 and TMPRSS2 entry factors to enhance infection.

Ocular surface manifestations of coronavirus disease 2019 (COVID-19): A systematic review and meta-analysis

Purpose

This study was performed to determine the occurrence of ocular surface manifestations in patients diagnosed with coronavirus disease 2019 (COVID-19) due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Methods

A systematic search of electronic databases i.e. PubMed, Web of Science, CINAHL, OVID and Google scholar was performed using a comprehensive search strategy. The searches were current through 31st May 2020. Pooled data from cross-sectional studies was used for meta-analysis and a narrative synthesis was conducted for studies where a meta-analysis was not feasible.

Results

A total of 16 studies reporting 2347 confirmed COVID-19 cases were included. Pooled data showed that 11.64% of COVID-19 patients had ocular surface manifestations. Ocular pain (31.2%), discharge (19.2%), redness (10.8%), and follicular conjunctivitis (7.7%) were the main features. 6.9% patients with ocular manifestations had severe pneumonia. Viral RNA was detected from the ocular specimens in 3.5% patients.

Conclusion

The most common reported ocular presentations of COVID-19 included ocular pain, redness, discharge, and follicular conjunctivitis. A small proportion of patients had viral RNA in their conjunctival/tear samples. The available studies show significant publication bias and heterogeneity. Prospective studies with methodical collection and data reporting are needed for evaluation of ocular involvement in COVID-19.

Role of the Eye in Transmitting Human Coronavirus: What We Know and What We Do Not Know

The outbreak of the current 2019 novel coronavirus (2019-nCoV, now named SARS-CoV-2) infection has become a worldwide health threat. Currently, more information is needed so as to further understand the transmission and clinical characteristics of 2019-nCoV infection and the infection control procedures required. Recently, the role of the eye in transmitting 2019-nCoV has been intensively discussed. Previous investigations of other highly infectious human CoVs, that is, severe acute respiratory syndrome coronavirus (SARS-CoV) and the Middle East respiratory syndrome coronavirus (MERS-CoV), may provide useful information. In this review, we describe the genomics and morphology of human CoVs, the epidemiology, systemic and ophthalmic manifestations, and mechanisms of human CoV infection, and recommendations for infection control procedures. The role of the eye in the transmission of 2019-nCoV is discussed in detail. Although the conjunctiva is directly exposed to extraocular pathogens, and the mucosa of the ocular surface and upper respiratory tract are connected by the nasolacrimal duct and share the same entry receptors for some respiratory viruses, the eye is rarely involved in human CoV infection, conjunctivitis is quite rare in patients with 2019-nCoV infection, and the CoV RNA positive rate by RT-PCR test in tears and conjunctival secretions from patients with 2019-nCoV and SARS-CoV infection is also extremely low. This suggests that the eye is neither a preferred organ of human CoV infection nor a preferred gateway of entry for human CoVs for infecting the respiratory tract. However, pathogens that the ocular surface is exposed to might be transported to nasal and nasopharyngeal mucosa by constant tear rinsing through the lacrimal duct system and then cause respiratory tract infection. Considering that close doctor-patient contact is quite common in ophthalmic practice and is apt to transmit human CoVs by droplets and fomites, strict hand hygiene and proper personal protection are highly recommended for health care workers to avoid hospital-related viral transmission during ophthalmic practice.

Prevalence of SARS-CoV-2 in human post-mortem ocular tissues

BACKGROUND

SARS-CoV-2 is found in conjunctival swabs and tears of COVID-19 patients. However, the presence of SARS-CoV-2 has not been detected in the human eye to date. We undertook this study to analyze the prevalence of SARS-CoV-2 in human post-mortem ocular tissues.

METHODS

The expression of SARS-CoV-2 RNA was assessed by RT-PCR in corneal and scleral tissues from 33 surgical-intended donors who were eliminated from a surgical use per Eye Bank Association of America (EBAA) donor screening guidelines or medical director review or positive COVID-19 test. Ocular levels of SARS-CoV-2 RNA (RT-PCR), Envelope and Spike proteins (immunohistochemistry) and anti-SARS-CoV-2 IgG and IgM antibodies (ELISA) in blood were evaluated in additional 10 research-intent COVID-19 positive donors.

