Comparison of an immortalized human corneal epithelial cell line with Vero cells in the isolation of Herpes simplex virus-1 for the laboratory diagnosis of Herpes simplex keratitis

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.

Update on Herpes simplex keratitis management

Herpes simplex keratitis (HSK) is a common, potentially blinding condition characterised by recurrent infections of the cornea, seen by both general ophthalmologists and corneal specialists. Successful treatment of recurrences reduces disease duration, prevents progressive corneal scaring leading to vision loss and reduces risk of further recurrences. In this review we discuss the relative advantages of the diagnostic laboratory investigations including polymerase chain reaction, viral culture and fluorescence-based immunohistochemistry. We review treatment strategies in selected aspects of HSK and discuss the management options in cases not responding to treatment.

Herpes Simplex Virus and Varicella-Zoster Virus

The most common specimens from immunocompromised patients that are analyzed for detection of herpes simplex virus (HSV) or varicella-zoster virus (VZV) are from skin lesions. Many types of assays are applicable to these samples, but some, such as virus isolation and direct fluorescent antibody testing, are useful only in the early phases of the lesions. In contrast, nucleic acid (NA) detection methods, which generally have superior sensitivity and specificity, can be applied to skin lesions at any stage of progression. NA methods are also the best choice, and sometimes the only choice, for detecting HSV or VZV in blood, cerebrospinal fluid, aqueous or vitreous humor, and from mucosal surfaces. NA methods provide the best performance when reliability and speed (within 24 hours) are considered together. They readily distinguish the type of HSV detected or the source of VZV detected (wild type or vaccine strain). Nucleic acid detection methods are constantly being improved with respect to speed and ease of performance. Broader applications are under study, such as the use of quantitative results of viral load for prognosis and to assess the efficacy of antiviral therapy.

West Nile Virus Infection in Human and Mouse Cornea Tissue

The purpose of this study was to determine the in vitro and ex vivo susceptibility of human corneal cells to West Nile virus (WNV) infection and evaluate the ability of the virus to disseminate to the corneas of infected mice. Human corneal epithelial cells were challenged with WNV, incubated for 1-6 days, and tested for evidence of WNV infection. Viral RNA and antigen were detected at every time point, and the virus reached a peak titer of 2.5 × 10⁷ plaque-forming units (pfu)/mL at 3 days postinoculation (PI). Corneas procured from donors were incubated in culture dishes containing WNV for 1-5 days and tested for evidence of WNV. Viral RNA and antigen were detected, and the virus reached a mean peak titer of 4.9 × 10⁴ pfu/mL at 5 days PI. Mice were inoculated intraperitoneally with WNV, and their eyes were harvested at 2, 5, and 8 days PI and tested for evidence of WNV. Viral RNA was detected in corneas of four of nine systemically infected mice as early as 2 days PI. We conclude that human corneal cells support WNV replication in vitro and ex vivo, and WNV may disseminate into the corneas of experimentally infected mice. These findings indicate that corneal transmission cannot be ruled out as a novel mode of human-to-human WNV transmission and additional experiments should be conducted to assess this risk further.

Application of McCoy Cell Line for Propagation of Herpes Simplex Virus Type 1

Herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) are members of the Herpesviridae family. About 40% to 80% of the world populations are infected with HSV and its prevalence is high in Iran. The high prevalence of this virus in the community and the ability of the virus in causing fatal diseases among immunocompromised patients, have encouraged studies to be performed on HSV and suitable cell lines which supports the propagation of HSV. The aim of this study was to evaluate the suitability of McCoy cell line in the isolation and propagation of HSV. An isolated wild-type HSV-1 was obtained from the labial vesicles of a 29-year-old patient who was referred to Ghaem Hospital (Mashhad, Iran). The virus was inoculated in McCoy cell monolayer cells and its titer was calculated by 50% tissue culture infectious dose (TCID50) method. Cytopathic effects (CPE) of HSV on McCoy cells appeared about 20 hours after the infection of cells. Titer of the virus was 10(-5.25) TCID50/ml. Our data showed that the McCoy cell line supported the propagation of HSV in high titer. This was the first study that used McCoy cell line for the isolation and propagation of HSV-1. McCoy cell line could be used, as a proper cell line of HSV, for various studies in the future.

Herpes simplex virus: isolation, cytopathological characterization and antiviral sensitivity

BACKGROUND

Herpes simplex virus (HSV) infection is an endemic disease and it is estimated that 6095% of the adult population are infected with symptoms that are usually self-limiting, though they can be serious, extensive and prolonged in immunocompromised individuals, highlighted by the emergence of drug-resistant strains. The study of the wild-type HSV strains based on the cytopathogenic features and its antiviral sensitivity are important in the establishment of an antivirogram for controlling the infection.

