血中检测SARS冠状病毒N蛋白在SARS实验室早期诊断中的作用

Detection of N Protein of Severe Acute Respiratory Syndrome Coronavirus(SARS-CoV) in Blood for Early Laboratory Diagnosis

为明确严重急性呼吸综合症(SARS)冠状病毒N蛋白在SARS实验室早期诊断中的作用,通过微量中和试验及酶联免疫方法、间接免疫荧光法检测疑似病人恢复期血清(大于28天)中SARS IgG抗体,确诊SARS患者。同时收集发病不同时期SARS及普通发热病人血清,利用酶联免疫方法检测SARS CoVN蛋白,并与荧光定量PCR早期诊断方法相比较。共检测:广州地区2003年12月～2004年1月新发4例确诊SARS患者不同时期的血液和咽漱液标本;恢复期血清SARS CoV中和抗体阳性病人不同时期的血清46份;广州地区2003年1月～4月临床确诊SARS患者159例的血清和56例疑似患者血清;非SARS普通发热病人血清97份;正常人体检血清100份。结果:4例新发SARS患者的不同时期标本中,3例患者急性期血均检出N蛋白,优于常用的荧光定量PCR检测方法。46份SARS CoV中和抗体阳性的血清标本,N蛋白检出率为100%。159例临床确诊病例中,发病早期5天以内SARS CoVN蛋白的检出率为92 3%,随后呈现逐步下降的趋势,在发病第18天仍可检出。56例临床疑似患者发病早期也有23 2%检出率。而97例普通发热病人及100份正常人血清中均未能检测出SARS CoVN蛋白。表明在血清中检测SARS冠状病毒N蛋白的方法敏感性和特异性都好,对SARS实验室早期诊断具有重要作用。

To further determine the nucleocapsid(N)protein of severe acute respiratory syndrome coronavirus(SARS-CoV)detection as early diagnosis of SARS patients in laboratory, we detected N protein of SARS-CoV in convalescent-phase(more than 30 days)sera of the clinically probable SARS patients who were positive for SARS-IgG antibody by means of micro-neutralization reaction,enzyme-linked immunosorbent assay(ELISA)and indirect immunofluorescent assay(IFA).Meanwhile,we collected a panel of sera from different stages of SARS patients and common febrile patients to detect N protein by ELISA.By comparing with the reverse transcription polymerase chain reaction(RT-PCR),we confirmed ELISA better in N protein detection for early diagnosis of SARS patients in laboratory.Among the sera of four SARS patient specimens collected at different times in Guangzhou this year,three of them were all detected as N protein positive by ELISA at the acute stage, but only one oropharyngeal washing specimen from one SARS patient was detected positive by RT-PCR. In the clinically confirmed SARS specimens,the positivity of the N protein assay was 92.3% within the first five days after onset of symptoms and then decreased day by day,but still could be detected at the eighteenth day.There was 23.4% N protein detection rate in the clinically suspected SARS patients.On the other hand,N protein of SARS-CoV couldn't be detected in the non-SARS febrile patients or the normal persons. Thus,the detection of N protein in the sera of SARS patients is rather important for early laboratory diagnosis.