FINDINGS

Of 132 ocular tissues from 33 surgical-intended donors, the positivity rate for SARS-CoV-2 RNA was ~13% (17/132). Of 10 COVID-19 donors, six had PCR positive post-mortem nasopharyngeal swabs whereas eight exhibited positive post-mortem anti-SARS-CoV-2 IgG levels. Among 20 eyes recovered from 10 COVID-19 donors: three conjunctival, one anterior corneal, five posterior corneal, and three vitreous swabs tested positive for SARS-CoV-2 RNA. SARS-CoV-2 spike and envelope proteins were detected in epithelial layer of the corneas that were procured without Povidone-Iodine (PVP-I) disinfection.

INTERPRETATIONS

Our study showed a small but noteworthy prevalence of SARS-CoV-2 in ocular tissues from COVID-19 donors. These findings underscore the criticality of donor screening guidelines, post-mortem nasopharyngeal PCR testing and PVP-I disinfection protocol to eliminate any tissue harboring SARS-CoV-2 being used for corneal transplantation.

Human papilloma virus in neoplastic and non-neoplastic conditions of the external eye

AIM

Human papilloma virus (HPV) types 16 and 18 have been associated with neoplastic conditions of the conjuctiva. However, the presence of this virus has not been reported in non-neoplastic disorders of the external eye nor has it been studied in normal conjunctival tissues.

METHODS

Ninety six paraffin embedded tissue specimens with neoplastic and non-neoplastic lesions and 19 conjunctiva samples free from overt disease were studied for HPV types 16 and 18 positivity with the polymerase chain reaction.

RESULTS

HPV types 16 and 18 DNA were identified in 57% of in situ squamous cell carcinoma, in 55% of invasive squamous cell carcinoma, in 20% of climatic droplet keratopathy, in 35% of scarred corneas, and in 32% of normal conjunctival tissue obtained during routine cataract extractions.

CONCLUSION

These findings indicate that HPV types 16 and 18 are detectable with the polymerase chain reaction not only in epithelial neoplasms of the ocular mucous membrane but also in non-neoplastic lesions as well as in apparently healthy conjunctiva.

Serotyping of adenoviruses on conjunctival scrapings by PCR and sequence analysis

To detect and identify adenovirus (Ad), we investigated hypervariable regions (HVRs) of Ad by using a combination of PCR and direct sequencing (PCR-sequence) method. Primers for nested PCR to amplify the conserved region in the hexon protein containing HVRs were designed based on hexon gene sequences derived from GenBank. These two primer sets amplified a DNA fragment of 7 HVRs from 16 prototypes of Ad, which were divided into five subgenera, including seven serotypes that are the predominant causative agents of acute conjunctivitis in Japan, and from 31 recent conjunctival scraping specimens from patients with adenoviral conjunctivitis. HVR DNA sequences were determined by means of universal sequence primers. Analysis of the predicted amino acid homology of HVRs among Ad prototypes suggested three regions, HVR4, -5, and -7, to be candidates for the neutralization epitopes. The clinical serotype of specimens was determined by the PCR-sequence method with reference to these three HVRs. The serotype determined according to this method was identical to that obtained by culture isolation and the neutralization test (NT) in all scraping samples, whereas the results of this method did not match PCR and restriction fragment length polymorphism (PCR-RFLP) analysis in five samples. It took only three days to detect Ad and to identify the serotype, in contrast to culture isolation-NT, which took at least 2 weeks. These findings indicate that our newly developed PCR-sequence method is applicable for the detection and serotyping of human Ads.

