Tear and serum antibody levels in ocular herpetic infection: diagnostic precision of secretory IgA

Atypical stromal herpes simplex keratitis: clinical features and diagnosis

PURPOSE

To report atypical clinical features and diagnosis of stromal herpes simplex keratitis (HSK) and to evaluate the diagnostic efficiency of tear HSV-sIgA in atypical HSK.

STUDY DESIGN

Prospective observational study.

METHODS

Records of keratitis' patients with tear herpes simplex virus (HSV)-sIgA test results acquired between May 2019 and November 2021 were evaluated retrospectively. Positive tear HSV-sIgA test was used to identify herpes simplex virus (HSV) infection. Patients with typical presentations and histories of HSV keratitis (HSK) were excluded.

RESULTS

Eleven eyes of 11 patients initially diagnosed as keratitis caused by other etiology were confirmed as having HSV infection by positive results of tear HSV-sIgA. Clinical features of atypical stromal HSK were variable. Antiviral treatment was effective in all patients.

CONCLUSION

The appearance of an atypical stromal HSK represents a diagnostic challenge. Tear HSV-sIgA test could help provide a quick diagnosis.

SARS-CoV-2 RNA and antibodies in tear fluid

Background/aims

SARS-CoV-2 is highly contagious. More evidence concerning extrapulmonary transmission routes such as the eyes is urgently needed. Although the humoral immune response is important in the viral containment, the local response in tears has not yet been studied. The aim of our study was twofold: to assess the prevalence of both SARS-CoV-2 RNA and antibodies in tear fluid.

Methods

In a first series, nasopharyngeal sampling and tear sampling by Schirmer test strips were performed in 26 acutely ill patients with COVID-19 to assess the presence of SARS-CoV-2 RNA by reverse transcription PCR. In a second series, IgG and IgA responses to SARS-CoV-2 spike protein in serum and tear fluid of convalescent individuals (n=22) were compared with control individuals (n=15) by ELISA.

Results

SARS-CoV-2 RNA was detected in tears of 7/26 (26.9%) patients with COVID-19. None of them had ocular symptoms. Convalescent individuals displayed a significant higher ratio of IgG (p<0.0001) and IgA (p=0.0068) in tears compared with control individuals. A sensitivity of 77.3% and specificity of 93.3% was observed for IgG, and 59.1% and 100% for IgA.

Conclusions

Our results demonstrate the presence of SARS-CoV-2 RNA and a local IgG and IgA immune response in tear fluid. These data confirm the possibility of SARS-CoV-2 transmission through tear fluid and the importance of the eye as a first defence against SARS-CoV-2, indicating the potential of tears as a non-invasive surrogate for serum in monitoring the host immune response.

A systematic review on advances in diagnostics for herpes simplex keratitis

Herpes simplex keratitis (HSK) is a significant cause of vision impairment worldwide. Currently, there are no set diagnostic criteria, and popular diagnostic methods, including clinical examination of the eye via slit lamp examination, could lead to false-negatives and misdiagnoses. Molecular testing with polymerase chain reaction (PCR) may lack concordance with clinical findings, posing a great challenge to ophthalmologists. We evaluate recent studies on techniques for the diagnosis of HSK. We included a total of 23 studies published between 2010 and 2020 in English on diagnostic techniques, including in vivo confocal microscopy, polymerase PCR testing, protein detection in tear film with enzyme-linked immunosorbent assay, and various other protein assays. Although PCR has been widely used as one of the current diagnostic methods for HSK, most studies evaluated its efficacy after including alterations to its normal protocol. Tear sample analysis was performed using multiple tools, although corneal scrapings demonstrated a higher positive detection rate. Diagnostic tools identified were able to detect HSK with varying accuracy. Newer diagnostic techniques like multiplex dot hybridization assay and immunochromatographic assays may be considered as the point-of-care preliminary diagnostic tools. More reliable results may be generated by developing a standardized diagnostic protocol.

Antibody detection in tear samples as a surrogate to monitor host immunity against papillomavirus infections in vaccinated and naturally infected hosts

Monitoring serum antibodies against natural infections or after immunizations has been a standard clinical diagnostic procedure. However, collecting blood samples requires trained personnel, and may cause discomfort and increase the risk of complications. In this study, we investigated whether tear samples could serve as a surrogate for serum samples to measure specific antibodies. A widely used preclinical cottontail rabbit papillomavirus (CRPV)/rabbit model has been a surrogate model for high-risk human papillomavirus (HPV) infections. New Zealand white rabbits, either naturally infected with CRPV or immunized with two clinically available HPV vaccines (Gardasil and Cervarix), were examined for antibody generation in both tear and serum samples. We demonstrated that antibodies were detectable in tears from both naturally infected as well as vaccinated animals. Overall, the antibody levels in tears were ~10-fold lower than those from the corresponding serum samples, but background noise was lower in tear samples. The isotypes of antibodies in tears were predominantly IgA and IgG. These findings showed clearly that tears could be a surrogate for serum samples for monitoring antibody responses. As collecting tears causes no discomfort and poses no risk to patients, it represents a novel and promising method for monitoring future HPV epidemiological studies as well as for use in clinical practice.

