Use of saliva for early dengue diagnosis

Next-generation diagnostic test for dengue virus detection using an ultrafast plasmonic colorimetric RT-PCR strategy

The current global COVID-19 pandemic once again highlighted the urgent need for a simple, cost-effective, and sensitive diagnostic platform that can be rapidly developed for distribution and easy access in resource-limited areas. Here, we present a simple and low-cost plasmonic photothermal (PPT)-reverse transcription-colorimetric polymerase chain reaction (RTcPCR) for molecular diagnosis of dengue virus (DENV) infection. The assay can be completed within 54 min with an estimated detection limit of 1.6 copies/μL of viral nucleic acid. The analytical sensitivity and specificity of PPT-RTcPCR were comparable to that of the reference RT-qPCR assay. Moreover, the clinical performance of PPT-RTcPCR was evaluated and validated using 158 plasma samples collected from patients suspected of dengue infection. The results showed a diagnostic agreement of 97.5% compared to the reference RT-qPCR and demonstrated a clinical sensitivity and specificity of 97.0% and 100%, respectively. The simplicity and reliability of our PPT-RTcPCR strategy suggest it can provide a foundation for developing a field-deployable diagnostic assay for dengue and other infectious diseases.

Immunoglobulin M seroneutralization for improved confirmation of Japanese encephalitis virus infection in a flavivirus-endemic area

BACKGROUND

The mainstay of diagnostic confirmation of acute Japanese encephalitis (JE) involves detection of anti-JE virus (JEV) immunoglobulin M (IgM) by enzyme-linked immunosorbent assay (ELISA). Limitations in the specificity of this test are increasingly apparent with the introduction of JEV vaccinations and the endemicity of other cross-reactive flaviviruses. Virus neutralization testing (VNT) is considered the gold standard, but it is challenging to implement and interpret. We performed a pilot study to assess IgG depletion prior to VNT for detection of anti-JEV IgM neutralizing antibodies (IgM-VNT) as compared with standard VNT.

METHODS

We evaluated IgM-VNT in paired sera from anti-JEV IgM ELISA-positive patients (JE n=35) and negative controls of healthy flavivirus-naïve (n=10) as well as confirmed dengue (n=12) and Zika virus (n=4) patient sera. IgM-VNT was subsequently performed on single sera from additional JE patients (n=76).

RESULTS

Anti-JEV IgG was detectable in admission serum of 58% of JE patients. The positive, negative and overall percentage agreement of IgM-VNT as compared with standard VNT was 100%. A total of 12/14 (86%) patient samples were unclassified by VNT and, with sufficient sample available for IgG depletion and IgG ELISA confirming depletion, were classified by IgM-VNT. IgM-VNT enabled JE case classification in 72/76 (95%) patients for whom only a single sample was available.

CONCLUSIONS

The novel approach has been readily adapted for high-throughput testing of single patient samples and it holds promise for incorporation into algorithms for use in reference centres.

Direct Viral RNA Detection of SARS-CoV-2 and DENV in Inactivated Samples by Real-Time RT-qPCR: Implications for Diagnosis in Resource Limited Settings with Flavivirus Co-Circulation

The RT-qPCR method remains the gold standard and first-line diagnostic method for the detection of SARS-CoV-2 and flaviviruses, especially in the early stage of viral infection. Rapid and accurate viral detection is a starting point in the containment of the COVID-19 pandemic and flavivirus outbreaks. However, the shortage of diagnostic reagents and supplies, especially in resource-limited countries that experience co-circulation of SARS-CoV-2 and flaviviruses, are limitations that may result in lesser availability of RT-qPCR-based diagnostic tests. In this study, the utility of RNA-free extraction methods was assessed for the direct detection of SARS-CoV-2 and DENV-2 in heat-inactivated or chemical-inactivated samples. The findings demonstrate that direct real-time RT-qPCR is a feasible option in comparison to conventional real-time RT-qPCR based on viral genome extraction-based methods. The utility of heat-inactivation and direct real-time RT-qPCR for SARS-CoV-2, DENV-2 viral RNA detection was demonstrated by using clinical samples of SARS-CoV-2 and DENV-2 and spiked cell culture samples of SARS-CoV-2 and DENV-2. This study provides a simple alternative workflow for flavivirus and SARS-CoV-2 detection that includes heat inactivation and viral RNA extraction-free protocols, with aims to reduce the risk of exposure during processing of SARS-CoV-2 biological specimens and to overcome the supply-chain bottleneck, particularly in resource limited settings with flavivirus co-circulation.

Non-Invasive Dengue Diagnostics-The Use of Saliva and Urine for Different Stages of the Illness

Dengue diagnosis is largely dependent on clinical symptoms and routinely confirmed with laboratory detection of dengue virus in patient serum samples collected via phlebotomy. This presents a challenge to patients not amenable to venipuncture. Non-invasive methods of dengue diagnosis have the potential to enhance the current dengue detection algorithm. In this study, samples from dengue infected patients were collected between January 2012 until September 2012 and September 2013 until December 2013 in two different setups. Panel A samples (blood, urine, and saliva) were collected daily when the 39 patients were hospitalised and during their follow-up visits while Panel B samples (saliva) were collected from 23 patients during the acute stage of dengue. Using DENV PCR on Panel A, from day 2 to day 4 post fever onset, serum showed the best overall positivity followed by saliva and urine (100%/82.1%/67.9%). From day 5 until day 10 post fever onset, serum and urine had similar positivity (67.4%/61.2%), followed by saliva (51.3%). Beyond day 10 post fever onset, DENV was undetectable in sera, but urine and saliva showed 56.8% and 28.6% positivity, respectively. DENV in urine was detectable up until 32 days post fever. Panel B results showed overall sensitivity of 32.4%/36% (RNA/NS1) for DENV detection in saliva. Our results suggest that the urine-based detection method is useful especially for late dengue detection, where DENV is undetected in sera but still detectable in urine. This provides a potential tool for the physician to pick up new cases in an area where there is ongoing dengue transmission and subsequently prompt for intensified vector control activities.

