Evaluation of a two-test strategy for HIV screening in a low-prevalence setting and the indications for optimizing clinical management.

Objectives: To evaluate a two-test strategy for HIV screening in the low-prevalence population and to assess the feasibility of utilizing the optimal signal-to-cutoff (S/CO) threshold on the chemiluminescence immunoassay(CMIA) and an additional rapid test on the gold immune-chromatography assay (GICA) for screening positive patients and optimization of clinical management. Methods: We conducted a retrospective study of samples analyzed by the fourth-generation Architect HIV Ag/Ab combo assay (CMIA) in a large medical center between June 2017 and August 2020. Reactive samples underwent a second screening test using the rapid test GICA, followed by Western blot (WB) as the confirmatory test. Receiver operating characteristic (ROC) curve analysis was used to determine the optimal S/CO. We calculated sensitivity, specificity, and predictive value based on our population. The performance of the single-test strategy (CMIA) was compared with that of the two-test strategy (CMIA and GICA). Logistic regression was used to analyze the factors of clinical characteristics leading to false positive results. Results: A total of 220558 samples were screened by CMIA, and 429 patients met the inclusion criteria. Of these, CMIA produced 199 false-positive results with a median S/CO of 1.93(IQR1.45-3.68) and 230 positive results with a median S/CO of 455.1 (IQR169.3-709.7). The optimal S/CO of the single-test strategy was 8.82, which achieved a sensitivity of 100% and a positive predictive value (PPV) of 90.9%. The two-test strategy (CMIA and GICA) provided a sensitivity of 100% and a PPV of 98.7%, which best correlated with the confirmatory test WB. The combination of S/CO 8.82 on the CMIA assay and additional test results of GICA can be defined as four types used to interpret HIV serostatus. The false positive rate (FPR) was high in the female, the age≤18 group, the pre-operative patients, and the patients from the clinical departments of Pediatrics, Gynecology and Obstetrics, and Oncology, etc. Conclusions: The false positive rate is high in the low-prevalence setting by using CMIA. The two-test strategy (CMIA and GICA) is recommended for HIV screening in hospitals. Hopefully, the clinicians will be able to interpret HIV serostatus and facilitate clinical decision-making while waiting for the confirmatory results.

SARS-CoV-2 detection using quantum dot fluorescence immunochromatography combined with isothermal amplification and CRISPR/Cas13a.

The development of reliable, sensitive, and fast devices for the diagnosis of COVID-19 is of great importance in the pandemic of the new coronavirus. Here, we proposed a new principle of analysis based on a combination of reverse transcription and isothermal amplification of a fragment of the gene encoding the S protein of the SARS-CoV-2 and the CRISPR/Cas13a reaction for cleavage of the specific probe. As a result, the destroyed probe cannot be detected on an immunochromatographic strip using quantum fluorescent dots. Besides, the results can be obtained by an available and inexpensive portable device. By detecting SARS-CoV-2 negative (n = 25) and positive (n = 62) clinical samples including throat swabs, sputum and anal swabs, the assay showed good sensitivity and specificity of the method and could be completed within 1 h without complicated operation and expensive equipment. These superiorities showed its potential for fast point-of-care screening of SARS-CoV-2 during the outbreak, especially in remote and underdeveloped areas with limited equipment and resources.

[Detection of procalcitonin based on fluorescence immune chromatography].

Procalcitonin (PCT) is the precursor of calcitonin related to the severity of human bacterial infection. We made a test strip by coupling anti-PCT to quantum dot, in order to develop a highly sensitive and convenient PCT testing product. The anti-PCT titer had reached 107 because of the stability by coupling anti-PCT with quantum dot. The detecting linear range of the experiment was 0.15 to 120 µg/L, the sensitivity was 0.007 µg/L, the recovery range was 91% to 113%, and the intra- and inter-assay coefficient of variation was less than 8%. Comparing the homemade fluorescence-detected test strip with PCT ELISA kit on sale, we got accurate results which could mostly accomplish the test of clinical samples.

Rapid detection of quantum dot immune chromatography nasopharyngeal carcinoma EBNA1 antibody.

This study explored the 605 nm carboxyl of water-soluble quantum dots to assess the practicability of the nasopharyngeal carcinoma marker EBNA1 antibody. We used 605 nm carboxyl water-soluble quantum dots and nasopharyngeal carcinoma EBNA1 antigen in 1-(3-dimethylaminopropyl-3-2-ethylcarbonimine hydrochloride to generate quantum dot-labeled antigen. Gel imaging system showed that serum group and 60 patients with nasopharyngeal carcinoma had significant differences in 30 cases of normal adult serogroup brightness, Levene test in the two groups ELISA absorbance value was P<0.001, namely the nasopharyngeal carcinoma group and the normal adult serum group measured absorbance value difference was obvious. The statistical significance, and the detection technology were of high specificity and sensitivity. In conclusion, this study adopted double antigen clip combining immune chromatography test EBNA1 antibody in serum, compared with the traditional enzyme-linked immunoassays this method is more rapid, with simpler operation, rapid detection for developing quantum dot immune chromatography technology the EBNA1 antibody kit provides a theoretical basis.

Detection of procalcitonin based on fluorescence immune chromatography / 生物工程学报

Procalcitonin (PCT) is the precursor of calcitonin related to the severity of human bacterial infection. We made a test strip by coupling anti-PCT to quantum dot, in order to develop a highly sensitive and convenient PCT testing product. The anti-PCT titer had reached 10⁷ because of the stability by coupling anti-PCT with quantum dot. The detecting linear range of the experiment was 0.15 to 120 μg/L, the sensitivity was 0.007 μg/L, the recovery range was 91% to 113%, and the intra- and inter-assay coefficient of variation was less than 8%. Comparing the homemade fluorescence-detected test strip with PCT ELISA kit on sale, we got accurate results which could mostly accomplish the test of clinical samples.

