Objective To investigate the role of human parvovirus B19 (HPV B19) infection in the occurrence of aplastic anemia (AA) and idiopathic thrombocytopenic purpura (ITP) Methods From April 1995 to October 1996 sixty four patients (40 cases of AA and 24 cases of ITP) at Xijing Hospital were enrolled in this study Among them, 38 were boys, 26 girls, with age ranging from 1 to 12 years Control group consisted of 30 healthy children during the same period From each of them, 2?ml of peripheral blood was taken For the nested polymerase chain reaction (PCR) study, 50?μl of serum was added to a 100?μl of solution containing 10?μg of proteinase K, which was incubated at 65℃ for 1 hour and then at 95℃ for 10 minutes to inactivate the proteinase K The formed precipitate was then centrifuged at 14?000 ?r/m for 15 minutes, and 5?μl of the supernatant was used as the PCR template The nested PCR amplification was done as follows: 5?μl of each template Department of Pediatrics, Xijing Hospital,the Fourth Military Medical University, Xi’an 710032, China (Qian XH, Zheng YJ, Jiao XY and Zhang GC) This study was supported by the Starting Fund for Returned Scholars of PLA (No 947008) was added to reach 50?μl of PCR reaction volume, containing 31?μl of bidistilled water, 5?μl of buffer, 200?μmol/L of each dNTP, 1 unit Taq DNA polymerase and 300?ng of each primer Thirty five cycles of both first and second round PCR amplification were performed under the following conditions: 95℃ for 1 minute, 55℃ for 1 5 minutes, and 72℃ for 1 minute The amplified fragments were 1112?bp and 104?bp respectively The second PCR product was electrophoresed on 2% agarose gel, and visualized in UV light The band position was compared with that of HPV B19 DNA positive control Results The samples of sera obtained from 40 AA patients, 24 ITP patients and 30 healthy children were analyzed for the HPV B19 DNA The positive rates of HPV B19 DNA were 25 0 (10/40) and 29 2 (7/24) in AA and ITP patients respectively, which were significantly higher than those in the control group (3 3%, P <0 05) Conclusion HPV B19 infection is closely related to the onset of AA, as well as ITP, and may be an important cause of childhood AA and ITP Objective To investigate the role of human parvovirus B19 (HPV B19) infection in the occurrence of aplastic anemia (AA) and idiopathic thrombocytopenic purpura (ITP) Methods From April 1995 to October 1996 sixty four patients (40 cases of AA and 24 cases of ITP ) at Xijing Hospital were enrolled in this study Among them, 38 were boys, 26 girls, with age ranging from 1 to 12 years Control group consisted of 30 healthy children during the same period From each of them, 2? ml of peripheral blood was For For the nested polymerase chain reaction (PCR) study, 50 μl of serum was added to a 100 μl of solution containing 10 μg of proteinase K, which was incubated at 65 ° C for 1 hour and then at 95 ° C for 10 minutes to inactivate the proteinase K The formed precipitate was then centrifuged at 14000? r / m for 15 minutes, and 5? μl of the supernatant was used as the PCR template The nested PCR amplification was done as follows: 5? μl of each template Department of Pediatric s, Xijing Hospital, the Fourth Military Medical University, Xi’an 710032, China (Qian XH, Zheng YJ, Jiao XY and Zhang GC) This study was supported by the Starting Fund for Returned Scholars of PLA (No 947008) was added to Reach 50 μl of PCR reaction volume containing 31 μl of bidistilled water, 5 μl of buffer, 200 μmol / L of each dNTP, 1 unit Taq DNA polymerase and 300 ng of each primer Thirty five cycles of both first and second round PCR amplification were performed under the following conditions: 95 ° C for 1 minute, 55 ° C for 1 5 minutes, and 72 ° C for 1 minute The amplified fragments were 1112 bp and 104 bp respectively The second PCR product was electrophoresed on 2% agarose gel, and visualized in UV light The band position was compared with that of HPV B19 DNA positive control Results The samples of sera obtained from 40 AA patients, 24 ITP patients and 30 healthy children were analyzed for HPV HPV DNA 19 rates of HPV B19 DNA were 25 0 (10/40) and 29 2(7/24) in AA and ITP patients respectively, which were significantly higher than those in the control group (3 3%, P <0 05) Conclusion HPV B19 infection is closely related to the onset of AA, as well as ITP, and may be an important cause of childhood AA and ITP