Salivary Antibodies against Multiple Environmental Pathogens Found in Individuals Recreating at an Iowa Beach

Detecting environmental exposures and mitigating their impacts are growing global public health challenges. Antibody tests show great promise and have emerged as fundamental tools for large-scale exposure studies. Here, we apply, demonstrate and validate the utility of a salivary antibody multiplex immunoassay in measuring antibody prevalence and immunoconversions to six pathogens commonly found in the environment. The study aimed to assess waterborne infections in consenting beachgoers recreating at an Iowa riverine beach by measuring immunoglobulin G (IgG) antibodies against select pathogens in serially collected saliva samples. Results showed that nearly 80% of beachgoers had prior exposures to at least one of the targeted pathogens at the beginning of the study. Most of these exposures were to norovirus GI.1 (59.41%), norovirus GII.4 (58.79%) and Toxoplasma gondii (22.80%) and over half (56.28%) of beachgoers had evidence of previous exposure to multiple pathogens. Of individuals who returned samples for each collection period, 6.11% immunoconverted to one or more pathogens, largely to noroviruses (GI.1: 3.82% and GII.4: 2.29%) and T. gondii (1.53%). Outcomes of this effort illustrate that the multiplex immunoassay presented here serves as an effective tool for evaluating health risks by providing valuable information on the occurrence of known and emerging pathogens in population surveillance studies.

In Nasal Mucosal Secretions, Distinct IFN and IgA Responses Are Found in Severe and Mild SARS-CoV-2 Infection

Likely as in other viral respiratory diseases, SARS-CoV-2 elicit a local immune response, which includes production and releasing of both cytokines and secretory immunoglobulin (SIgA). Therefore, in this study, we investigated the levels of specific-SIgA for SARS-CoV-2 and cytokines in the airways mucosa 37 patients who were suspected of COVID-19. According to the RT-PCR results, the patients were separated into three groups: negative for COVID-19 and other viruses (NEGS, n = 5); negative for COVID-19 but positive for the presence of other viruses (OTHERS, n = 5); and the positive for COVID-19 (COVID-19, n = 27). Higher specific-SIgA for SARS-CoV-2, IFN-β, and IFN-γ were found in the COVID-19 group than in the other groups. Increased IL-12p70 levels were observed in OTHERS group as compared to COVID-19 group. When the COVID-19 group was sub stratified according to the illness severity, significant differences and correlations were found for the same parameters described above comparing severe COVID-19 to the mild COVID-19 group and other non-COVID-19 groups. For the first time, significant differences are shown in the airway's mucosa immune responses in different groups of patients with or without respiratory SARS-CoV-2 infection.

A need to raise the bar - A systematic review of temporal trends in diagnostics for Japanese encephalitis virus infection, and perspectives for future research

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Japanese encephalitis virus (JEV) remains a leading cause of neurological infection in Asia.

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A systematic review identified 20,212 published human cases of laboratory-confirmed JEV infections from 205 studies.

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15,167 (75%) of cases were confirmed with the lowest confidence diagnostic test, i.e., level 3 or 4, or level 4.

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Only 109 (53%) of the studies reported contemporaneous testing for dengue-specific antibodies.

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A fundamental pre-requisite for the control of JE is lacking — that of a simple and specific diagnostic procedure that can be adapted for point-of-care tests and readily used throughout JE endemic regions of the world.

Objective

Japanese encephalitis virus infection (JE) remains a leading cause of neurological disease in Asia, mainly involving individuals living in remote areas with limited access to treatment centers and diagnostic facilities. Laboratory confirmation is fundamental for the justification and implementation of vaccination programs. We reviewed the literature on historical developments and current diagnostic capability worldwide, to identify knowledge gaps and instill urgency to address them.

Methods

Searches were performed in Web of Science and PubMed using the term 'Japanese encephalitis' up to 13th October 2019. Studies reporting laboratory-confirmed symptomatic JE cases in humans were included, and data on details of diagnostic tests were extracted. A JE case was classified according to confirmatory levels (Fischer et al., 2008; Campbell et al., 2011; Pearce et al., 2018; Heffelfinger et al., 2017), where level 1 represented the highest level of confidence.

Findings

20,212 published JE cases were identified from 205 studies. 15,167 (75%) of these positive cases were confirmed with the lowest-confidence diagnostic tests (level 3 or 4, or level 4). Only 109 (53%) of the studies reported contemporaneous testing for dengue-specific antibodies.

Conclusion

A fundamental pre-requisite for the control of JEV is lacking — that of a simple and specific diagnostic procedure that can be adapted for point-of-care tests and readily used throughout JE-endemic regions of the world.