Transmission of SARS-CoV-2: an update of current literature

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiologic agent for the 2019 coronavirus disease (COVID-19) pandemic, has caused a public health emergency. The need for additional research in viral pathogenesis is essential as the number of cases and deaths rise. Understanding the virus and its ability to cause disease has been the main focus of current literature; however, there is much unknown. Studies have revealed new findings related to the full transmission potential of SARS-CoV-2 and its subsequent ability to cause infection by different means. The virus is hypothesized to be of increased virulence compared with previous coronavirus that caused epidemics, in part due to its overall structural integrity and resilience to inactivation. To date, many studies have discussed that the rationale behind its transmission potential is that viral RNA has unexpectedly been detected in multiple bodily fluids, with some samples having remained positive for extended periods of time. Additionally, the receptor by which the virus gains cellular entry, ACE2, has been found to be expressed in different human body systems, thereby potentiating its infection in those locations. In this evidence-based comprehensive review, we discuss various potential routes of transmission of SARS-CoV-2-respiratory/droplet, indirect, fecal-oral, vertical, sexual, and ocular. Understanding these different routes is important as they pertain to clinical practice, especially in taking preventative measures to mitigate the spread of SARS-CoV-2.

Transmission of hepatitis C by blood splash into conjunctiva in a nurse

The risk of transmission of hepatitis C virus (HCV) infection is an important problem for the health care worker. HCV transmission by blood splashing into eyes is very rare. In a hemodialyses department, a 23-year-old female nurse splashed blood from a patient who was anti-HCV positive into her eyes. She washed her eyes with water immediately and reported to the infection control department. She had never used intravenous drugs nor received transfusions. At the time of exposure, there was no abnormality in her laboratory tests. Her anti-HCV and HCV-RNA tests produced negative results. She was followed up for anti-HCV and alanine aminotransferase activity. After 6 months, she presented with sore throat, nausea, vomiting, fatigue, and weight loss. She had icterus and hepatomegalia. In laboratory tests, alanine aminotransferase level was 504 U/L, aspartate aminotransferase level was 388 U/L, and anti-HCV and HCV-RNA tests produced positive findings. She was treated with interferon alfa-2a for a 1-year period. After treatment, an HCV-RNA test produced negative results and transaminase levels were normal. In conclusion, splashing blood from patients who are HCV positive into the face or eyes is a risk for health care workers. They should be educated to prevent a nosocomial acquisition of bloodborne infection and they should observe protective precautions.

Coronavirus disease 2019 (SARS-CoV-2) and colonization of ocular tissues and secretions: a systematic review

Coronavirus disease 19 (COVID-19) has been described to potentially be complicated by ocular involvement. However, scant information is available regarding severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) and ocular structures tropism. We conducted a systematic review of articles referenced in PubMed, Cochrane Library, Web of Science and Chinese Clinical Trial Register (ChiCTR) from December 20, 2019 to April 6, 2020, providing information on the presence of SARS-CoV-2 in cornea, conjunctiva, lacrimal sac, and tears. We excluded ongoing clinical  studies as for unobtainable conclusive results. Of 2422 articles, 11 met the inclusion criteria for analysis and were included in the study. None of the studies were multinational. Among the 11 selected papers there were three original articles, one review, four letters, two editorials, and one correspondence letter. Globally, 252 SARS-CoV-2 infected patients were included in our review. The prevalence of ocular conjunctivitis complicating the course of COVID-19 was demonstrated to be as high as 32% in one study only. Globally, three patients had conjunctivitis with a positive tear-PCR, 8 patients had positive tear-PCR in the absence of conjunctivitis, and 14 had conjunctivitis with negative tear-PCR. The majority of the available data regarding SARS-CoV-2 colonization of ocular and periocular tissues and secretions have to be considered controversial. However, it cannot be excluded that SARS-CoV-2 could both infect the eye and the surrounding structures. SARS-CoV-2 may use ocular structure as an additional transmission route, as demonstrated by the COVID-19 patients' conjunctival secretion and tears positivity to reverse transcriptase-PCR SARS-CoV-2-RNA assay.

