Development and Validation of Monoclonal Antibody-Based Antigen Capture ELISA for Detection of Group A Porcine Rotavirus

Tris stabilized AuNPs based lateral flow immunochromatography for the simultaneous detection of porcine epidemic diarrhea virus and rotavirus on-site

Porcine epidemic diarrhea virus (PEDV) and rotavirus has posed a significant threat to the pig industry annually across different nations, resulting in huge economic losses. The frequent co-infection of these two viruses in clinical settings complicates the process of differential diagnoses. Rapid and accurate detection of PEDV and rotavirus is in great demand for timely diarrhea disease prevention and control. In this study, tris stabilized AuNPs were prepared and a sensitive lateral flow immunoassay (LFIA) sensor was developed for the simultaneous and rapid detection of PEDV and rotavirus on site. After the system optimization, the established LFIA can simultaneously identify PEDV and rotavirus with limits of detection (LOD) of 1.25 × 103 TCID50 mL-1 and 3.13 × 102 pg mL-1, respectively. When applying for clinical samples, the LFIA show a concordance of 95 % and 100 % to reverse transcript polymerase chain reaction (RT-PCR) for PEDV and rotavirus respectively. Therefore, this LFIA can qualitatively detect PEDV and rotavirus in 18 min with high sensitivity and accuracy without any sophisticated equipment and operation, making it a promising candidate for the early diagnosis of PEDV or/and rotavirus diarrhea on site.

Development and evaluation of polyclonal antibodies based antigen capture ELISA for detection of porcine rotavirus

Rotaviruses are rising as zoonotic viruses worldwide, causing the lethal dehydrating diarrhea in children, piglets, and other livestock of economic importance. A simple, swift, cost-effective, highly specific, and sensitive antigen-capture enzyme-linked immunosorbent assay (AC-ELISA) was developed for detection of porcine rotavirus-A (PoRVA) by employing rabbit (capture antibody) and murine polyclonal antibodies (detector antibody) produced against VP6 of PoRVA (RVA/Pig-tc/CHN/TM-a/2009/G9P23). Reactivity of the both polyclonal antibodies was confirmed by using an indirect ELISA, western-blot analysis and indirect fluorescence assay against rVP6 protein and PoRVA. The detection limit of AC-ELISA was found 50 ng/ml of PoRVA protein. The relative sensitivity and specificity of this in-house AC-ELISA were evaluated for detection of PoRVA from 295 porcine diarrhea samples, and results were compared with that of RT-PCR and TaqMan RT-qPCR. The relative sensitivity and specificity of AC-ELISA compared with those of TaqMan RT-qPCR were found as 94.4 and 99.2%, respectively, with the strong agreement (κ -0.58) between these two techniques. Furthermore, AC-ELISA could not detect any cross-reactivity with porcine epidemic diarrhea virus, transmissible gastro-enteritis virus, pseudo rabies virus and porcine circovirus-2. This in-house AC-ELISA efficiently detected PoRVA from clinical samples, which suggests that this technique can be used for large-scale surveillance and timely detection of rotavirus infection in the porcine farms.

Detection and analysis of rotavirus in clinical stool samples using silver nanoparticle functionalized paper as SERS substrate

Among the different analytical techniques, surface-enhanced Raman scattering (SERS) approach is a widely used technique for the detection and analysis of various chemicals and biological samples. Present study reports a low-cost, sensitive SERS substrate that has an ability to detect rotavirus in clinical stool samples. The proposed SERS substrate has been fabricated through drop-casting of silver nanoparticles (AgNPs) on a printing-grade paper. Rotavirus particles were extracted from clinical stool samples. The presence of rotavirus antigen in stool samples was confirmed using enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction (PCR), and sequencing. The characteristic Raman peaks of rotavirus (RV) particles in solution were found to be significantly enhanced when Raman signals were recorded from the paper-based SERS substrates. Using the proposed SERS substrate, rotavirus samples with concentration as low as 1% could be reliably recorded by the Raman spectrometer. The paper SERS substrate reported herein is an extremely cost-efficient platform and may find applications in other research and clinical laboratories as well.