Find the right sample: A study on the versatility of saliva and urine samples for the diagnosis of emerging viruses

BACKGROUND

The emergence of different viral infections during the last decades like dengue, West Nile, SARS, chikungunya, MERS-CoV, Ebola, Zika and Yellow Fever raised some questions on quickness and reliability of laboratory diagnostic tests for verification of suspected cases. Since sampling of blood requires medically trained personal and comprises some risks for the patient as well as for the health care personal, the sampling by non-invasive methods (e.g. saliva and/ or urine) might be a very valuable alternative for investigating a diseased patient.

MAIN BODY

To analyse the usefulness of alternative non-invasive samples for the diagnosis of emerging infectious viral diseases, a literature search was performed on PubMed for alternative sampling for these viral infections. In total, 711 papers of potential relevance were found, of which we have included 128 in this review.

CONCLUSIONS

Considering the experience using non-invasive sampling for the diagnostic of emerging viral diseases, it seems important to perform an investigation using alternative samples for routine diagnostics. Moreover, during an outbreak situation, evaluation of appropriate sampling and further processing for laboratory analysis on various diagnostic platforms are very crucial. This will help to achieve optimal diagnostic results for a good and reliable case identification.

DNA Switch: Toehold-Mediated DNA Isothermal Amplification for Dengue Serotyping

The inherent ability of nucleic acids to recognize a complementary pair has gained wide popularity in DNA sensor applications. DNA molecules can be produced in bulk and easily incorporated with various nanomaterials for sensing applications. More complex designs and sophisticated DNA sensors have been reported over the years to allow DNA detection in a faster, cheaper, and more convenient manner. Here, we report a DNA sensor designed to function like a switch to turn “on” silver nanocluster (AgNC) generation in the presence of a specific DNA target. By defining the probe region sequence, we are able to tune the color of the AgNC generated in direct relation to the different targets. As a proof of concept, we used dengue RNA-dependent RNA polymerase conserved sequences from all four serotypes as targets. This method was able to distinguish each dengue serotype by generating the serotype-respective AgNCs. The DNA switch was also able to identify and amplify the correct target in a mixture of targets with good specificity. This strategy has a detection limit of between 1.5 and 2.0 µM depending on the sequence of AgNC. The DNA switch approach provides an attractive alternative for single-target or multiplex DNA detection.

First detection of dengue virus in the saliva of immunocompetent murine model

The lack of an experimental animal model for the study of dengue pathogenesis is a limiting factor for the development of vaccines and drugs. In previous studies, our group demonstrated the susceptibility of BALB/c mice to infection by dengue virus (DENV) 1 and 2, and the virus was successfully isolated in several organs. In this study, BALB/c mice were experimentally infected intravenously with DENV-4, and samples of their saliva were collected. Viral RNA extracted from the saliva samples was subjected to qRT-PCR, with a detection limit of 0.002 PFU/mL. The presence of DENV-4 viral RNA was detected in the saliva of two mice, presenting viral titers of 109 RNA/mL. The detection of DENV RNA via saliva sampling is not a common practice in dengue diagnosis, due to the lower detection rates in human patients. However, the results observed in this study seem to indicate that, as in humans, detection rates of DENV RNA in mouse saliva are also low, correlating the infection in both cases. This study reports the first DENV detection in the saliva of BALB/c immunocompetent mice experimentally infected with non-neuroadapted DENV-4.

Viral and Antibody Kinetics, and Mosquito Infectivity of an Imported Case of Zika Fever Due to Asian Genotype (American Strain) in Singapore

We report a case of a Singaporean who acquired Zika virus (ZIKV) during a visit to Cuba. The infection was confirmed using molecular and serological methods. This report highlights potential drawbacks of using IgG serology for diagnosis of flavivirus infections in endemic regions. The low viremia detected during the early phase of this case resulted in low mosquito infectivity rates, suggesting the possibility of ZIKV transmission prior to clinical onset. The report also emphasizes the challenges of public health interventions for Zika fever and the importance of sustaining a low vector population to reduce the risk of arbovirus transmission in vulnerable regions.

Marker of coxsackievirus-B4 infection in saliva of patients with type 1 diabetes

BACKGROUND

Coxsackieviruses B (CV-B) are enteroviruses that have been reported to play a role in the pathogenesis of type 1 diabetes. Enteroviral RNA was detected in the gut mucosa of patients. The mucosal immunity is an interconnected network; therefore, the response to enteroviruses possibly present in the gastrointestinal mucosa can be reflected by specific antibodies in the saliva. In the present study, the anti-CV-B neutralizing activity of saliva samples from patients with type 1 diabetes was investigated.

METHODS

Saliva samples were collected from patients and controls of 3 countries, and plasma was obtained from some of them. The anti-CV-B activity of clinical samples was determined by neutralization of the cytopathic effect induced by challenging viruses in vitro and expressed as titre value.

RESULTS

Overall prevalence and levels of anti-CV-B4 activity of saliva were higher in patients (n = 181) than in controls (n = 135; P = .0002; titre values ≥ 16: odds ratio = 4.22 95% CI: 1.90-9.38 P = .0002). It has been shown that IgA1 played a role in this activity. There was no correlation between the saliva and the plasma anti-CV-B4 neutralizing activity. The neutralizing activity of saliva against CV-B1, CV-B2, CV-B3, and CV-B5 existed rarely, if at all. Increased levels of anti-CV-B4 activity were observed all along a 4 year follow-up period in patients but not in matched controls (P = .01).