Tear HSV-specific secretory IgA as a potential indicator for recurrent stromal herpes simplex keratitis: a preliminary study

PURPOSE

To assess the herpes simplex virus-specific tear secretory IgA (sIgA) and its correlation with specific serum antibodies and to evaluate the possible value of specific tear sIgA for prediction of herpes simplex keratitis (HSK) recurrence.

METHODS

Tear sIgA and paired serum IgG/IgM/IgA from 41 stromal HSK patients and 15 controls were analyzed by enzyme-linked immunosorbent assay. Subsequent follow-up for monitoring recurrence was performed from the time of first cure on all patients for 4 months to 1 year.

RESULTS

Serum IgG was positive in all participants. The concentration of serum IgA increased with the levels of tear sIgA (P = 0.017). The tear sIgA-positive rate was 36.59% in stromal keratitis, whereas none of the controls were found as sIgA positive. Positivity of sIgA was the only potential factor for predicting the risk of herpes keratitis recurrence (hazard ratio = 9.04; 95% confidence interval, 1.06-77.44; P = 0.045), with a sensitivity of 83.3% and a specificity of 71.4% (P = 0.034; 95% confidence interval, 0.58-0.97). Tear sIgA-positive patients had significantly shorter relapse-free survival compared with tear sIgA-negative patients (P = 0.015).

CONCLUSIONS

This is the first preliminary study suggesting that the levels of tear sIgA could be a potential prognostic parameter for the recurrence of HSK.

Rotavirus specific plasma secretory immunoglobulin in children with acute gastroenteritis and children vaccinated with an attenuated human rotavirus vaccine

Rotavirus (RV)-specific secretory immunoglobulin (RV-SIg) has been previously detected in serum of naturally RV infected children and shown to reflect the intestinal Ig immune response. Total plasma SIgA and plasma RV-SIg were evaluated by ELISA in children with gastroenteritis due or not due to RV infection and in 50 children vaccinated with the attenuated RIX4414 human RV vaccine and 62 placebo recipients. RV-SIg was only detected in children with evidence of previous RV infection or with acute RV gastroenteritis. Vaccinees had higher RV-SIg titers than placebo recipients and RV-SIg titers increased after the second vaccine dose. RV-SIg measured after the second dose correlated with protection when vaccinees and placebo recipients were analyzed jointly. RV-SIg may serve as a valuable correlate of protection for RV vaccines.

Cytomegalovirus antibodies in tear fluid of patients with retinitis

The diagnosis of cytomegalovirus retinitis (CMV-R) is difficult and usually based on clinical criteria or invasive diagnostic procedures. The purpose of this study was to investigate a possible association between CMV-R and specific anti-CMV antibodies in tears. Paired tear and serum samples were obtained from 96 individuals, which included 20 children with congenital CMV infection and chorioretinitis, 56 adults with retinitis with clinical signs suggestive of viral infection, and 20 healthy control subjects, and were tested for CMV antibodies using ELISA. The prevalence of anti-CMV antibodies in tears was found to be 80% (16/20) in children, 35% (20/56) in adults, and 5% (1/20) in control subjects. Furthermore, high antibody levels were detected in 35% (7/20) of children and 10.7% (6/56) of adults with retinitis, and were not found in control subjects. There was a strong association between high tear levels of anti-CMV antibodies and active ocular infection. No correlations were found between tear and serum antibodies. ELISA sensitivity was 80% and specificity 95%. Further studies are needed to compare the tear and intraocular levels of CMV-specific antibodies in patients with retinitis to find out if CMV antibody testing in tear fluid could substitute for more invasive diagnostic procedures.

