Recent Development in Detection Systems for Human Viral Pathogens from Clinical Samples with Special Reference to Biosensors

Over the last few decades, the emergence and re-emergence of various pathogenic viruses have significantly impacted human health. The continuous rise in cases with increasing mortality rates has driven the chase for effective treatment options and early diagnosis to combat this global health issue. Currently, used laboratory techniques for virus detection require complex equipment, trained personnel, and, most importantly, are time-consuming. In times of outbreaks and epidemics like COVID-19 and Ebola, easy-to-use and point-of-care tests, especially for developing and underdeveloped countries, are indispensable. This chapter explicitly discusses the availability of the detection methods for various human viral pathogens with their shortcomings and recent advancements in biosensors. With the ongoing improvement in biosensors, these hold important avenues for rapid, sensitive, and scalable devices for viral diagnostic purposes. The effectiveness of previously known and current approaches/devices/methods that utilize different principles for detection has also been reviewed here, with the listing of all the available tests for various human pathogens. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023.

Time series analysis revealed prognostic value of continuous nasopharyngeal SARS-CoV-2 nucleic acid quantification for COVID-19: A retrospective study of >3000 COVID-19 patients from 2 centers.

BACKGROUND: Early stratification of disease progression remains one of the major challenges towards the post-coronavirus disease 2019 (COVID-19) era. The clinical relevance of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid load is debated due to the heterogeneity in patients' underlying health conditions. We determined the prognostic value of nasopharyngeal viral load dynamic conversion for COVID-19. METHODS: The cycling threshold (Ct) values of 28,937 nasopharyngeal SARS-CoV-2 RT-PCRs were retrospectively collected from 3,364 COVID-19 patients during hospitalization and coordinated to the onset of disease progression. The ROC curve was utilized to determine the predictive performance of the rate of Ct value alteration between two consecutive RT-PCR runs within 48 h (ΔCt%) for disease transformation across patients with different COVID-19 severity and immune backgrounds, and further validated with 1,860 SARS-CoV-2 RT-PCR results from an independent validation cohort of 262 patients. For the 67 patients with severe COVID-19, Kaplan-Meier analysis was performed to evaluate the difference in survival between patients stratified by the magnitude of Ct value alteration between the late and early stages of hospitalization. RESULTS: The kinetics of viral nucleic acid conversion diversified across COVID-19 patients with different clinical characteristics and disease severities. The ΔCt% is a clinical characteristic- and host immune status-independent indicator for COVID-19 progression prediction (AUC = 0.79, 95 % CI = 0.76 to 0.81), which outperformed the canonical blood test markers, including c-reactive protein (AUC = 0.57, 95 % CI = 0.53 to 0.61), serum amyloid A (AUC = 0.61, 95 % CI = 0.54 to 0.68), lactate dehydrogenase (AUC = 0.61, 95 % CI = 0.56 to 0.67), d-dimer (AUC = 0.56, 95 % CI = 0.46 to 0.66), and lymphocyte count (AUC = 0.62, 95 % CI = 0.58 to 0.66). Patients with persistent high SARS-CoV-2 viral load (an increase of mean Ct value < 50 %) during the first 3 days of hospitalization demonstrated a significantly unfavorable survival (HR = 0.16, 95 % CI = 0.04 to 0.65, P = 2.41 × 10-3). CONCLUSIONS: Viral nucleic acid dynamics of SARS-CoV-2 eliminates the inter-patient variance of basic health conditions and therefore, can serve as a prognostic marker for COVID-19.

Pulsed blue light inactivates two strains of human coronavirus.