CONCLUSION

There is an anti-CV-B4 activity in saliva of patients with type 1 diabetes that may be a useful marker to study the role of CV-B in the pathogenesis of the disease.

PCA-MLP SVM distinction of salivary Raman spectra of dengue fever infection

Dengue fever (DF) is a disease of major concern caused by flavivirus infection. Delayed diagnosis leads to severe stages, which could be deadly. Of recent, non-structural protein (NS1) has been acknowledged as a biomarker, alternative to immunoglobulins for early detection of dengue in blood. Further, non-invasive detection of NS1 in saliva makes the approach more appealing. However, since its concentration in saliva is less than blood, a sensitive and specific technique, Surface Enhanced Raman Spectroscopy (SERS), is employed. Our work here intends to define an optimal PCA-SVM (Principal Component Analysis-Support Vector Machine) with Multilayer Layer Perceptron (MLP) kernel model to distinct between positive and negative NS1 infected samples from salivary SERS spectra, which, to the best of our knowledge, has never been explored. Salivary samples of DF positive and negative subjects were collected, pre-processed and analyzed. PCA and SVM classifier were then used to differentiate the SERS analyzed spectra. Since performance of the model depends on the PCA criterion and MLP parameters, both are examined in tandem. Its performance is also compared to our previous works on simulated NS1 salivary samples. It is found that the best PCA-SVM (MLP) model can be defined by 95 PCs from CPV criterion with P1 and P2 values of 0.01 and -0.2 respectively. A classification performance of [76.88%, 85.92%, 67.83%] is achieved.

Saliva and viral infections

Over the last 10 years there have been only a handful of publications dealing with the oral virome, which is in contrast to the oral microbiome, an area that has seen considerable interest. Here, we survey viral infections in general and then focus on those viruses that are found in and/or are transmitted via the oral cavity; norovirus, rabies, human papillomavirus, Epstein‐Barr virus, herpes simplex viruses, hepatitis C virus, and HIV. Increasingly, viral infections have been diagnosed using an oral sample (e.g. saliva mucosal transudate or an oral swab) instead of blood or urine. The results of two studies using a rapid and semi‐quantitative lateral flow assay format demonstrating the correlation of HIV anti‐IgG/sIgA detection with saliva and serum samples are presented. When immediate detection of infection is important, point‐of‐care devices that obtain a non‐invasive sample from the oral cavity can be used to provide a first line diagnosis to assist in determining appropriate counselling and therapeutic path for an increasing number of diseases.

Immunoprevalence to Six Waterborne Pathogens in Beachgoers at Boquerón Beach, Puerto Rico: Application of a Microsphere-Based Salivary Antibody Multiplex Immunoassay

Waterborne infectious diseases are a major public health concern worldwide. Few methods have been established that are capable of measuring human exposure to multiple waterborne pathogens simultaneously using non-invasive samples such as saliva. Most current methods measure exposure to only one pathogen at a time, require large volumes of individual samples collected using invasive procedures, and are very labor intensive. In this article, we applied a multiplex bead-based immunoassay capable of measuring IgG antibody responses to six waterborne pathogens simultaneously in human saliva to estimate immunoprevalence in beachgoers at Boquerón Beach, Puerto Rico. Further, we present approaches for determining cutoff points to assess immunoprevalence to the pathogens in the assay. For the six pathogens studied, our results show that IgG antibodies against antigens from noroviruses GI.I and GII.4 were more prevalent (60 and 51.6%, respectively) than Helicobacter pylori (21.4%), hepatitis A virus (20.2%), Campylobacter jejuni (8.7%), and Toxoplasma gondii (8%) in the saliva of the study participants. The salivary antibody multiplex immunoassay can be used to examine immunoprevalence of specific pathogens in human populations.

Oral Biofluid Biomarker Research: Current Status and Emerging Frontiers

Salivary diagnostics is a rapidly advancing field that offers clinicians and patients the potential of rapid, noninvasive diagnostics with excellent accuracy. In order for the complete realization of the potential of saliva, however, extensive profiling of constituents must be conducted and diagnostic biomarkers must be thoroughly validated. This article briefly overviews the process of conducting a study of salivary biomarkers in a patient cohort and highlights the studies that have been conducted on different classes of molecules in the saliva. Emerging frontiers in salivary diagnostics research that may significantly advance the field will also be highlighted.

