Sensitive Detection of Influenza A (H1N1) Virus by Isothermal Amplification in A Single Tube

The peculiar characteristics and advancement in diagnostic methodologies of influenza A virus

Influenza A virus (IAV) is a significant public health concern, causing seasonal outbreaks and occasional pandemics. These outbreaks result from changes in the virus's surface proteins which include hemagglutinin and neuraminidase. Influenza A virus has a vast reservoir, including wild birds, pigs, horses, domestic and marine animals. It has over 130 subtypes based on differences in hemagglutinin and neuraminidase protein. IAV affects all age groups but impacts young children more especially during the colder season. Despite the development of vaccines and antiviral drugs, IAV is still a major cause of respiratory illnesses and deaths. Surveillance of IAV is crucial to detect new strains and assess vaccine effectiveness. Detection of IAV relies on methods like hemagglutination assay, PCR, cell culturing, and immunochromatography-based tests. Precise and early detection of IAV strain is crucial for quick treatment using antiviral drugs and unraveling epidemiological patterns to curb epidemics and pandemics on time. Advancements in diagnostic methodologies have enabled us to detect the IAV at early stages by overcoming the limitations of previously used diagnostic tests, further preparing us to combat future epidemics more effectively. This review article discusses the traditional and advanced diagnosis methods for detecting IAV.

Rapid detection of human influenza A viruses by HFman probe-based loop-mediated isothermal amplification assays

Since China abandoned the zero-COVID policy at the end of 2022, a wave of severe Flu pandemic emerged in China. Rapid and accurate diagnosis of Influenza A virus (IAV) is critical for clinical management and therapeutic decision-making of patients with fever. Here, we reported a novel IAV HF-LAMP assay, which can be performed with purified RNA or directly using clinical samples. The assays with purified RNA and clinical samples have high sensitivity with limit of detection (LOD) of 9.6 copies/reaction, 9900 copies/mL, and short sample-to-answer times of 36 and 50 min, respectively. Both assays showed high specificity and significantly higher IAV detection rate than the rapid antigen detection (RAD) assays. Furthermore, we found the vast majority (91.2 %) of children with fever during the pandemic were infected by IAV, and current IAV infection has a very narrow detectable window. The novel IVA HF-LAMP assays will provide robust tools to facilitate early diagnosis of IAV infection in current and future seasonal influenza epidemics.

Rapid detection of collagens using a closed-tube LAMP method

Identification methods of collagens and gelatins have been studied many years due to religious and food safety issues. Some researchers detected the collagen while others took up their study based on DNA at the first time. In this work, we used a closed-tube loop-mediated isothermal amplification (LAMP) technique to differentiate collagen and gelatin samples. DNA was extracted by DNeasy mericon Food Kit and was dissolved in 30 µl elution buffer, optimum concentration of Mg²⁺, deoxyribonucleoside triphosphates(dNTPs), betaine in LAMP reaction is 6.0 mmol/L, 2.0 mmol/L, and 0.8 mmol/L, respectively. After LAMP reaction, samples being detected changed their initial color to green, others' were colorless or brown slightly. The research offered a simple, fast detection technique to differentiate collagen and gelatin samples derived from porcine, bovine and channel catfish (Ictalurus punctatus) , the collagens' species can be determined by color variation in reaction tubes within two hour.

Comparison and evaluation of two diagnostic methods for detection of npt II and GUS genes in Nicotiana tabacum

To diminish the time required for some diagnostic assays including polymerase chain reaction (PCR), loop-mediated isothermal amplification (LAMP) and also a visual detection protocol on the basis of npt II and GUS genes in transgenic tobacco plants were used. Agrobacterium tumefaciens-mediated transformation of Nicotiana tabacum leaf discs was performed with plant transformation vector of pBI 121. From kanamycin-resistant plants selected by their antibiotic resistance, four plants were selected for DNA isolation. Presence of the transgene was confirmed in the transformants by PCR and LAMP. In this regard, all LAMP and PCR primers were designed on the basis of the gene sequences of npt II and GUS. The LAMP assay was applied for direct detection of gene marker from plant samples without DNA extraction steps (direct LAMP assay). Also, a novel colorimetric LAMP assay for rapid and easy detection of npt II and GUS genes was developed here, its potential compared with PCR assay. The LAMP method, on the whole, had the following advantages over the PCR method: easy detection, high sensitivity, high efficiency, simple manipulation, safety, low cost, and user friendly.