Emerging evidence suggests that blue light has the potential to inactivate viruses. Therefore, we investigated the effect of 405 nm, 410 nm, 425 nm and 450 nm pulsed blue light (PBL) on human alpha coronavirus HCoV-229 E and human beta coronavirus HCoV-OC43, using Qubit fluorometry and RT-LAMP to quantitate the amount of nucleic acid in irradiated and control samples. Like SARS-CoV-2, HCoV-229E and HCoV-OC43 are single stranded RNA viruses transmitted by air and direct contact; they have similar genomic sizes as SARS-CoV-2, and are used as surrogates for SARS-CoV-2. Irradiation was carried out either at 32.4 J cm-2 using 3 mW cm-2 irradiance or at 130 J cm-2 using 12 mW cm-2 irradiance. Results: (1) At each wavelength tested, PBL was antiviral against both coronaviruses. (2) 405 nm light gave the best result, yielding 52.3% (2.37 log10) inactivation against HCoV-OC43 (p < .0001), and a significant 1.46 log 10 (44%) inactivation of HCoV-229E (p < .01). HCoV-OC43, which like SARS-CoV-2 is a beta coronavirus, was more susceptible to PBL irradiation than alpha coronavirus HCoV-229E. The latter finding suggests that PBL is potentially antiviral against multiple coronavirus strains, and that, while its potency may vary from one virus to another, it seems more antiviral against beta coronaviruses, such as HCoV-OC43. (3) Further, the antiviral effect of PBL was better at a higher irradiance than a lower irradiance, and this indicates that with further refinement, a protocol capable of yielding 100% inactivation of viruses is attainable.

Early therapeutic interventions of traditional Chinese medicine in COVID-19 patients: A retrospective cohort study.

OBJECTIVE: To observe the early interventions of traditional Chinese Medicine (TCM) on the conversion time of nucleic acid in patients with coronavirus disease 2019 (COVID-19), and find possible underlying mechanisms of action. METHODS: A retrospective cohort study was conducted on 300 confirmed COVID-19 patients who were treated with TCM, at a designated hospital in China. The patients were categorized into three groups: TCM1, TCM2 and TCM3, who respectively received TCM interventions within 7, 8-14, and greater than 15 days of hospitalization. Different indicators such as the conversion time of pharyngeal swab nucleic acid, the conversion time of fecal nucleic acid, length of hospital stay, and inflammatory markers (leukocyte count, and lymphocyte count and percentage) were analyzed to observe the impact of early TCM interventions on these groups. RESULTS: The median conversion times of pharyngeal swab nucleic acid in the three groups were 5.5, 7 and 16 d (P < 0.001), with TCM1 and TCM2 being statistically different from TCM3 (P < 0.01). TCM1 (P < 0.05) and TCM3 (P < 0.01) were statistically different from TCM2. The median conversion times of fecal nucleic acid in the three groups were 7, 9 and 17 d (P < 0.001). Conversion times of fecal nucleic acid in TCM1 were statistically different from TCM3 and TCM2 (P < 0.01). The median lengths of hospital stay in the three groups were 13, 16 and 21 d (P < 0.001). TCM1 and TCM2 were statistically different from TCM3 (P < 0.01); TCM1 and TCM3 were statistically different from TCM2 (P < 0.01). Both leucocyte and lymphocyte counts increased gradually with an increase in the length of hospital stay in TCM1 group patients, with a statistically significant difference observed at each time point in the group (P < 0.001). Statistically significant differences in lymphocyte count and percentage in TCM2 (P < 0.001), and in leucocyte count (P = 0.043) and lymphocyte count (P = 0.038) in TCM3 were observed. The comparison among the three groups showed a statistically significant difference in lymphocyte percentage on the third day of admission (P = 0.044). CONCLUSION: In this study, it was observed that in COVID-19 patients treated with a combination of Chinese and Western medicines, TCM intervention earlier in the hospital stay correlated with faster conversion time of pharyngeal swab and fecal nucleic acid, as well as shorter length of hospital stay, thus helping promote faster recovery of the patient. The underlying mechanism of action may be related to improving inflammation in patients with COVID-19.

The N gene of SARS-CoV-2 was the main positive component in repositive samples from a cohort of COVID-19 patients in Wuhan, China.

BACKGROUND: Repositivity of SARS-CoV-2 nucleic acid in discharged COVID-19 patients was reported recently. However, the characteristics of repositive results are still not well understood, leading to a lack of effective monitoring strategies. METHODS: In the present study, a total of 59 COVID-19 patients were enrolled, and the characteristics of the repositive samples were analyzed. RESULTS: The repositive rate in this cohort was 15.79%. The N gene was the main target gene that was positive in the repositive results as well as in the last positive results of all patients. The median duration from diagnosis to the last positive test was 20 days (IQR, 16-31 days), and the longest duration was 40 days. Repositivity was only observed in IgM single- or both IgM- and IgG-positive patients, instead of IgG single-positive patients. CONCLUSIONS: There was a significant proportion of repositives in the recovered COVID-19 patients, and increasing the required number of negatives for consecutive nucleic acid tests may reduce the incidence of repositives. The recommended monitoring strategy for repositivity is monitoring the N gene in IgM-positive patients. This can ensure high sensitivity while reducing the time and cost of nucleic acid detection.

