A new silver amplification immunochromatography system compared with conventional rapid antigen assay for the diagnosis of influenza A and B / 中国感染与化疗杂志

Objective To analyze the consistency of two rapid antigen assays for the diagnosis of influenza A and B. We evaluated the clinical usefulness of silver amplification immunochromatography influenza virus detection kit.Methods Nasopharyngeal swab samples were collected from patients who were suspected of influenza at Huashan Hospital between January and February 2015. Two samples were collected from the same one patient. The samples were tested simultaneously by using IMMUNO AG Cartridge Flu AB kit (AG1) and commercial immunochromatographic assay kit, Clearview exact influenza A&B (CV). PCR method was used as reference.Results A total of 91 samples were tested, of which 7 were positive for influenza A and 53 positive for influenza B by AG1 system; 7 positive for influenza A and 50 positive for influenza B by CV system; and 8 positive for influenza A and 60 positive for influenza B by PCR. The sensitivity and specificity of the AG1 system were 87.5 % and 100 % for influenza A, and 88.3 % and 100 % for influenza B; while the CV system showed sensitivity and specficity of 87.5 % and 100 % for influenza A, 83.3 % and 100 % for influenza B. The AG1 system was 100 % consistent with the CV system in the positive rate of influenza A, and 94.3 % consistent with the CV system in the positive rate of influenza B.Conclusions The AG1 system is well consistent with the conventional immunochromatography-based diagnostic tests in diagnosis of influenza. The AG1 system is useful in earlier diagnosis of influenza due to fewer human error in result interpretation.

Incidence, severity, prognostic significance of thrombocytopenia in malaria.

Background: Malaria is an infectious disease caused by plasmodium parasite. P. falciparum account for majority of morbidity and mortality. Thrombocytopenia and anaemia are the most frequently associated hematological complications in malaria. The low platelet count together with acute febrile syndrome emerged as the strongest predictor of malaria a finding that is frequent and present even before anemia and splenomegaly sets in. Severe thrombocytopenia is a good predictor of poor prognosis than mild and moderate thrombocytopenia. The aim is to study the incidence, severity, prognostic significance of thrombocytopenia in malaria. Methods: This was an observational and prospective study. The study enrolled 100 patients with thrombocytopenia and fever who were proven to have malaria either by peripheral smear or Quantitative Buffy Coat (QBC) test or malarial antigen assay were included in the study and patients with thrombocytopenia due to other causes were excluded from the study. Platelet count was estimated on a fully automated quantitative analyzer. All the 100 patients were followed during the hospital stay and upto discharge or till the outcome. Results: The incidence of thrombocytopenia was 73% indicating a common association in malaria. Complicated malaria was observed in 58.80% of P. falciparum infection whereas 66% of P. vivax infection was associated with uncomplicated malaria. Severe thrombocytopenia showed positive correlation with severity of malaria. Thrombocytopenic patients with effective anti-malarial treatment showed 95.90% recovery and 3 patients 4.10% had mortality. Patients with severe thrombocytopenia were 8.5 times more likely to have complicated malaria with P <0.001 according to student „t‟ test. Conclusion: Thrombocytopenia is the most common hematological finding in malaria. Severe thrombocytopenia showed positive correlation with complicated malaria and a good predictor of poor prognosis. Patients with classical malarial fever and thrombocytopenia who were negative for malaria parasite were not included in the study.

Usefulness of serological ELISA assay for Taenia saginata to detect naturally infected bovines / Utilização de teste sorológico ELISA para a detecção de bovinos naturalmente infectados por Taenia saginata

Bovine cysticercosis, a cosmopolitan disease caused by Taenia saginata, leads to economic losses due to carcass devaluation at slaughter. Sanitary inspection at slaughterhouses, the routine diagnostic method in Brazil, lacks the necessary sensitivity to detect the mildly infected cattle that are typically encoutered in Brazil. In this study we have tested cattle sera from animals diagnosed as positive and negative by veterianry inspection for (1) anti-parasite antibodies using metacestodes antigens (T. solium vesicular fluid and T. saginata secretions) and (2) the HP10 secreted antigen of viable metacestodes. The cut-off values were calculated by ROC curve for intense and mild infections conditions, and by the classical method ( X + 2DP for negative samples). The sensitivity and specificity of these diagnostic tests were different depending on the assumed cut-off value and, importantly, whether the infection was mild or intense. In spite of these observations, however, such ELISA assays for serum antibodies and parasite antigens constitute an important tool for epidemiological porposes, and in establishing priorities for the control of bovine cysticercosis.

