A Real-Time RT-PCR Assay for Genotyping of Rotavirus

Development of RT-dPCR method and reference material for rotavirus G3P8 and G9P8

The rotavirus (RV) is the predominant causative pathogen associated with acute gastroenteritis in children aged below 5 years, leading to an annual mortality rate of 200,000 infants globally. Despite the development of a vaccine, it exacerbates the medical burden around the world. Here, we have developed reverse transcription digital PCR (RT-dPCR) methods for precise and absolute quantification of nucleic acid in rotavirus G3P8 and G9P8. The pseudovirus reference material (RM) contained the RNA fragment encoding VP4 and VP7. The assigned values with expanded uncertainty were determined as (2432 ± 510) copies/μL and (3406 ± 613) copies/μL. The RM and RT-dPCR methods were employed to validate various digital platforms, revealing the inadequate performance of platform III, which could potentially result in "false-negative" outcomes. The application of RT-dPCR techniques and pseudovirus RM confers advantages in the diagnosis of RV-induced diseases, thereby enhancing the survival rate of young children suffering from acute gastroenteritis.

Possible viral agents to consider in the differential diagnosis of blepharoconjunctivitis

BACKGROUND

Blepharoconjunctivitis poses a diagnostic challenge due to its diverse etiology, including viral infections. Blepharoconjunctivits can be acute or chronic, self-limiting, or needing medical therapy.

AIM

To review possible viral agents crucial for accurate differential diagnosis in cases of blepharoconjunctivitis.

METHODS

The PubMed database was searched for records relating to viral blepharoconjunctivitis. The search string generated was "("virally"[All Fields] OR "virals"[All Fields] OR "virology"[MeSH Terms] OR "virology"[All Fields] OR "viral"[All Fields]) AND "Blepharoconjunctivitis"[All Fields]".

RESULTS

A total of 24 publications were generated from the search string. Reference lists from each relevant article were also searched for more information and included in this review. Viral etiologies such as adenovirus, herpes simplex virus (HSV), varicella-zoster virus (VZV), and Epstein-Barr virus (EBV) are frequently implicated. Adenoviral infections manifest with follicular conjunctivitis and preauricular lymphadenopathy, often presenting as epidemic keratoconjunctivitis. HSV and VZV infections can result in herpetic keratitis and may exhibit characteristic dendritic corneal ulcers. EBV, although less common, can cause unilateral or bilateral follicular conjunctivitis, particularly in immunocompromised individuals. Other potential viral agents, such as enteroviruses and molluscum contagiosum virus, should also be considered, especially in pediatric cases.

CONCLUSION

Prompt recognition of these viral etiologies is essential for appropriate management and prevention of complications. Thus, a thorough understanding of the clinical presentation, epidemiology, and diagnostic modalities is crucial for accurate identification and management of viral blepharoconjunctivitis.

Efficient SARS-CoV-2 Surveillance during the Pandemic-Endemic Transition Using PCR-Based Genotyping Assays

