Pattern of pulsed-field gel electrophoresis of <i>Vibrio parahaemolyticus</i> (VP) from 19 cases and food handler A with culture-positive specimens.

<p>The pattern from the specimen of food handler A showed 91.1–100% homology to those from 19 cases.</p

The sensitivity and specificity of the four methods when analyzing field samples.

<p>The sensitivity and specificity of the four methods when analyzing field samples.</p

Enhanced immunity against SARS-CoV-2 in returning Chinese individuals

Global COVID-19 vaccination programs effectively contained the fast spread of SARS-CoV-2. Characterizing the immunity status of returned populations will favor understanding the achievement of herd immunity and long-term management of COVID-19 in China. Individuals were recruited from 7 quarantine stations in Guangzhou, China. Blood and throat swab specimens were collected from participants, and their immunity status was determined through competitive ELISA, microneutralization assay and enzyme-linked FluoroSpot assay. A total of 272 subjects were involved in the questionnaire survey, of whom 235 (86.4%) were returning Chinese individuals and 37 (13.6%) were foreigners. Blood and throat swab specimens were collected from 108 returning Chinese individuals. Neutralizing antibodies against SARS-CoV-2 were detected in ~90% of returning Chinese individuals, either in the primary or the homologous and heterologous booster vaccination group. The serum NAb titers were significantly decreased against SARS-CoV-2 Omicron BA.5, BF.7, BQ.1 and XBB.1 compared with the prototype virus. However, memory T-cell responses, including specific IFN-γ and IL-2 responses, were not different in either group. Smoking, alcohol consumption, SARS-CoV-2 infection, COVID-19 vaccination, and the time interval between last vaccination and sampling were independent influencing factors for NAb titers against prototype SARS-CoV-2 and variants of concern. The vaccine dose was the unique common influencing factor for Omicron subvariants. Enhanced immunity against SARS-CoV-2 was established in returning Chinese individuals who were exposed to reinfection and vaccination. Domestic residents will benefit from booster homologous or heterologous COVID-19 vaccination after reopening of China, which is also useful against breakthrough infection.</p

Schematic diagram for the Vch-UPT-LF assay.

<p>(A) An up-converting phosphor technology-based lateral flow assay for simultaneous detection of <i>V</i>. <i>cholerae</i> O1 and O139, namely Vch-UPT-LF, was established with antibodies against O1 and O139 as test line 1 and test line 2 dispensed on an analytical membrane at the strip, respectively. (B) After sample addition, the UCP-antibody complexes flowed forward with the liquid sample. (C) Positive signals were generated for test line 1 or test line 2 when the samples contained <i>V</i>. <i>cholerae</i> O1 or O139. The accuracy and precision of Vch-UPT-LF depended on stable signals on the C line, which were maintained by rabbit anti-goat IgG independently bound with UCP-goat IgG.</p

Specificity of the UPT-LF strips.

<p>(A) VchO1-UPT-LF and (B) VchO139-UPT-LF, namely the up-converting phosphor technology-based lateral flow (UPT-LF) assay for detection of O1 or O139, showed excellent specificity for 15 non-O1/nonO139 <i>V</i>. <i>cholerae</i> strains, and they are also specific for 15 O139 and 15 O1 isolates respectively. (C) VchO1-UPT-LF, (D) VchO139-UPT-LF, (E) channel 1 and (F) channel 2 of the UPT-LF strip for simultaneous detection of O1 and O139 (Vch-UPT-LF), did not generate false-positive results for seven other <i>vibrio</i> species and nine food-borne pathogens.</p

Development and evaluation of an up-converting phosphor technology-based lateral flow assay for the rapid, simultaneous detection of <i>Vibrio cholerae</i> serogroups O1 and O139

<div><p><i>Vibrio cholerae</i> serogroups O1 and O139 are etiological agents of cholera, a serious and acute diarrheal disease, and rapid detection of <i>V</i>. <i>cholerae</i> is a key method for preventing and controlling cholera epidemics. Here, a point of care testing (POCT) method called Vch-UPT-LF, which is an up-converting phosphor technology-based lateral flow (UPT-LF) assay with a dual-target detection mode, was developed to detect <i>V</i>. <i>cholerae</i> O1 and O139 simultaneously from one sample loading. Although applying an independent reaction pair made both detection results for the two Vch-UPT-LF detection channels more stable, the sensitivity slightly declined from 10⁴ to 10⁵ colony-forming units (CFU) mL⁻¹ compared with that of the single-target assay, while the quantification ranges covering four orders of magnitude were maintained. The strip showed excellent specificity for seven <i>Vibrio</i> species that are highly related genetically, and nine food-borne species whose transmission routes are similar to those of <i>V</i>. <i>cholerae</i>. The legitimate arrangement of the two adjacent test lines lessened the mutual impact of the quantitation results between the two targets, and the quantification values did not differ by more than one order of magnitude when the samples contained high concentrations of both <i>V</i>. <i>cholerae</i> O1 and O139. Under pre-incubation conditions, 1×10¹ CFU mL⁻¹ of <i>V</i>. <i>cholerae</i> O1 or O139 could be detected in fewer than 7 h, while the Vch-UPT-LF assay exhibited sensitivity as high as a real-time fluorescent polymerase chain reaction with fewer false-positive results. Therefore, successful development of Vch-UPT-LF as a dual-target assay for quantitative detection makes this assay a good candidate POCT method for the detection and surveillance of epidemic cholera.</p></div

Simultaneous detection of <i>V</i>. <i>cholerae</i> O1 and O139 using the Vch-UPT-LF strip.

<p>(A) For simultaneous detection of O1 and O139 at a series of concentrations, the sensitivity of channel 1 of the up-converting phosphor technology-based lateral flow assay for simultaneous detection of O1 and O139 (Vch-UPT-LF) for detecting <i>V</i>. <i>cholerae</i> O1 was maintained. (B) The sensitivity of channel 2 of Vch-UPT-LF for detecting <i>V</i>. <i>cholerae</i> O139 decreased ten-fold. All quantification deviations were less than one order of magnitude.</p