Developing a Salivary Antibody Multiplex Immunoassay to Measure Human Exposure to Environmental Pathogens

The etiology and impacts of human exposure to environmental pathogens are of major concern worldwide and, thus, the ability to assess exposure and infections using cost effective, high-throughput approaches would be indispensable. This manuscript describes the development and analysis of a bead-based multiplex immunoassay capable of measuring the presence of antibodies in human saliva to multiple pathogens simultaneously. Saliva is particularly attractive in this application because it is noninvasive, cheaper and easier to collect than serum. Antigens from environmental pathogens were coupled to carboxylated microspheres (beads) and used to measure antibodies in very small volumes of human saliva samples using a bead-based, solution-phase assay. Beads were coupled with antigens from Campylobacter jejuni, Helicobacter pylori, Toxoplasma gondii, noroviruses (G I.1 and G II.4) and hepatitis A virus. To ensure that the antigens were sufficiently coupled to the beads, coupling was confirmed using species-specific, animal-derived primary capture antibodies, followed by incubation with biotinylated anti-species secondary detection antibodies and streptavidin-R-phycoerythrin reporter (SAPE). As a control to measure non-specific binding, one bead set was treated identically to the others except it was not coupled to any antigen. The antigen-coupled and control beads were then incubated with prospectively-collected human saliva samples, measured on a high throughput analyzer based on the principles of flow cytometry, and the presence of antibodies to each antigen was measured in Median Fluorescence Intensity units (MFI). This multiplex immunoassay has a number of advantages, including more data with less sample; reduced costs and labor; and the ability to customize the assay to many targets of interest. Results indicate that the salivary multiplex immunoassay may be capable of identifying previous exposures and infections, which can be especially useful in surveillance studies involving large human populations.

Evaluation of the performances of six commercial kits designed for dengue NS1 and anti-dengue IgM, IgG and IgA detection in urine and saliva clinical specimens

Background

Rapid diagnostic tests (RDTs) have been commercialized in order to help physicians in dengue diagnosis. Until recently, only blood samples were used for those tests but it has been shown in several studies that urine and saliva can also be employed for dengue diagnosis. RDTs for the detection of NS1 antigen and anti-dengue IgG, IgM and IgA in urine and saliva specimens have thus been developed by Standard Diagnostics. The aim of this study was to evaluate the performances these new commercial assays.

Methods

Two panels of clinical specimens were used: one for the evaluation of the NS1-detection devices and the second for the evaluation of the antibody-detection kits. Each panel consisted of urine and saliva specimens collected sequentially from 86 patients with a confirmed dengue infection. A total of 291 saliva and 440 urine samples were included in the NS1-evaluation panel and 530 saliva and 528 urine specimens constituted the antibody-evaluation panel. All samples were tested in parallel by in-house ELISAs and by the commercial RDTs.

Results

The RDTs demonstrated an overall sensitivity of 15.5 %/27.9 %/10.7 % for NS1/IgG/IgA detection in urine samples and 20.4 %/ 34.8 %/11 %/6.2 % for NS1/IgG/IgM/IgA detection in saliva samples. Compared to the in-house NS1 ELISA, the results obtained with the NS1 RDT demonstrated a good correlation with urine samples (kappa coefficient: 0.88) but not with saliva specimens (kappa coefficient: 0.28). RDTs designed for antibody detection in saliva and urine were extremely specific (100 %), but less sensitive than the in-house ELISAs (i.e., reduction of the overall sensitivity by 12.2 % for the RDT designed for IgG detection in urine and by 23.7 % for the RDT detecting anti-DENV IgM in saliva). IgM were not detected in urine, either by RDT or ELISA.

Conclusions

Although the RDTs evaluated here offer an apparently attractive approach for dengue diagnosis, this study suggests that these new commercial kits would require further improvement to increase the sensitivity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1551-x) contains supplementary material, which is available to authorized users.

Salivary Markers for Periodontal and General Diseases

The determination of biomarkers in saliva is becoming an important part of laboratory diagnostics and the prediction of not only periodontal, but also other tissue and organ diseases. Biomarkers in saliva (e.g., enzymes, protein markers, or oxidative stress markers) can be used for activity determination and for periodontal disease prognosis. Saliva also contains many markers which can predict the risk of certain diseases (e.g., diabetes mellitus, cardiovascular, oncology, endocrinology, and psychiatric diseases). The study of salivary components proteomics clearly shows the relationship of periodontal diseases and diseases of distant systems, organs, or tissues.

Evaluation of Salivary Secretory Immunoglobulin A Levels in Diabetic Patients and Association with Oral and Dental Manifestations

OBJECTIVES

Oral and dental manifestations in diabetic patients can arise due to numerous factors, including elevated salivary secretory immunoglobulin A (s-IgA) levels. This study aimed to evaluate s-IgA concentrations in patients with type 2 diabetes mellitus (T2DM) and to investigate the association between s-IgA levels and oral and dental manifestations of T2DM.

METHODS

This cross-sectional descriptive study was carried out between October 2011 and September 2012 in Kerman, Iran, and included 260 subjects (128 patients with T2DM and 132 healthy controls). Unstimulated salivary samples were collected from all subjects and s-IgA levels were determined using the immunoturbidimetric method. The oral cavities and teeth of T2DM patients were evaluated for oral and dental manifestations.

RESULTS

Both diabetic and control subjects with higher concentrations of s-IgA had significantly higher numbers of decayed, missing or filled teeth (DMFT) and periodontal index (PDI) scores (P <0.050). s-IgA levels were significantly higher in subjects with oral candidiasis (P <0.050). Among diabetic patients, significantly higher s-IgA levels were concomitant with xerostomia and denture stomatitis (P ≤0.050). There were no significant differences between s-IgA concentrations and other oral or dental manifestations in either group.

CONCLUSION

Individuals with a greater number of DMFT, a higher PDI score and oral candidiasis had significantly higher s-IgA levels. s-IgA levels were not significantly higher among diabetic patients in comparison to the control group. However, significantly higher s-IgA levels occurred with xerostomia and denture stomatitis in diabetic patients. In addition, s-IgA was significantly higher in patients with uncontrolled diabetes compared to those with controlled diabetes.