OBJECTIVE

This study sought to isolate and examine the cytopathological characteristics of circulating strains of the Herpes simplex virus, from clinical specimens and their sensitivity to commercially available antiherpesvirus drugs, acyclovir, phosphonophormic acid and trifluridine.

METHODS

Herpes simplex virus isolation, cytopathological features and antiviral sensitivity assays were performed in cell culture by tissue culture infectious dose or plaque forming unit assay.

RESULTS

From twenty-two clinical specimens, we isolated and adapted nine strains. Overall, the cytopathic effect was detected 24 h post-infection (p.i.) and the presence of syncytia was remarkable 48 h p.i., observed after cell staining. Out of eight isolates, four developed plaques of varying sizes. All the isolates were sensitive to acyclovir, phosphonophormic and trifluridine, with the percentage of virus inhibition (%VI) ranging from 49.7-100%.

CONCLUSIONS

The methodology for HSV isolation and characterization is a straightforward approach, but the drug sensitivity test, regarded as being of great practical importance, needs to be better understood.

Incidence and microbiological profile of mycotic keratitis in a tertiary care eye hospital: A retrospective analysis

PURPOSE

To determine the incidence and microbiological profile of mycotic keratitis seen at a tertiary care eye hospital.

MATERIALS AND METHODS

A retrospective review of microbiology records of patients presenting with suspected microbial keratitis seen between January 2006 and December 2009 was performed. Patients with positive fungal cultures were further analyzed for the type of fungus isolated and associated bacterial pathogens.

RESULTS

Microbiology records of 2300 patients with suspected microbial keratitis were reviewed. A microbiological diagnosis of mycotic keratitis was established in 87 (3.8%) patients over a four year period based on positive fungal cultures. The yearly incidence of mycotic keratitis was 3.2% (2006), 4.9% (2007), 3.3% (2008) and 3.6% (2009). Filamentous fungi were isolated more often than yeasts. Aspergillus species followed by Fusarium species and Trichophyton species were the commonest filamentous fungi isolated while Candida albicans was the most frequently encountered yeast. Mixed infections due to fungal and bacterial pathogens were seen in 25/87 (28.7%) patients.

CONCLUSION

Cumulative incidence of mycotic keratitis was 3.8% over a four year period. Aspergillus species and Candida albicans were the most frequent pathogenic organisms causing mycotic keratitis in this part of the world. Mixed infections were seen in 28.7% of the patients. Knowledge of the "local" etiology within a region may be valuable in the management of mycotic keratitis in instituting an empirical therapy, especially when facilities for microscopy, cultures and antifungal susceptibility are not readily available. The baseline information presented will also be helpful in the planning of a corneal ulcer management strategy and for future studies on mycotic keratitis.

Investigative modalities in infectious keratitis

Standard recommended guidelines for diagnosis of infectious keratitis do exist. Based on an extensive Medline literature search, the various investigative modalities available for aiding the diagnosis of microbial keratitis have been reviewed and described briefly. Preferred practice patterns have been outlined and the importance of routine pre-treatment cultures in the primary management of infectious keratitis has been highlighted. Corneal scraping, tear samples and corneal biopsy are few of the specimens needed to carry out the investigative procedures for diagnosis and for initiating therapy in cases of microbial keratitis. In bacterial, fungal and amoebic keratitis, microscopic examination of smears is essential for rapid diagnosis. Potassium hydroxide (KOH) wet mount, Gram's stain and Giemsa stain are widely used and are important for clinicians to start empirical therapy before microbial culture results are available. The usefulness of performing corneal cultures in all cases of suspected infectious keratitis has been well established. In cases of suspected viral keratitis, therapy can be initiated on clinical judgment alone. If a viral culture is needed, scrapings should directly be inoculated into the viral transport media. In vivo confocal microscopy is a useful adjunct to slit lamp bio-microscopy for supplementing diagnosis in most cases and establishing early diagnosis in many cases of non-responding fungal and amoebic keratitis. This is a non-invasive, high resolution technique which allows rapid detection of Acanthamoeba cysts and trophozoites and fungal hyphae in the cornea long before laboratory cultures give conclusive results. Other new modalities for detection of microbial keratitis include molecular diagnostic techniques like polymerase chain reaction, and genetic finger printing by pulsed field gel electrophoresis.