The immune response to ocular herpes simplex virus type 1 infection

Herpes simplex virus type 1 (HSV-1) is a prevalent microbial pathogen infecting 60% to 90% of the adult world population. The co-evolution of the virus with humans is due, in part, to adaptations that the virus has evolved to aid it in escaping immune surveillance, including the establishment of a latent infection in its human host. A latent infection allows the virus to remain in the host without inducing tissue pathology or eliciting an immune response. During the acute infection or reactivation of latent virus, the immune response is significant, which can ultimately result in corneal blindness or fatal sporadic encephalitis. In fact, HSV-1 is one of the leading causes of infectious corneal blindness in the world as a result of chronic episodes of viral reactivation leading to stromal keratitis and scarring. Significant inroads have been made in identifying key immune mediators that control ocular HSV-1 infection and potentially viral reactivation. Likewise, viral mechanisms associated with immune evasion have also been identified and will be discussed. Lastly, novel therapeutic strategies that are currently under development show promise and will be included in this review. Most investigators have taken full advantage of the murine host as a viable working in vivo model of HSV-1 due to the sensitivity and susceptibility to viral infection, ease of manipulation, and a multitude of developed probes to study changes at the cellular and molecular levels. Therefore, comments in this review will primarily be restricted to those observations pertaining to the mouse model and the assumption (however great) that similar events occur in the human condition.

Wolfring dacryops

BACKGROUND

A unique series of 13 cases of ductal cysts of the accessory lacrimal glands of Wolfring is presented. Once appreciated, they are an easily recognized clinical entity.

METHODS

The 13 cases were verified histologically as arising from ductal epithelium. Biochemical analyses for serum and cyst fluid concentrations of IgA, IgG, and IgM were performed on three of the cases. Histologic staining of the cyst wall using monoclonal antibodies to immunoglobulins was performed on one case.

FINDINGS

All patients had evidence of extensive trachomatous scarring. High levels of IgA were found in the cyst fluid, consistent with an active secretory mechanism. Monoclonal antibody staining suggested a significant role for paraductal IgA-secreting plasma cells.

CONCLUSION

The formation of a ductal cyst appears to require two successive, inter-related events. The first is an ongoing active secretory process, and the second is an occlusion of the duct. The sequential occurrence of these two events is forwarded as the explanation of dacryops formation. Excision using a conjunctival approach is recommended. A small strip of tarsal border should be removed with the cyst to prevent cyst rupture. The excretory ducts of the Wolfring glands exit through this area.

Chlamydia keratoconjunctivitis determination of Chlamydia trachomatis specific secretory immunoglobulin A in tears by enzyme immunoassay

Determination of Chlamydia trachomatis specific antibodies in serum and tears, isolation of C. trachomatis in cell culture and C. trachomatis antigen detection by direct immunofluorescence test were evaluated for the laboratory diagnosis of Chlamydia trachomatis infection in 30 patients with chronic conjunctivitis. C. trachomatis specific secretory immunoglobulin A (s-IgA) was detected in the tears of all 8 patients with a positive result in culture and the direct immunofluorescence test. In 4 additional patients, the s-IgA assay of tears was also positive. A presumptive clinical diagnosis of Chlamydia conjunctivitis was correlated with the presence of s-IgA in tears. S-IgA was not detected in the serum of any of the patients, indicating that s-IgA is locally produced and not transudated from the serum. For the diagnosis of chronic Chlamydia conjunctivitis, we recommend the determination of s-IgA in tears in addition to a test for Chlamydia detection.

Antibodies in human tears during and after infection

The tear content of antibodies specific for various infectious agents has recently begun to be investigated. Important parameters of tear analysis with respect to antibody content are the method of tear collection and the laboratory techniques used to detect specific antibodies in the lacrimal fluid. Normal tears contain antibodies directed against both bacteria and viruses, and the antibody response in lacrimal fluid during immunization of animals and humans has been studied to some extent. This response has also been analyzed in humans during and after natural infection with certain viral and bacterial pathogens. It has become clear that local antibody synthesis takes place in the lacrimal gland, but at least some of these antibodies appear in tears because of lymphocyte sensitization in the common mucosal immune system. A certain degree of transudation of serum antibodies to tears is also often encountered, especially in severely inflamed eyes. Much of the data currently available needs to be confirmed, and more extensive studies need to be carried out for many pathogens. Potential benefits of such studies include development of new diagnostic techniques as well as a better understanding of when and how antibodies confer protection or may be potentially damaging.

Serum and tear immunoglobulins in bacterial, fungal and viral corneal ulcers

Serum and tear IgA, IgG and IgM levels were studied in patients with bacterial, fungal and viral corneal ulcers. In patients with viral corneal ulcers serum IgA and IgG levels were found to be significantly raised, while IgM concentration remained unaltered. In bacterial and mycotic ulcerations, serum IgA, IgG and IgM levels remained unaltered. All three immunoglobulins were found to be raised in tears of patients with viral corneal ulcers, while only IgA levels were found to be increased in bacterial and mycotic ulcerations.

