ObjectiveTo develop and verify a multiplex real-time RT-PCR assay for simultaneous identification of human parainfluenza virus type 1(HPIV1),type 2(HPIV2)and type 3(HPIV3).MethodsThe whole genome sequences of HPIV1,HPIV2 and HPIV3 were downloaded from the database for alignment analysis,and the conserved regions were selected. Specific primers and probes were designed for the three viruses respectively to develop a multiplex real-time RTPCR assay with human ribonuclease P(RNase P)as theinternal quality control. The method was verified for the sensitivity,specificity and precision and used to detect 192 clinical samples.ResultsAfter optimization,the multiplex real-time RTPCR reaction system was determined to be 30 μL,including 10 × NeoscriptRTase/UNG Multi mix 3 μL,5 × Neoscript RT Premix Multi Buffer 6 μL,upstream and downstream primers of HPIV1,HPIV2 and HPIV3(100 μmol/L)0. 1 μL respectively,HPIV1,HPIV2,HPIV3 probes(100 μmol/L)0. 05 μL respectively,RNase P upstream and downstream primers(50 μmol/L)0. 06 μL respectively,RNase P probe(50 μmol/L)0. 03 μL respectively,template 15 μL,and ddH2O supplemented to 30 μL. The reaction conditions were 50 ℃ 20 min,95 ℃ 3 min and 45 cycles of 95 ℃ 15 s and54 ℃ 30 s. Fluorescence signals were collected during annealing in each cycle. The minimum detection limits of HPIV1,HPIV2 and HPIV3 were all 500 copies/mL by the multiplex real-time RT-PCR assay;The method showed no cross-reaction with influenza A virus,influenza B virus,respiratory syncytial virus andnovel coronaviruses. The coefficients of variation(CVs)in intra-and inter-groups of the recombinant plasmid standard mixture with three different concentrations were all less than 3%. HPIV1,HPIV2 and HPIV3 were detected in 192 clinical samples,and the positive rates were7. 81%,0. 05% and 3. 1%,respectively.ConclusionThe multiplex real-time RT-PCR assay for detection of HPIV1,HPIV2 and HPIV3 developed in this study has good sensitivity,specificity and precision,which has a high clinical application prospect in the field of rapid diagnosis and identification of HPIV.