A 50-kDa membrane protein mediates sialic acid-independent binding and infection of conjunctival cells by adenovirus type 37

The ocular tropism of adenovirus type 37 (Ad37) does not correlate with the wide distribution of the 46-kDa coxsackievirus and adenovirus receptor (CAR), the major receptor for most adenovirus serotypes. We previously found that Ad37 infects and binds well to conjunctival cells (Chang C), but poorly to lung epithelial (A549) cells that express CAR and hypothesized that this serotype uses a distinct receptor that is selectively expressed on conjunctival cells. To test this, we produced particles of a fiber-deleted Ad5 vector containing the Ad37 fiber protein. The "pseudotyped" vector infected Chang C cells better than A549 cells using a CAR-independent pathway. Ad37 binding was calcium-dependent and was abolished by protease digestion of cell surface proteins. Using a virus overlay protein blot assay (VOPBA), we detected calcium-dependent Ad37 binding to 50- and 60-kDa membrane proteins on permissive Chang C cells. In contrast, calcium-dependent binding was detected with only the 60-kDa protein on nonpermissive A549 cells. Ad19p, a closely related serotype that failed to bind to conjunctival cells, recognized the 60-kDa, but not the 50-kDa, protein. Ad37 has been reported to use sialic acid instead of CAR as a cell receptor on A549 cells. Pretreatment of Chang C cells with neuraminidase abolished Ad37 binding to only the 60-kDa protein, suggesting that sialic acid mediates Ad37 binding to the 60-kDa protein. The pseudotyped Ad37 vector was also able to infect neuraminidase-treated Chang C cells. Thus, subgroup D adenoviral binding to the 50-kDa protein is calcium-dependent and cell type- and serotype-specific, whereas binding to the 60-kDa protein is not necessary for infection of conjunctival cells. Together, these data suggest that the 50-kDa protein is the major receptor for Ad37 on conjunctival cells.

Failure to detect human papillomavirus DNA in malignant epithelial neoplasms of conjunctiva by polymerase chain reaction

To elucidate the putative role of human papillomavirus (HPV) infection in the etiology of conjunctival tumors, 44 formalin-fixed, paraffin-embedded specimens of conjunctival tumors (24 patients with papillomas and 20 patients with dysplastic and/or malignant tumors) were screened for HPV infection using 4 different polymerase chain reactions (PCRs). Of the 24 samples of papilloma, 14 (58%) displayed positive results by applying nested PCR using primer sets of HPV consensus L1 region. HPV type 6 or 11 was detected in 9 cases of papilloma by type-specific primer sets, but none of them were positive for HPV type 16 or 18. However, by using the highly sensitive PCR technique, we failed to demonstrate the HPV DNA of HPV types 6, 11, 16, and 18 in any of the 20 malignant epithelial tumors of conjunctiva. We conclude that HPV-6 or HPV-11 is present in a substantial percentage of conjunctival papillomas, which is in accordance with findings of previously reported studies. In contrast, malignant conjunctival carcinomas are not associated with HPV infection; other pathogenic mechanisms, such as UV light, probably are more important in the cause of these malignant lesions.

A novel HLA (HLA-A*0201) transgenic rabbit model for preclinical evaluation of human CD8+ T cell epitope-based vaccines against ocular herpes

We introduced a novel humanized HLA-A*0201 transgenic (HLA Tg) rabbit model to assess the protective efficacy of a human CD8(+) T cell epitope-based vaccine against primary ocular herpes infection and disease. Each of the three immunodominant human CD8(+) T cell peptide epitopes from HSV-1 glycoprotein D (gD(53-61), gD(70-78), and gD(278-286)) were joined with a promiscuous human CD4(+) T cell peptide epitope (gD(49-82)) to construct three separate pairs of CD4-CD8 peptides. Each CD4-CD8 peptide pair was then covalently linked to an N(epsilon)-palmitoyl-lysine residue via a functional base lysine amino group to construct CD4-CD8 lipopeptides. HLA Tg rabbits were immunized s.c. with a mixture of the three CD4-CD8 HSV-1 gD lipopeptides. The HSV-gD-specific T cell responses induced by the mixture of CD4-CD8 lipopeptide vaccine and the protective efficacy against acute virus replication and ocular disease were determined. Immunization induced HSV-gD(49-82)-specific CD4(+) T cells in draining lymph node (DLN); induced HLA-restricted HSV-gD(53-61), gD(70-78), and gD(278-286)-specific CD8(+) T cells in DLN, conjunctiva, and trigeminal ganglia and reduced HSV-1 replication in tears and corneal eye disease after ocular HSV-1 challenge. In addition, the HSV-1 epitope-specific CD8(+) T cells induced in DLNs, conjunctiva, and the trigeminal ganglia were inversely proportional with corneal disease. The humanized HLA Tg rabbits appeared to be a useful preclinical animal model for investigating the immunogenicity and protective efficacy of human CD8(+) T cell epitope-based prophylactic vaccines against ocular herpes. The relevance of HLA Tg rabbits for future investigation of human CD4-CD8 epitope-based therapeutic vaccines against recurrent HSV-1 is discussed.