Diagnostic Options and Challenges for Dengue and Chikungunya Viruses

Dengue virus (DENV) and Chikungunya virus (CHIKV) are arboviruses that share the same Aedes mosquito vectors and thus overlap in their endemic areas. These two viruses also cause similar clinical presentations, especially in the initial stages of infection, with neither virus possessing any specific distinguishing clinical features. Because the outcomes and management strategies for these two viruses are vastly different, early and accurate diagnosis is imperative. Diagnosis is also important for surveillance, outbreak control, and research related to vaccine and drug development. Available diagnostic tests are aimed at detection of the virus, its antigenic components, or the host immune antibody response. In this review, we describe the recent progress and continued challenges related to the diagnosis of DENV and CHIKV infections.

Value of Routine Dengue Diagnostic Tests in Urine and Saliva Specimens

Background

Dengue laboratory diagnosis is essentially based on detection of the virus, its components or antibodies directed against the virus in blood samples. Blood, however, may be difficult to draw in some patients, especially in children, and sampling during outbreak investigations or epidemiological studies may face logistical challenges or limited compliance to invasive procedures from subjects. The aim of this study was to assess the possibility of using saliva and urine samples instead of blood for dengue diagnosis.

Methodology/Principal Findings

Serial plasma, urine and saliva samples were collected at several time-points between the day of admission to hospital until three months after the onset of fever in children with confirmed dengue disease. Quantitative RT-PCR, NS1 antigen capture and ELISA serology for anti-DENV antibody (IgG, IgM and IgA) detection were performed in parallel on the three body fluids. RT-PCR and NS1 tests demonstrated an overall sensitivity of 85.4%/63.4%, 41.6%/14.5% and 39%/28.3%, in plasma, urine and saliva specimens, respectively. When urine and saliva samples were collected at the same time-points and tested concurrently, the diagnostic sensitivity of RNA and NS1 detection assays was 69.1% and 34.4%, respectively. IgG/IgA detection assays had an overall sensitivity of 54.4%/37.4%, 38.5%/26.8% and 52.9%/28.6% in plasma, urine and saliva specimens, respectively. IgM were detected in 38.1% and 36% of the plasma and saliva samples but never in urine.

Conclusions

Although the performances of the different diagnostic methods were not as good in saliva and urine as in plasma specimens, the results obtained by qRT-PCR and by anti-DENV antibody ELISA could well justify the use of these two body fluids to detect dengue infection in situations when the collection of blood specimens is not possible.

Dengue is the most important arthropod-borne disease affecting humans and represents a huge public health burden in affected countries. Symptoms are often non-specific hence the need for an early, sensitive and specific diagnosis of dengue for appropriate management as well as for early epidemic detection. Currently, almost all laboratory diagnostic methods require a blood specimen that may be sometimes be difficult or inconvenient to obtain. In this study, we assessed the possibility to use saliva and urine samples as alternatives to blood specimens in dengue diagnosis. We demonstrated that the performances of the different diagnostic methods (RT-PCR, NS1 antigen detection and anti-DENV IgM/IgG/IgA ELISAs) were in general not as good in saliva and urine as in plasma, but that the use of these body fluids obtained by non-invasive methods could be of value in certain circumstances such as outbreak investigations or in young children (once they are old enough to comply to instructions), in addition to the situations when blood cannot be easily collected (e.g., lack of phlebotomist, refusal of the procedure, etc.).

A meta-analysis of the diagnostic accuracy of dengue virus-specific IgA antibody-based tests for detection of dengue infection

Immunoglobulin A (IgA)-based tests have been evaluated in different studies for their utility in diagnosing dengue infections. In most of the studies, the results were inconclusive because of a small sample size. Hence, a meta-analysis involving nine studies with 2096 samples was performed to assess the diagnostic accuracy of IgA-based tests in diagnosing dengue infections. The analysis was conducted using Meta-Disc software. The results revealed that IgA-based tests had an overall sensitivity, specificity, diagnostic odds ratio, and positive and negative likelihood ratios of 73·9%, 95·2%, 66·7, 22·0 and 0·25, respectively. Significant heterogeneity was observed between the studies. The type of test, infection status and day of sample collection influenced the diagnostic accuracy. The IgA-based diagnostic tests showed a greater accuracy when the samples were collected 4 days after onset of symptoms and for secondary infections. The results suggested that IgA-based tests had a moderate level of accuracy and are diagnostic of the disease. However, negative results cannot be used alone for dengue diagnosis. More prospective studies comparing the diagnostic accuracy of combinations of antigen-based tests with either IgA or IgM are needed and might be useful for suggesting the best strategy for dengue diagnosis.

Salivary gland disorders: A comprehensive review

Salivary glands are complex in nature. They could be either tubulo acinar, merocrine or exocrine glands secreting mainly saliva. Salivary gland is one of the main soft tissue structures in the maxillofacial area. Saliva is a clear, slightly acidic muco serous fluid that coats the teeth, mucosa and thereby helps to create and maintain a healthy environment in the oral cavity. Salivary glands may be affected by a number of diseases: local and systemic and the prevalence of salivary gland diseases depend on various etiological factors. The glands may be infected by viral, bacterial, rarely fungal or its ductal obstruction which may cause painful swelling or obstruction, affecting their functions. The salivary gland may also be affected by a various benign and malignant tumours. This review article briefly describes about the various salivary gland disorders, diagnostic techniques and their management including the recent advances and the future perspective.