Clinical characteristics and outcomes of COVID-19 patients with gastrointestinal symptoms admitted to Jianghan Fangcang Shelter Hospital in Wuhan, China.

Coronavirus disease 2019 (COVID-19) is a health emergency worldwide, and gastrointestinal (GI) symptoms are increasingly reported in COVID-19 patients. However, sample size was small and the incidence of GI symptoms in patients was variable across studies, and the correlation between these symptoms and clinical outcomes remains incompletely understood. The objective of this study is to compare clinical characteristics and outcomes between patients with and without GI symptoms admitted to Jianghan Fangcang Shelter Hospital in Wuhan. This retrospective study recruited 1320 COVID-19 patients admitted to hospital from 5 February 2020 to 9 March 2020. On the basis of the presence of GI symptoms, the sample was divided into a GI group (n = 192) and a non-GI group (n = 1128). The three most common GI symptoms were diarrhea (8.1%), anorexia (4.7%), and nausea and vomiting (4.3%). The rate of clinical deterioration was significantly higher in the GI group than in the non-GI group (15.6% vs. 10.1%, P = .032). GI symptoms (P = .045), male gender P < .001), and increased C-reactive protein (P = .008) were independent risk factors for clinical worsening. This study demonstrated that the rate of clinical deterioration was significantly higher in the GI group. Furthermore, potential risk factors for developing GI symptoms, male gender, and increased C-reactive protein can help clinicians predict clinical outcomes in COVID-19 patients.

Different longitudinal patterns of nucleic acid and serology testing results based on disease severity of COVID-19 patients.

Effective strategy to mitigate the ongoing pandemic of 2019 novel coronavirus (COVID-19) require a comprehensive understanding of humoral responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the emerging virus causing COVID-19. The dynamic profile of viral replication and shedding along with viral antigen specific antibody responses among COVID-19 patients started to be reported but there is no consensus on their patterns. Here, we conducted a serial investigation on 21 individuals infected with SARS-CoV-2 in two medical centres from Jiangsu Province, including 11 non-severe COVID-19 patients, and 5 severe COVID-19 patients and 5 asymptomatic carriers based on nucleic acid test and clinical symptoms. The longitudinal swab samples and sera were collected from these people for viral RNA testing and antibody responses, respectively. Our data revealed different pattern of seroconversion among these groups. All 11 non-severe COVID-19 patients and 5 severe COVID-19 patients were seroconverted during hospitalization or follow-up period, suggesting that serological testing is a complementary assay to nucleic acid test for those symptomatic COVID-19 patients. Of note, immediate antibody responses were identified among severe cases, compared to non-severe cases. On the other hand, only one were seroconverted for asymptomatic carriers. The SARS-CoV-2 specific antibody responses were well-maintained during the observation period. Such information is of immediate relevance and would assist COVID-19 clinical diagnosis, prognosis and vaccine design.

[Bronchoalveolar lavage fluid was used to diagnose two cases of 2019-nCoV infection].

The case reports 2 cases of novel coronavirus pneumonia diagnosed by concurrent bronchoalveolar lavage in our hospital, 1 case had a history of epidemiology, clinical symptoms and high imaging suspicion, but repeated negative throat swabs. One patient was diagnosed 2019-nCoV. Before the patient was discharged, the clinical symptoms disappeared, the chest CT showed significant improvement, and the pharynx swab was twice negative, reaching the discharge standard.We detected the ORF 1ab gene, the N gene and the nucleic acid of the new coronavirus in the broncho-alveolar lavage fluid of 2 patients. The results showed that the positive rate of bronchoalveolar lavage for detection of new coronavirus nucleic acid was high, and bronchoalveolar lavage for suspected or confirmed new coronavirus pneumonia patients with negative detection of nucleic acid in pharynx swabs but still residual lung lesions was helpful for early diagnosis, treatment and prognosis.