Development of a droplet digital PCR assay for detection of group A porcine rotavirus

Group A porcine rotavirus (PoRVA) is an important pathogen of acute enteritis in piglets, which has caused severe economic losses in the pig industry worldwide. A convenient, sensitive and specific diagnosis method is an urgent requirement for the surveillance of the PoRVA circulating in clinical samples. In this study, a novel and convenient droplet digital PCR (ddPCR) for the detection of PoRVA was developed using the conserved region of the VP6 gene. The detection limit of ddPCR was 1.81 ± 0.14 copies/rection, ~10 times greater sensitivity than TaqMan real-time quantitative PCR (qPCR). Both ddPCR and qPCR assays exhibited good linearity and repeatability, and the established ddPCR method was highly specific for PoRVA. The results of clinical sample testing showed that the positivity rate of ddPCR (5.6%) was higher than that of qPCR (4.4%). Therefore, the newly developed ddPCR assay could be widely used in clinical diagnosis of PoRVA infections.

Establishment of a reverse transcription recombinase-aided amplification detection method for porcine group a rotavirus

Porcine rotavirus type A (PoRVA) is the main cause of dehydration and diarrhea in piglets, which has a great impact on the development of the pig industry worldwide. A rapid, accurate and sensitive detection method is conducive to the monitoring, control, and removal of PoRVA. In this study, a PoRVA real-time fluorescent reverse transcription recombinase-aided amplification (RT-RAA) assay was developed. Based on the PoRVA VP6 gene, specific primers and probes were designed and synthesized. The sensitivity of RT-RAA and TaqMan probe-based RT-qPCR was 7 copies per reaction and 5 copies per reaction, respectively. The sensitivity of the RT-RAA method was close to TaqMan probe-based RT-qPCR. The detection results of RT-RAA and TaqMan probe-based quantitative real-time RT-PCR methods were completely consistent in 241 clinical samples. Therefore, we successfully established a rapid and specific RT-RAA diagnostic method for PoRVA.

Development and performance evaluation of an In-House ELISA for the detection of group A rotavirus in diarrheal stool samples from children and domestic South American camelids

Group A rotavirus (RVA) is a prevalent pathogen causing acute gastroenteritis (AGE) in young children and animals. We developed an in-house ELISA (ROTA-GeFeK) for RVA detection, based on the expression of native recombinant VP6 protein in E. coli. To detect the RVA antigen, rabbit polyclonal IgG antibodies, produced against rVP6,were used as capture and detector antibodies in a sandwich ELISA. To validate the ROTA-GeFeK, 252 stool samples from children with AGE, were evaluated by conventional RT-PCR and commercial ELISA. Compared to RT-PCR, the ROTAGeFeK had a sensitivity of 88.2 % and a specificity of 94.4 %. Total detection rates with the ROTA-GeFeK, commercial ELISA and RT-PCR were 58 %, 58 % and 64 % respectively. The limit of detection was equal to 2.1 × 10 4 CCID 50 of the RVA strain RIX4414. No cross-reactivity with other enteric pathogens was observed. The RVApositive samples detected by the assay belonged to a diversity of G and [P] genotypes.This assay displayed reactivity and was proved to be useful for the detection of RVA in diarrheal samples of domestic South American Camelids. We suggest that the ROTAGeFeK can be used as an epidemiologic tool for rotavirus surveillance and for RVA detection in other animal species.

ROTADIAL: The first nanobody-based immunoassay to detect Group A Rotavirus

ROTADIAL is a rapid nanobody (Nb)-based ELISA assay able to identify Rotavirus group A (RVA) in feces from pediatric patients. The assay is based on a sandwich of two patented llama-derived Nbs directed to the inner capsid viral protein VP6 from RVA. Nbs are directed to conformational epitopes of VP6 and recognized all human RVA strains tested, representing ideal reagents for their use in immunodiagnostic tests for RVA detection. All the steps are carried out at room temperature, bringing results in less than two hours. This assay, named ROTADIAL, was validated with a reference panel of feces from pediatric patients from Argentina. The overall sensitivity and specificity of the ROTADIAL test, when compared to a commercial test, was 100 % (100/100) and 99 % (99/100) respectively. ROTADIAL presented optimal analytical performance, being capable of detecting RVA regardless of the presence of other common human enteric infectious agents and is the first RVA-diagnostic assay developed using Nbs, worldwide.