A stacking flow immunoassay for the detection of dengue-specific immunoglobulins in salivary fluid

Paper-based immunoassays, usually in the form of lateral flow tests, are currently the standard platform for home diagnostics. However, conventional lateral tests are often complicated by severe non-specific adsorption of detector particles when applied to test samples containing salivary fluid. It is believed that a high concentration of proteinaceous substances in salivary fluid causes particle aggregation and adhesion. In this study, we developed a stacking flow platform for single-step detection of a target antibody in salivary fluid. Stacking flow circumvents the need for separate sample pre-treatments, such as filtration or centrifugation, which are often required prior to testing saliva samples using paper-based immunoassays. This is achieved by guiding the samples and reagents to the test strip through different paths. By doing so, salivary substances that interfere with the particle-based sensing system are removed before they come into contact with the detection reagents, which greatly reduces the background. In addition, the stacking flow configuration enables uniform flow with a unique flow regulator, which leads to even test lines with good quantification capability, enabling the detection of ~20 ng mL(-1) α-fetoprotein in the serum. We have successfully applied the stacking flow device to detect dengue-specific immunoglobulins that are present in salivary fluid.

Use of IgG in oral fluid to monitor infants with suspected congenital toxoplasmosis

Infants born to mothers who seroconverted for toxoplasmosis during pregnancy are at risk of sequelae. In the case of a negative work-up at birth, congenital infection can be ruled out only by monitoring the disappearance of maternal immunoglobulin G (IgG) transmitted through the placenta, which can be achieved by regular blood sampling during the first year. To alleviate the discomfort of this follow-up, we developed an indirect enzyme-linked immunosorbent assay to detect specific IgG diffusing passively from the blood through the gingival epithelium by collecting oral fluid on microsponges. To assess the feasibility of the test, 212 patients were first enrolled. Levels of specific IgG in oral fluid were significantly higher in seropositive (n = 195) than in seronegative (n = 17) patients (mean optical densities, 1.145 ± 0.99 versus 0.092 ± 0.127; P < 0.0001). In a population of 93 patients <15 months of age born to mothers who displayed toxoplasmic infection during pregnancy, 70 were free of congenital infection and were followed up until their serology turned negative, and 23 were congenitally infected. The same patterns of IgG were observed in the oral fluid and sera in each group. Using a cutoff of 0.04 (optical density value), the sensitivity and specificity of the test were 67.9% and 80.3%, respectively, and the probability of not having a congenital infection when the test on oral fluid was negative was 99%. Although the performance of the test needs to be improved, oral fluid sampling appears to be a promising tool for monitoring infants with suspected congenital toxoplasmosis.

Detection of total and PRRSV-specific antibodies in oral fluids collected with different rope types from PRRSV-vaccinated and experimentally infected pigs

BACKGROUND

Oral fluid collected by means of ropes has the potential to replace serum for monitoring and surveillance of important swine pathogens. Until now, the most commonly used method to collect oral fluid is by hanging a cotton rope in a pen. However, concerns about the influence of rope material on subsequent immunological assays have been raised. In this study, we evaluated six different rope materials for the collection of oral fluid and the subsequent detection of total and PRRSV-specific antibodies of different isotypes in oral fluid collected from PRRSV-vaccinated and infected pigs.

RESULTS

An initial experiment showed that IgA is the predominant antibody isotype in porcine saliva. Moreover, it was found that synthetic ropes may yield higher amounts of IgA, whereas all rope types seemed to be equally suitable for IgG collection. Although IgA is the predominant antibody isotype in porcine oral fluid, the PRRSV-specific IgA-based IPMA and ELISA tests were clearly not ideal for sensitive detection of PRRSV-specific IgA antibodies. In contrast, PRRSV-specific IgG in oral fluids was readily detected in PRRSV-specific IgG-based IPMA and ELISA tests, indicating that IgG is a more reliable isotype for monitoring PRRSV-specific antibody immunity in vaccinated/infected animals via oral fluids with the currently available tests.

CONCLUSIONS

Since PRRSV-specific IgG detection seems more reliable than PRRSV-specific IgA detection for monitoring PRRSV-specific antibody immunity via oral fluids, and since all rope types yield equal amounts of IgG, it seems that the currently used cotton ropes are an appropriate choice for sample collection in PRRSV monitoring.

Salivary biomarkers: toward future clinical and diagnostic utilities

The pursuit of timely, cost-effective, accurate, and noninvasive diagnostic methodologies is an endeavor of urgency among clinicians and scientists alike. Detecting pathologies at their earliest stages can significantly affect patient discomfort, prognosis, therapeutic intervention, survival rates, and recurrence. Diagnosis and monitoring often require painful invasive procedures such as biopsies and repeated blood draws, adding undue stress to an already unpleasant experience. The discovery of saliva-based microbial, immunologic, and molecular biomarkers offers unique opportunities to bypass these measures by utilizing oral fluids to evaluate the condition of both healthy and diseased individuals. Here we discuss saliva and its significance as a source of indicators for local, systemic, and infectious disorders. We highlight contemporary innovations and explore recent discoveries that deem saliva a mediator of the body's physiological condition. Additionally, we examine the current state of salivary diagnostics and its associated technologies, future aspirations, and potential as the preferred route of disease detection, monitoring, and prognosis.