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants of concern (VOC) pose an increased risk to public health due to higher transmissibility and/or immune escape. In this study, we assessed the performance of a custom TaqMan SARS-CoV-2 mutation panel consisting of 10 selected real-time PCR (RT-PCR) genotyping assays compared to whole-genome sequencing (WGS) for identification of 5 VOC circulating in The Netherlands. SARS-CoV-2 positive samples (N = 664), collected during routine PCR screening (15 ≤ CT ≤ 32) between May-July 2021 and December 2021-January 2022, were selected and analyzed using the RT-PCR genotyping assays. VOC lineage was determined based on the detected mutation profile. In parallel, all samples underwent WGS with the Ion AmpliSeq SARS-CoV-2 research panel. Among 664 SARS-CoV-2 positive samples, the RT-PCR genotyping assays classified 31.2% as Alpha (N = 207); 48.9% as Delta (N = 325); 19.4% as Omicron (N = 129), 0.3% as Beta (N = 2), and 1 sample as a non-VOC. Matching results were obtained using WGS in 100% of the samples. RT-PCR genotyping assays enable accurate detection of SARS-CoV-2 VOC. Furthermore, they are easily implementable, and the costs and turnaround time are significantly reduced compared to WGS. For this reason, a higher proportion of SARS-CoV-2 positive cases in the VOC surveillance testing can be included, while reserving valuable WGS resources for identification of new variants. Therefore, RT-PCR genotyping assays would be a powerful method to include in SARS-CoV-2 surveillance testing. IMPORTANCE The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) genome changes constantly. It is estimated that there are thousands of variants of SARS-CoV-2 by now. Some of those variants, variants of concern (VOC), pose an increased risk to public health due to higher transmissibility and/or immune escape. Pathogen surveillance helps researchers, epidemiologists, and public health officials to monitor the evolution of infectious diseases agents, alert on the spread of pathogens, and develop counter measures like vaccines. The technique used for the pathogen surveillance is called sequence analysis which makes it possible to examine the building blocks of SARS-CoV-2. In this study, a new PCR method based on the detection of specific changes of those building blocks is presented. This method enables a fast, accurate and cheap determination of different SARS-CoV-2 VOC. Therefore, it would be a powerful method to include in SARS-CoV-2 surveillance testing.

Development of a rapid homogeneous immunoassay for detection of rotavirus in stool samples

Rotavirus is the main pathogen causing acute viral gastroenteritis. Accurate and rapid diagnosis of rotavirus infection is important to determine appropriate treatment, prevention of unnecessary antibiotics use and control of infection spread. In this study, we established a rapid, accurate, and sensitive amplified luminescent proximity homogeneous assay linked immunosorbent assay (AlphaLISA) for detecting rotavirus and evaluated its efficacy in human stool samples. Our results demonstrated that the sensitivity of AlphaLISA (5⁻⁸) significantly exceeded that of the immunochromatographic assay (ICA, 5⁻⁴) for rotavirus antigen detection. The intra-assay and inter-assay coefficients of variation were 2.99–3.85% and 5.27–6.51%, respectively. Furthermore, AlphaLISA was specific for rotavirus and did not cross-react with other common diarrhea viruses. AlphaLISA and real-time reverse transcription polymerase chain reaction (RT-qPCR, which is considered a gold standard for detecting diarrhea viruses) tests showed consistent results on 235 stool samples, with an overall consistency rate of 97.87% and a kappa value of 0.894 (P < 0.001). The overall consistency rate of ICA compared with RT-qPCR was 95.74%. AlphaLISA showed better consistency with RT-qPCR than the routinely used ICA for rotavirus detection in stool samples. The AlphaLISA method can be used in clinical practice for the rapid, accurate, and sensitive detection of rotavirus infection.

Detection and characterization of rotavirus G and P types from children with acute gastroenteritis in Qom, central Iran

AIM

The aim of the study is to estimate the burden of Rotavirus gastroenteritis as well as predominant genotypes of Rotavirus among children less than 5 years of age referring to Pediatric University Hospital in Qom, Iran.

BACKGROUND

Gastroenteritis is the fourth most common cause of death and accounts for 16% of all deaths in children <5 years of age worldwide.

METHODS

During two years, 130 patients referring to a pediatric hospital were enrolled in this study. After RNA extraction, Rotaviruses were detected by the VP6 gene. Then, G-typing (G1, G2, G3, G4, G8, G9, and G12) and P-typing (P4, P6, and P8) were performed using RT-PCR and specific primers.

RESULTS

The results of the PCR revealed that from a total of 130 patients, 22 cases (16.9%) showed positive VP6 by RT-PCR. G1 was mostly the predominant serotype (27%), accounting for 22% of all VP7-positive isolates, followed by G9 (18%), G2 (9%), G3 (9%), and G4 (9%). None of the strains revealed the presence of G8 genotype (0%), and 5 specimens (23%) were non-typable. The frequency of P typing was P8 (50%), P6 (23%), P4 (14%), and 3 samples were P-non-typable (13%), respectively. The dominant G-P combination was G1 [8] (32%).

CONCLUSION

Such studies based on typing methods assists in the Rotavirus vaccine introduction by policymakers and design of new effective vaccines.