Possible consequences of shaking hands with your patients with epidemic keratoconjunctivitis

PURPOSE

We evaluated patients' hands as a possible vector for the spread of epidemic kerato-conjunctivitis.

METHODS

The hands and conjunctivitis of 26 patients with epidemic keratoconjunctivitis and the hands of 26 uninfected control patients were cultured for infectious adenovirus.

RESULTS

In 12 (46%) of 26 patients with epidemic keratoconjunctivitis, cultures from the hands were positive for adenovirus, whereas cultures from the hands of all uninfected control patients were negative.

CONCLUSIONS

Simultaneous coinfection of patients' hands and eyes with adenovirus may contribute to office epidemics. Ophthalmologists and coworkers should not shake the hands of patients suspected of having epidemic keratoconjunctivitis unless properly gloved.

HVEM and nectin-1 are the major mediators of herpes simplex virus 1 (HSV-1) entry into human conjunctival epithelium

PURPOSE

The human conjunctiva is a natural target for herpes simplex virus (HSV)-1 infection. The goals of this study were to investigate the cellular and molecular mechanisms of HSV-1 entry into human conjunctival epithelial (HCjE) cells. Specific features of entry studied included the method of initial viral binding to cells, pH dependency, and expression and usage of specific HSV-1 entry receptors.

METHODS

To observe HSV-1 initial binding, live cell imaging was performed on HSV-1-infected HCjE cells. Reporter HSV-1 virions expressing beta-galactosidase were used to determine entry of wild-type HSV-1(KOS) and a mutant, HSV-1(KOS)Rid1, into HCjE cells. HSV-1 replication in HCjE cells was determined by plaque assays. Lysosomotropic agents were used to determine whether viral entry was pH dependent. Reverse transcription (RT)-PCR, flow cytometry, and immunohistochemistry were used to determine the expression of receptors. Receptor-specific siRNAs were used to define the role of individual entry receptors.

RESULTS

HSV-1 virions attach to filopodia present on HCjE cells and use them to reach the cell body for entry. Cultured HCjE cells demonstrate susceptibility to HSV-1 entry and form plaques confirming viral replication. Blocking vesicular acidification significantly reduces entry, implicating a pH-dependent mode of entry. Multiple assays confirm the expression of entry receptors nectin-1, HVEM, and 3-O-sulfated heparan sulfate (3-OS HS) on the HCjE cell membrane. Knocking down of gD receptors by siRNAs interference implicates nectin-1 and HVEM as the major mediators of entry.

CONCLUSIONS

HSV-1 entry into HCjE cells is a pH-dependent process that is aided by targeted virus travel on filopodia. HCjE cells express all three major entry receptors, with nectin-1 and HVEM playing the predominant role in mediating entry.

A single amino acid in the adenovirus type 37 fiber confers binding to human conjunctival cells

A 46-kDa receptor, coxsackievirus-adenovirus (Ad) receptor (CAR), mediates cell attachment of a number of different Ad serotypes; however, not all Ad serotypes utilize this receptor for infection. Moreover, the precise amino acid sequences in the Ad fiber protein that mediate cell attachment have yet to be identified. We investigated the interaction of subgroup D Ads with human ocular cells. Ad serotype 37 (Ad37), a virus associated with epidemic keratoconjunctivitis, but not a closely related virus serotype, Ad19p, exhibited preferential binding to and infection of human conjunctival cells. A single amino acid substitution in the Ad19p fiber distal domain (knob), Glu240 to Lys, conferred binding to conjunctival cells, while the reverse substitution in the Ad37 fiber abrogated cell binding. These findings provide new information on the fiber sequences that regulate Ad host cell tropism.