Diagnostic efficacy of saliva for dengue - a reality in near future? A piloting initiative

BACKGROUND

Dengue, a mosquito-transmitted viral infection presents variable symptoms, including death. Due to their increasing incidences, early detection and improved diagnoses of severe cases are of prime importance. Currently, viral antigens and antibodies are detected by traditional serological tests. However, the introduction of oral fluid as an alternative, has led to many researches. Hence, this prompted us to carry out a pilot study to evaluate the diagnostic efficacy of saliva in detecting dengue antibody by using Enzyme Linked Immunosorbent Assay (ELISA).

AIM AND OBJECTIVES

To evaluate the presence of Dengue antibody in saliva and its sensitivity and specificity through ELISA.

METHODOLOGY AND RESULTS

Twenty seropositive patients and twenty seronegative patients of Dengue were considered individually. Saliva samples collected from these patients were subjected to ELISA test for detection of Dengue antibody. A sensitivity of 100% and a specificity of 100% were obtained for making a diagnosis of Dengue infection.

CONCLUSION

Many studies have been conducted by utilizing saliva as a diagnostic tool, especially in western population. Its advantages over venipuncture are many, especially as it is less invasive, safe, less expensive and as it allows large numbers of samples to be collected easily for screening and epidemiological purposes. In a developing tropical country like India, such a diagnostic tool has to be encouraged. Further research necessitates the implementation of saliva as a diagnostic tool.

Dengue: Moving from Current Standard of Care to State-of-the-Art Treatment

Treatment of dengue remains supportive in the absence of targeted antiviral therapy or approved vaccines. Responsive fluid management is key to preventing progression to shock or other severe manifestations. The dynamic natural history of dengue infection and its influence on hemodynamic homeostasis needs to be carefully considered in the planning of individualized therapy. Though largely self-limiting, the sheer burden of dengue disease on the global population will result in atypical manifestations especially in children, older adults, and comorbid patients. Management of these has not yet been systematized. The failure of recent randomized controlled trials to show utility for antiviral and immunomodulatory agents in dengue is disappointing. Vaccine candidates hold promise, but growing outbreaks require more robust, evidence-based management guidelines to inform clinicians, especially in novel epidemic situations.

Detecting viruses by using salivary diagnostics

BACKGROUND

Diagnostics that involve the use of oral fluids have become increasingly available commercially in recent years and are of particular interest because of their relative ease of use, low cost and noninvasive collection of oral fluid for testing.

TYPES OF STUDIES REVIEWED

The authors discuss the use of salivary diagnostics for virus detection with an emphasis on rapid detection of infection by using point-of-care devices. In particular, they review salivary diagnostics for human immunodeficiency virus, hepatitis C virus and human papillomavirus. Oral mucosal transudate contains secretory immunoglobulin (Ig) A, as well as IgM and IgG, which makes it a good source for immunodiagnostic-based devices.

CLINICAL IMPLICATIONS

Because patients often visit a dentist more regularly than they do a physician, there is increased discussion in the dental community regarding the need for practitioners to be aware of salivary diagnostics and to be willing and able to administer these tests to their patients.

Dengue and chikungunya in travelers: recent updates

PURPOSE OF REVIEW

Dengue virus (DENV) and chikungunya virus (CHIKV) cause significant morbidity in many world regions and their epidemiology, pathogenesis, vector issues, and control and prevention continue to fascinate researchers. This review focuses on the progress in these areas in the past 2 years.

RECENT FINDINGS

Recent studies have highlighted the features of the epidemiology of DENV and CHIKV in Africa, some places of transmission being detected through travelers as sentinels. Autochthonous transmission of both viruses has been documented in France, raising concern regarding the potential for outbreaks where a competent vector, Aedes albopictus, is present. Some aspects of immune response following DENV and CHIKV infections have been elucidated. New diagnostic techniques for DENV have been explored as well as treatment for CHIKV. Research on Wolbachia as a means of biologic control of mosquito-borne infections including DENV and CHIKV has made significant progress.

SUMMARY

These studies further our understanding of the evolving DENV and CHIKV epidemiology and potential transmission in nonendemic regions, and can contribute to the assessment of travelers. The new information on immunological responses to these viruses influences the vaccine development. Risk factors for severe disease and new therapeutic options could improve current treatment. Finally, research on Wolbachia holds promise in these two important vector-borne viral infections.

A brief review on dengue molecular virology, diagnosis, treatment and prevalence in Pakistan

Dengue virus infection is a serious health problem infecting 2.5 billion people worldwide. Dengue is now endemic in more than 100 countries, including Pakistan. Each year hundreds of people get infected with dengue in Pakistan. Currently, there is no vaccine available for the prevention of Dengue virus infection due to four viral serotypes. Dengue infection can cause death of patients in its most severity, meanwhile many antiviral compounds are being tested against dengue virus infection to eradicate this disease but still there is a need to develop an efficient, low-cost and safe vaccine that can target all the four serotypes of dengue virus. This review summarizes dengue molecular virology, important drug targets, prevalence in Pakistan, diagnosis, treatment and medicinal plant inhibitors against dengue.