Evaluation of a new ultrafast real-time fluorescence polymerase chain reaction and common assays in the detection of novel Bunya virus

Objective To investigate the specificity and sensitivity of four methods including ultrafastreal-time fluorescence polymerase chain reaction (PCR), real-time fluorescence (RT)-PCR, enzyme-linked immunosorbent assay (ELISA) and gold immunochromatography assay (GICA) for the detection of novel Bunya virus, so as to provide experimental basis for the early diagnosis of severe fever with thrombocytopenia syndrome (SFTS). Methods Serum samples from 86 clinically diagnosis SFTS patients admitted to the Jinan Infectious Diseases Hospital Affiliated to Shandoug University were tested by ultrafast real-time fluorescence PCR, RT-PCR, ELISA and GICA during June 1 to September 30, 2017. Chi-square test was used for statistical analysis. Results Among 86 serum samples, the positive rate of novel Bunya virus of ultrafast real-time fluorescence PCR, RT-PCR, IgM-ELISA, IgG-ELISA, IgM-GICA and IgG-GICA were 82(95.34%), 79(91.86%), 41(47.67%), 8(9.3%), 19(22.09%) and 3(3.49%), respectively. The specificity of ultrafast real-time fluorescence PCR was 100%, and the sensitivity was 1×103 copies/mL.Repeated amplification test showed that the variation coefficient of the computed tomography value was <2%.During phases one, two and three, the positive rates of ultrafast real-time fluorescence PCR were 41(97.62%), 34(94.44%) and 7(87.50%), and RT-PCR were 39(92.86%), 33(91.67%) and 7(87.50%), respectively. During phases one and two, the positive rate of ultrafast real-time fluorescence PCR was slightly higher. The positive rate of anti-novel Bunya virus antibody (IgM) tested by ELISA had a significant increase from phase one (28.57%)to phase three (87.50%). There were statistical differences between phase two and phase, as well as between phase three and phase one (χ2=8.347 and 7.561, respectively, both P<0.01). IgM-GICA also had an increase from phase one (14.29%) to phase two (33.33%)(χ2=3.962, P<0.01), while it was still lower than the other tests.In phase one, the positive rate of RT-PCR was higher than those of ELISA(both IgM and IgG)and GICA(both IgM and IgG)(χ2=33.740, 55.080, 49.010 and 64.340, respectively, all P<0.01). In phase two, the positive rate of RT-PCR was higher than those of ELISA(both IgM and IgG)and GICA(both IgM and IgG) (χ2=7.700, 46.720, 23.700 and 50.630, respectively, all P<0.01). In phase three, the positive rates of ultrafast real-time fluorescence PCR, RT-PCR and IgM-ELISA were equivalent, which were all higher than those of IgG-ELISA and GICA (both IgM and IgG). The positive rates of RT-PCR and IgG-ELISA, IgM-GICA and IgG-GICA were significantly different (all χ2=6.250, all P<0.05). Conclusion In the early detection of novel Bunya virus, ultrafast real-time fluorescence PCR has higher sensitivity, specificity, good repeatability and high stability, which greatly reduces the amplification time compared with the traditional RT-PCR, and is of great value in the early and rapid diagnosis of SFTS. Key words: Novel Bunya virus; Enzyme-linked immunosorbent assay; Ultrafast realtime fluorescence polymerase chain reaction; Realtime fluorescence polymerase chain reaction; Gold immunochromatography assay