A cisticercose bovina, uma doença cosmopolita causada pela Taenia saginata, resulta em perdas econômicas devido á desvalorização de carcaças durante o abate. A inspeção sanitária nos frigoríficos, método de diagnóstico de rotina no Brasil, não possui sensibilidade necessária para detectar animais levemente infectados, os quais são tipicamente encontrados no Brasil. Neste estudo testou-se soro de animais diagnosticados positivos e negativos pela inspeção veterinária por (1) anticorpos anti-parasita usando antígenos de metacestóides (fluido vesicular de T. solium e secreções de T. saginata) e (2) antígeno secretado de metacestóides viáveis. Os pontos de corte foram calculados pela curva ROC, considerando condições de intensa e leve infeção, e pelo método clássicoo ( X + 2DP das amostras negativas).. A sensibilidade e a especificidade dos testes diagnósticos foram diferentes dependendo do valor de ponto de corte assumido e, sobretudo, se a infecção era intensa ou leve. Apesar destas observações, no entanto, tanto o ensaio ELISA para anticorpos séricos quanto para antígeno de parasita constituem importante ferramenta para propósitos epidemiológicos e no estabelecimento de prioridades no controle da cisticercose bovina.

Dengue NS1 antigen detection: A useful tool in early diagnosis of dengue virus infection.

Purpose: This study was undertaken to evaluate the efficacy of NS1 antigen (Ag) assay as an early marker for dengue virus (DV) infection. Materials and Methods: Group I evaluated the performance of NS1 antigen (Ag) assay in comparison to MAC-ELISA and their detection rate when performed together in a single sample. Six hundred acute/early convalescent sera were screened by both the assays. Group II evaluated the efficacy of a single assay in 30 acute phase sera of paediatric OPD patients screened only by NS1 Ag assay. Group III evaluated the specificity of NS1 assay in comparison to MAC-ELISA on 40 samples included as controls. Results: In Group I, 140 (23.3%) and 235 (39.1%) samples were positive by NS1 assay and MAC-ELISA respectively. The detection rate increased to 320 (53.3%) when both the assays were used together on a single sample. NS1 Ag positivity varied from 71.42% to 28.4% in acute and early convalescent sera, conversely IgM detection rate was 93.61% and 6.38% in early convalescent and acute phase sera respectively (P < 0.0001). In Group II, 66.66% (20) samples were positive by NS1 assay. All the samples in Group III were negative showing 100% specificity of both the assays. Conclusion: NS1 Ag assay holds promise in early diagnosis of dengue infection. When used in combination with MAC-ELISA on a single sample it significantly improves the diagnostic algorithm without the requirement of paired sera.

Development and verification of an ELISA for quantitatively detecting Japanese encephalitis virus antigen / 临床检验杂志

Objective To develop a double antibody sandwich ELISA for quantitatively detecting Japanese encephalitis virus(JEV) antigen.Methods The anti-JEV polyclonal antibodies were used to coat ELISA plates.Anti-JEV monoclonal antibodies were used as enzyme-labeled conjugate.A standard curve based on known amounts of JEP antigen was established by the ELISA.Various parameters of the assay were analyzed.Results The optimal linear range was 12.5～200 U/ml(r=0.9989).The quantitation limit was 12.5 U/ml.The recovery rate for the accuracy test was 85.0%～103.3%.The coefficients of variation for intra-assay and inter-assay precision were 4.3%and 5.5%respectively.No cross-reaction was observed with HAV vaccine,influenza vaccine,Vero cell Iysates,newborn bovine serum,or human albumin.Conclusions The data indicate that the ELISA developed in this study has high specificity,precision, accuracy,and stability.The assay should be suitable for quantitative determination of JEV antigen in various vaccine products.

HIV-1 p24 Antigen Detection by Immune Complex Dissociation and Neutralization in HIV-1 Infected Persons in Korea / 감염

BACKGROUND: HIV-1 p24 antigen assay is useful for the detection of circulating viruses, and infection prior to seroconversion. However, circulating HIV-1 p24 antigen may be complexed with HIV antibody and prevent it from being detected by antigen capture assay. To detect HIV-1 p24 antigen in the specimen, it is necessary to dissociate immune complexes and confirm the presence of HIV-1 p24 antigen after the neutralization with the specific antibody. METHODS: We tested 32 sera from HIV-1 infected persons who were diagnosed from 1987 tO1996 in Korea for HIV-1 p24 antigen by enzyme linked immunosorbent assay (ELISA.) with or without the dissociation of immune complexes. And we confirmed the antigen assay results by the neutralization with HIV-1 specific antibody as a confirmatory test. We also calculated the concentration of HIV-1 p24 antigen in each specimen. RESULTS: Eleven of 32 sera tested were initially positive for HIV-1 p24 antigen. After the dissociation of immune complexes for 29 sera except two of which signal/cutoff ratios were higher than 7.0 and except one which was not enough for the assay,13 were shown to be positive for HIV-1 p24 antigen and their signal/cutoff ratios were increased by 10 times. Five of antigen negative cases were turned to be positive after the immune complex dissociation. After neutralization with HIV-1specific p24 antibody for sera of 13 which were positive for HIV-1 p24 antigen with or without the immune complex dissociation, all were shown to be neutralized. We have observed more than 90% neutralization reduction for 12 sera and more than 50% less than 90% for one. The average concentration of HIV-1 p24 antigen was8.76pg/ml by antigen assay and was increased to 76.81~g/m~ after immune complex dissociation. CONCLUSION: We concluded that the sensitivity and the specificity of HIV-1 p24 antigen assay could be increased by dissociation of the immune complexes and neutralization with the specific antibody.