Virus-specific IgA in serum, saliva, and tears of children with measles

Measles-specific IgA antibody titres were determined by radioimmunoassay (RIA) for serial serum, saliva and tear samples obtained from 21 children with measles infection, from onset of rash until up to 14 months later. Serum IgA titres rose rapidly after onset of illness and remained detectable throughout the follow-up period. Virus-specific salivary IgA titres peaked at 4 to 7 days after onset of rash and decreased thereafter. Measles-specific lacrimal fluid IgA antibodies remained elevated for long periods of time; however, secretory component-bearing measles-specific antibodies in tears became for the most part undetectable by 1 month after onset of rash. These data raise anew the question of whether some form of viral latency is associated with the presence of virus-specific IgA antibody, or whether such antibody is simply a reflection of immune memory.

Management and prevention of ocular viral and chlamydial infections

A majority of cases of preventable and/or curable ocular morbidity and blindness are caused by ocular infections. They may account for 70 to 90% of all ocular morbidity seen by family doctors, general practitioners, health centers, and local ophthalmologists in both developed and developing countries. Unfortunately, most health authorities and doctors, including ophthalmologists, consider these diseases to be of little or no importance because they are not fully aware of the high prevalence of these infections and the blinding sequelae which may occur following incorrect diagnosis and treatment. Also, they are not aware of the social and economic impact of these infections in the absence of proper management and implementation of preventive measures. In this review, we examine present knowledge of chlamydial and common viral ocular infections. We discuss the problems of diagnosis, management, and prevention and propose solutions relevant to developed and developing countries.

Secretory IgA against herpes simplex virus in cervical secretions

A recently developed method to recover proteins from cervical secretions was combined with methods to detect minute concentrations of herpes simplex virus (HSV) type specific antibodies to measure the concentrations of locally produced antibodies in women with genital infections. Forty nine women attending a sexually transmitted disease (STD) clinic were included. Cervical secretions were obtained by suction into a plastic catheter. Soluble proteins were recovered from the secretions by elution with hyperosmolar sodium chloride. A rabbit antibody to human secretory component, which was conjugated to horseradish peroxidase, was used to measure secretory IgA (S-IgA) that was HSV type specific. For comparison, HSV type specific IgG was measured in serum samples from the patients. Of the 49 women, 16 yielded detectable HSV type 2 (HSV 2) S-IgA in secretions. Twelve of them also reacted to the HSV type common antigen, but only five had HSV 2 IgG detectable in their serum. S-IgA against HSV was found in significantly more women with a clinical diagnosis of acute cervicitis than in others. This could be explained by a general increase in local antibody production and immunity triggered by previous contacts with HSV. It is concluded that local mucosal immunity to HSV 2 can be detected in women who do not have a specific humoral antibody response to the virus. For seroepidemiological studies of infection with HSV 2 this local immunity may be considered to be a factor that gives an underestimation of the true incidence of HSV 2 infection.

Mucosal antibody response to vaginal infection with herpes simplex virus in pre-vaccinated guinea-pigs

The mucosal antibody response, in female guinea-pigs vaccinated with the Skinner herpes simplex virus vaccine, has been investigated. The HSV-specific secretory IgA response was assessed using the cross-reactivity of an antiserum raised against human secretory component. Animals vaccinated subcutaneously at a distant site were shown to respond to subsequent infection with HSV by the production of HSV-specific vaginal IgG and secretory IgA. No vaginal HSV-specific antibodies were found in infected, non-vaccinated animals.

Herpes simplex-specific IgG subclass response in herpetic keratitis

The measurement of the local IgG response in ocular Herpes simplex virus infection presents particular problems due to the difficulty in obtaining sufficient tear samples and the possible transudation of IgG from the serum to the inflamed eye. Using specific monoclonal antibodies to Human IgG subclasses in an enzyme-linked immunoabsorbant assay (ELISA) the local IgG antibody response in Herpes simplex keratitis was analysed. All serum samples from patients and controls contained quantifiable levels of HSV specific IgG1 and IgG4 antibody. Comparison of serum antibody levels with tear levels for patients showed that HSV specific IgG1 serum concentrations were 16.1 fold or more higher than in tears, whereas IgG4 concentrations were only 6.5 fold higher in serum than in tears. This difference was not apparent in the control group. Radioimmunoprecipitation assay of 35S-methionine labelled HSV antigens revealed only minor differences in the protein profiles produced by immunoprecipitation using serum or tear antibody. These results suggest a role for IgG4 antibodies in mucosal immunity in the eye as has been suggested for the mucosal surface of the lung.