Preliminary report for the application of nucleic acid sequence-based amplification in detection of human cytomegalovirus (HCMV) late pp67 mRNA for diagnosis of HCMV infection.

Human cytomegalovirus (HCMV) late pp67 mRNA expression by nucleic acid sequence-based amplification (NASBA) in patients, clinically diagnosed as possible HCMV, probable HCMV disease, and no disease, was evaluated. The RNAs were isolated from 11 whole-blood samples of 11 patients for the specific amplification of the pp67 mRNA. NASBA results were compared to results from PCR assay and serological assay. The HCMV pp67 mRNA could be found in 3 of 11 patients, whereas, HCMV-DNA PCR was positive in 6 of 11 patients. PCR assay for HCMV-DNA in plasma has proved to correlate with clinical diagnosis of HCMV infection. Only 2 patient samples of NASBA positive results coincided with HCMV-DNA PCR. However, the diagnosis of clinically relevant HCMV infection by NASBA was seen. Anti-CMV IgG titers of 1:1,600 or over 1:1,600 were found in 2 of 3 NASBA positive cases and 5 of 6 HCMV-DNA positive cases, whereas, anti-CMV IgM were all negative. These results showed the correlation of HCMV infection detected by NASBA, PCR assay and anti-CMV IgG of the titers up to 1:1,600. Additionally, a low antibody titer of the HIV patient could be diagnosed by NASBA or PCR. In conclusion, pp67 mRNA NASBA appears to be a promising diagnostic tool in analysis of HCMV infection and/or disease. Its diagnostic value should be defined in the specific group for the follow-up of immunocompromised patients, such as organ transplant recipients in future prospective studies.

Detection of HBV genome by gene amplification method in HBsAg negative blood donors.

The incidence of post-transfusion hepatitis has been reduced greatly by screening blood donors for hepatitis B surface antigen (HBsAg). However, hepatitis B virus infection still accounts for a certain number of cases of post-transfusion hepatitis. The purpose of this study was to detect HBV DNA in the HBsAg negative blood samples by using nested PCR with two primer pairs specific to core region. Two hundreds blood samples from HBsAg negative donors, and 14 samples from HBsAg positive donors were provided by the blood bank of Ramathibodi Hospital. The results showed that HBV DNA was detected in all 14 HBsAg positive blood samples and in 7 (3.5%) of 200 HBsAg negative blood samples. This study showed that the absence of HBsAg in otherwise apparently healthy individuals may not be enough to ensure lack of circulating HBV. The more sensitive ELISA technique is still in need. Otherwise, the safety of blood transfusion can be enhanced by careful selection of blood donors and careful consideration of risks and benefit of the patients who need blood transfusions.