SARS-CoV-2 on Ocular Surfaces in a Cohort of Patients With COVID-19 From the Lombardy Region, Italy

Importance

Since February 2020, coronavirus disease 2019 (COVID-19) has spread rapidly all over the world, with an epidemiological cluster in Lombardy, Italy. The viral communicability may be mediated by various body fluids, but insufficient information is available on the presence of the virus in human tears.

Objectives

To investigate the rate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in tears collected from patients with COVID-19 by means of real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) assay and to assess the association of virus presence with concomitant clinical conditions.

Design, Setting, and Participants

Cross-sectional study conducted between April 9 and May 5, 2020. The setting was intensive care units at Azienda Socio-Sanitaria Territoriale (ASST) Sette-Laghi Hospital, University of Insubria, in Varese, Lombardy, Italy. A conjunctival swab was performed in 91 patients hospitalized for COVID-19, which was clinically diagnosed by rRT-PCR assay on nasopharyngeal swabs and by radiological imaging. Conjunctival swabs from 17 additional healthy volunteer participants with no symptoms of COVID-19 were examined to evaluate the availability and applicability of the conjunctival swab test.

Exposure

SARS-CoV-2 detection by means of rRT-PCR assay performed on the collected samples obtained by conjunctival swabs.

Main Outcomes and Measures

Conjunctival swab and nasopharyngeal swab results are reported, as well as demographic and clinical data.

Results

A total of 108 participants (mean [SD] age, 58.7 [14.2] years; 55 female and 53 male) were tested for SARS-CoV-2 using rRT-PCR assay, including 91 patients hospitalized with COVID-19 and 17 were healthy volunteers. SARS-CoV-2 was found on the ocular surface in 52 of 91 patients with COVID-19 (57.1%; 95% CI, 46.3%-67.5%), with a wide variability in the mean viral load from both eyes. Among a subset of 41 patients, concordance of 63.0% (95% CI, 41.0%-81.0%) was found between positive conjunctival and nasopharyngeal swab test results when performed within 2 days of each other. In 17 of these patients, nasopharyngeal swab results were negative for SARS-CoV-2. In 10 of these 17 patients, conjunctival swab results were positive for the virus.

Conclusions and Relevance

In this study, SARS-CoV-2 RNA was found on the ocular surface in a large part of this cohort of patients with COVID-19, although the infectivity of this material could not be determined. Because patients may have positive test results with a conjunctival swab and negative results with a nasopharyngeal swab, use of the slightly invasive conjunctival swab may be considered as a supplementary diagnostic test.

A novel nested PCR for the diagnosis of calicivirus infections in the cat

A novel nested PCR (nPCR) assay is reported on the diagnosis of the feline calicivirus (FCV) infection. The test was performed on 47 ocular and 40 pharyngeal swabs collected from 47 cats with respiratory syndrome; among the 87 samples examined, 18 ocular and 23 pharyngeal swabs were positive in nPCR. The nPCR sensitivity was compared to other diagnostic techniques such as virus isolation on cell culture and reverse transcriptase-polymerase chain reaction (RT-PCR). The nPCR was more sensitive than the virus isolation and RT-PCR; therefore, it can be used for calicivirosis diagnosis in cats.

PCR detection of adenovirus in a bone marrow transplant recipient: hemorrhagic cystitis as a presenting manifestation of disseminated disease

Adenoviruses (AdV), causing fatal disseminated infections in bone marrow transplant (BMT) recipients, are associated not only with hemorrhagic cystitis (HC) but also with hepatitis, conjunctivitis, and viral interstitial pneumonia. The importance of this virus as a cause of disseminated disease, however, has remained underappreciated. AdV infection has been diagnosed primarily through the use of cell culture. The fact that cell culture is insensitive for detecting this virus has hindered recognition of the role that AdV may play in morbidity and mortality in BMT recipients. To emphasize these points, we describe a patient who presented with HC due to AdV serotype 11, genotype c, and died with disseminated infection. In addition to cell culture, this study used a newly developed PCR-based method, capable of detecting all AdV serotypes tested, including different genotypes of serotype 11. The PCR result was positive in all culture-positive samples, including samples of urine, conjunctiva, and bronchoalveolar lavage (BAL). Importantly, the PCR method provided evidence of urinary shedding of AdV in a pretransplant, culture-negative specimen and showed dissemination in a subset of culture-negative specimens, including BAL, blood, and bone marrow samples. The lack of widespread awareness of the fact that localized infections may presage dissemination, and the previous associated lack of rapid, sensitive diagnostic assays, has impaired recognition of AdV infections in patients undergoing BMT. Early detection may contribute to therapy modification and avoidance of unwarranted diagnostic procedures. It may also assist in epidemiologic control of this highly infectious pathogen and lead to a renewed interest in preventive and therapeutic approaches.

