Comparison of concentration methods for detection of hepatitis A virus in water samples

Hepatitis A virus is a pathogen associated with water pollution.Contaminated drinking water can cause hepatitis A outbreaks,lead to economic losses,and even threaten human lives.It is difficult to detect low levels of hepatitis A virus in water,so the virus must be concentrated in order to quantify it accurately.Here,we present a simple,rapid,efficient technique for the concentration and detection of hepatitis A virus in water.Our data showed that adding phosphate-buffered saline to the water,pre-filtering the water,and adding Trizol reagent directly to the filtration membrane can significantly improve concentration efficiency.Of three types of filtration membranes studied(mixed cellulose ester membrane,polyvinylidene fluoride membrane,and nylon membrane),the concentration efficiency using mixed cellulose ester membrane with a 0.1-μm pore size was the highest,reaching 92.62 ± 5.17%.This method was used to concentrate hepatitis A virus in water samples from Donghu Lake.Using SYBR Green real-time reverse transcription polymerase chain reaction analysis,the detection sensitivity of this method reached 10~1 copies/μL and its concentration efficiency reached 79.45 ± 9.88%.

SARS-CoV-2 infection causes immunodeficiency in recovered patients by downregulating CD19 expression in B cells via enhancing B-cell metabolism

The SARS-CoV-2 infection causes severe immune disruption.However,it is unclear if disrupted immune regulation still exists and pertains in recovered COVID-19 patients.In our study,we have characterized the immunephe no type of B cells from 15 recovered COVID-19 patients,and found that healthy controls and recovered patients had similar B-cell populations before and after BCR stimulation,but the frequencies of PBC in patients were significantly increased when compared to healthy controls before stimulation.However,the percentage of unswitched memory B cells was decreased in recovered patients but not changed in healthy controls upon BCR stimulation.Interestingly,we found that CD19 expression was significantly reduced in almost all the B-cell subsets in recovered patients.Moreover,the BCR signaling and early B-cell response were disrupted upon BCR stimulation.Mechanistically,we found that the reduced CD19 expression was caused by the dysregulation of cell metabolism.In conclusion,we found that SARS-CoV-2 infection causes immunodeficiency in recovered patients by downregulating CD19 expression in B cells via enhandng B-cell metabolism,which may provide a new intervention target to cure COVID-19.

ARTICLE OPEN Viral dynamics and antibody responses in people with asymptomatic SARS-CoV-2 infection

Over 40% of the coronavirus disease 2019(COVID-19)COVID-19 patients were asymptomatically infected with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)and the immune responses of these asymptomatic individuals is a critical factor for developing the strategy to contain the COVID-19 pandemic.Here,we determined the viral dynamics and antibody responses among 143 asymptomatic individuals identified in a massive screening of more than 5 million people in eight districts of Wuhan in May 2020.Asymptomatic individuals were admitted to the government-designated centralized sites in accordance with policy.The incidence rate of asymptomatic infection is〜2.92/100,000.These individuals had low viral copy numbers(peaked at 315 copies/mL)and short-lived antibody responses with the estimated diminish time of 69 days.The antibody responses in individuals with persistent SARS-CoV-2 infection is much longer with the estimated diminish time of 257 days.These results imply that the immune responses in the asymptomatic individuals are not potent enough for preventing SARS-CoV-2 re-infection,which has recently been reported in recovered COVID-19 patients.This casts doubt on the efficacy of forming"herd-immunity"through natural SARS-CoV-2 infection and urges for the development of safe and effective vaccines.

The regulators of BCR signaling during B cell activation

B lymphocytes produce antibodies under the stimulation of specific antigens,thereby exerting an immune effect.B cells identify antigens by their surface B cell receptor(BCR),which upon stimulation,directs the cell to activate and differentiate into antibody generating plasma cells.Activation of B cells via their BCRs involves signaling pathways that are tightly controlled by various regulators.In this review,we will discuss three major BCR mediated signaling pathways(the PLC-g2 pathway,PI3K pathway and MAPK pathway)and related regulators,which were roughly divided into positive,negative and mutual-balanced regulators,and the specific regulators of the specific signaling pathway based on regulatory effects.