An area CCD-based detection system for up-converting phosphor immune lateral flow assay / 军事医学

Objective To make portable the detector for up-converting phosphor (UCP) immune lateral flow assay portable and increase the test precision by developing an area CCD-based detection system for UCP immune lateral flow assay.Methods The excitation light source was a 980 nm and 300 mW laser diode.In order to decrease the error induced by the un-uniformity of laser irradiation,a uniformity mirror was inserted in the beam and a calibration algorithm was optimized.The residual error from the un-uniformity irradiation was less than 1％.Results Thanks to the adjustability of the exposure time,the dynamic range of detection of the system was as high as 106 dB.The repeat test error for the very low signal was 1％ (variation coefficient).The linear correlation coefficient between the tested T/C value and sample concentration was 0.998.Conclusion Compared to is traditional instrument,this detection system is static,portable and highly precise.

Comparison of three kinds common methods in detection of hepatitis B / 中国医师进修杂志

ObjectiveTo investigate the clinical application value of enzyme-linked immunosorbent assay (ELISA) and time-resolved fluorescence analysis(TRFIA) and latex immune chromatography (GICA) in detecting hepatitis B serum markers.MethodsOne hundred and forty-five suspected patients of hepatitis B were detected serum markers of hepatitis B by ELISA,TRFIA and GICA method,and the results were compared and analyzed.ResultsWhen TRFIA method was as gold standard,the positive coincidence rate of ELISA and GICA method in HBsAg,HBeAb,HBcAb was 71％ (57/80),45％ (36/80),and in HBsAb,HBeAb,HBcAb was 33％( 1/3),0 (0/3),and there were significant differences between two methods (P＜0.05 ) ; the others were no significant differences (P ＞ 0.05 ).There was significant difference in the sensitivity of HBsAg between ELISA method and GICA method (P ＜ 0.05 ),but there was no significant difference in HBsAb,HBeAg,HBeAb,HBcAb(P ＞ 0.05 ).There was no significant difference in the specificity of HBsAg,HBsAb,HBsAg,HBeAb and HBcAb between ELISA method and GICA method (P ＞0.05).There was significant difference in HBsAg among three methods(P ＜0.05),but there was no significant difference between ELISA method and TRFIA method (P＞0.05),and there was significant difference between GICA method and TRFIA method (P＜0.05).There was no significant difference in HBsAb,HBeAg,HBeAb and HBcAb among three methods (P ＞ 0.05 ); there was significant difference in both HBsAb and HBeAb positive among three methods (P ＜ 0.05),and there was significant difference between ELISA method,GICA method and TRFIA method (P＜ 0.05).ConclusionTRFIA method has supreme measuring range,sensitivity and specificity supreme,but the price is higher;ELISA method is in the intermediate level of three methods and price is cheap,and it as well as TRFIA is suitable for the batch detection; GICA accuracy is low,but quick and simple,it is more suitable for the complement of the first two methods.

Importancia de las pruebas específicas e inespecíficas para el diagnóstico de sífilis en donantes de sangre / Importance of specific and unspecific tests to diagnosis syphilis in blood donors

Con la finalidad de mejorar el diagnóstico de laboratorio de sífilis como enfermedad infecto contagiosa en donantes de sangre, se realizó el presente estudio cuyo objetivo es determinar las pruebas serológicas específicas: Inmunoanálisis Enzimático (ELISA), Inmunocromatografía (IC) e inespecíficas: Laboratorio de investigación de enfermedades venéreas (VDRL) y Reaginas séricas no calentadas (USR) más confiable para el descarte de sífilis en donantes de sangre del Hospital Dr. Adolfo Pons de Maracaibo, estado Zulia. Se analizaron 481 sueros de donantes de sangre aparentemente sanos, de ambos sexos en edades comprendidas entre 18 y 60 años. Del total de muestras analizadas por ELISA 10 resultaron positivas (2,07 por ciento) y 8 (1,66 por ciento) por IC. El VDRL captó 4 (0,82 por ciento) sueros con reactividad y USR sólo 2 sueros (0,41 por ciento). Se concluye que la prueba de ELISA conjuntamente con el VDRL son las herramientas más seguras y fidedignos para el descarte de sífilis en donantes de sangre, dado que proporcionan en paralelo resultados confiables, fidedigno que garantice la calidad de la misma al ser transfundida

In order to improve the laboratory diagnosis of syphilis as an infectious and contagious disease in blood donors, we performed this study to determine the reliability of the specific: Enzyme Immunoassay (Elisa) and Immune-chromatography (IC) tests, the unspecific: Venereal Disease Research Laboratory (VDRL) test and the Unheated serum regain (USR) Serologic tests to rule out syphilis from blood donors of the Dr Adolfo Pons Hospital in Maracaibo, Zulia state. We analyzed 481 sera from apparently healthy blood donors, male and female, 18 to 60 years of ages. From the samples analyzed by Elisa 10 were positive (2.07 percent) and 8 (1.66 percent) by IC. VDRL detected 4 (0.82 percent) reactive sera and USR just 2 (0.421 percent). We concluded that Elisa with VDRL are the safest and more reliable tests to rule out syphilis from blood donors, since they gave in parallel reliable results to assure the quality of blood to be transfused