High sensitivity polymerase chain reaction assay for active and latent feline herpesvirus-1 infections in domestic cats

A polymerase chain reaction (PCR) assay was developed and used to detect feline herpesvirus-1 (FHV-1) in conjunctival and oropharyngeal swabs, and in latently infected tissues (trigeminal ganglia, optic nerves, optic chiasma, olfactory bulbs and corneas) collected from 10 experimentally infected cats. There was good agreement between parallel tests of the swab specimens by PCR and virus isolation assay during the phase of acute, latent and recurrent disease episodes (kappa = 0.63, P < 0.001). The PCR reliably detected < or = 240 copies of FHV-1 template DNA, significantly improving upon previously published PCR assays for the agent.

Rapid diagnosis of adenoviral conjunctivitis on conjunctival swabs by 10-minute immunochromatography

PURPOSE

Several methods are available for the diagnosis of acute conjunctivitis, all of which are time-consuming or require the use of a well-equipped laboratory. A new method, immunochromatography (IC), for detecting the presence of adenovirus (Ad) has been developed. Two direct rapid tests to detect Ad antigen, IC and enzyme immunoassay (EIA), were compared with regard to sensitivity, specificity, and technical complexity.

METHODS

The study materials consisted of 130 swabs from patients with conjunctivitis (95 samples of adenoviral conjunctivitis proven by positive virus DNA on polymerase chain reaction [PCR], 35 samples of nonadenoviral conjunctivitis proven by PCR). IC is a one-step procedure that detects the presence of adenoviral antigen by sandwich EIA on a paper disc.

RESULTS

In 95 adenoviral DNA-positive samples by PCR, the sensitivity and specificity of IC were 54.7% and 97.1%, respectively, whereas those of EIA were 50.5% and 100%, respectively. By IC, PCR-positive Ad type 3 was recognized in 31%; Ad4 in 100%; Ad7 in 60%; Ad8 in 67%; and Ad37 in 59%, showing similar positivity rates for different serotypes (except Ad7) to those using EIA. Visual determination of the presence of Ad took an average of 10 minutes by IC compared with 70 minutes by EIA.

CONCLUSIONS

These results indicate that IC is a more rapid and easier test compared with EIA, and it has high specificity. Detection of Ad antigen by this simple and rapid method will serve physicians as a useful tool for early diagnosis and prevention of adenoviral conjunctivitis.

Persistence of Zika virus in conjunctival fluid of convalescence patients

A widespread epidemic of Zika fever, caused by Zika virus (ZIKAV) has spread throughout the Pacific islands, the Americas and Southeast Asia. The increased incidences of ocular anomalies observed in ZIKAV-infected infants and adults may be associated with the rapid spread of ZIKAV. The objective of this study was to check if ZIKAV could be detected in human tears after the first week of infection. Twenty-nine patients with PCR confirmed ZIKAV infection during the Singapore August 2016 ZIKAV outbreak were enrolled for the study. Detection and quantification of ZIKAV RNA was performed on conjunctival swabs collected from both eyes of these patients at the late convalescent phase (30 days post-illness). Efficiency of viral isolation from swab samples was confirmed by the limit of detection (as low as 0.1 PFU/µL, equivalent to copy number of 4.9) in spiked swabs with different concentrations of ZIKAV (PFU/µL). Samples from three patients were found positive by qRT-PCR for ZIKAV and the viral RNA copy numbers detected in conjunctival swabs ranged from 5.2 to 9.3 copies respectively. ZIKAV could persist in the tears of infected patients for up to 30 days post-illness, and may therefore possess a potential public health risk of transmission.