Rapid and sensitive detection of rotavirus by surface-enhanced Raman scattering immunochromatography

A surface-enhanced Raman scattering (SERS) immunochromatographic assay (ICA) has been developed for rapid, ultrasensitive, and quantitative detection of rotavirus in feces using double Raman molecule-labeled Au-core Ag-shell nanoparticles. The Raman signals are generated by 5,5'-dithiobis-(2-nitrobenzoic acid) and the intensity of the characteristic peak at 1334^-1 cm was detected as the analytical signal. The Raman signals were enhanced by the SERS-enhanced effect of both Au and Ag, the large amount of Raman molecules, and the hot-spot effect in the narrow gap between the Au core and Ag shell. The SERS ICA can quantitatively detect rotavirus in a concentration range of 8- 40,000 pg/mL, with detection limits of 80 pg/mL and 8 pg/mL based on naked eye observation and SERS signal detection, respectively. No cross-reaction was observed from other common pathogens. The standard deviation of the intra- and inter-batch repetitive tests is less than 10%, and the coincidence between SERS ICA and RT-qPCR as well as commercial colloidal gold ICA is 100%. The results indicated that this SERS ICA is able to quantitatively detect rotavirus in feces in 20 min with high sensitivity, selectivity, reproducibility, and accuracy and might be a promising method for the early detection of rotavirus in clinical analysis.

Synanthropic rodents as virus reservoirs and transmitters

This review focuses on reports of hepatitis E virus, hantavirus, rotavirus, coronavirus, and arenavirus in synanthropic rodents (Rattus rattus, Rattus norvegicus, and Mus musculus) within urban environments. Despite their potential impact on human health, relatively few studies have addressed the monitoring of these viruses in rodents. Comprehensive control and preventive activities should include actions such as the elimination or reduction of rat and mouse populations, sanitary education, reduction of shelters for the animals, and restriction of the access of rodents to residences, water, and food supplies.

Changes of haemogram and serum biochemistry in neonatal piglet diarrhoea associated with porcine rotavirus type A

Porcine rotavirus type A (RVA) is a major cause of neonatal piglet mortality in India. The effect of the disease on haemogram and serum biochemical profile is not well established in piglets. Accordingly, we assessed the haemogram and serum biochemical profile in the neonatal piglet diarrhoea with RVA infection (n = 17). The diagnosis of RVA was confirmed using RNA-polyacrylamide gel electrophoresis (RNA-PAGE), commercially available enzyme-linked immunosorbent assay (ELISA) kit and reverse transcription-polymerase chain reaction (RT-PCR). Non-infected healthy piglets (n = 6) served as control. The concentrations of total protein, albumin, alanine amino transaminase (ALT), aspartate amino transaminase (AST), blood urea nitrogen (BUN) and creatinine in serum were measured by spectrophotometric method. Haemogram was done in the blood using sodium ethylenediaminetetraacetic acid (Na₂ EDTA) as anticoagulant. The mean values of total protein, albumin and globulin concentrations were significantly (P < 0.001) decreased and concentrations of ALT, AST, BUN and creatinine were significantly increased (P < 0.001) in the RVA-infected piglets. Haemogram showed marked haemoconcentration (P < 0.001), leukopenia (P < 0.01) and neutropenia (P < 0.01) in the presence of RVA infection than healthy piglets. The results indicated a possible extra-intestinal spread of RVA in piglets during neonatal diarrhoea. The finding might be helpful to clinicians and while treating such type of clinical cases, incorporation of organ protective drugs will be helpful for better response in the treatment schedule.