Detection and serotyping of Streptococcus pneumoniae from nasopharyngeal samples by PCR-based multiplex assay

We developed a multiplex PCR-based methodology for nasopharyngeal samples maintained in egg thioglycolate antibiotic and skim milk-tryptone-glucose-glycerol media to identify and serotype the most important serotypes of Streptococcus pneumoniae that cause invasive disease in children. This technique can be used to study the epidemiology of pneumococcal colonization and the effect of conjugate vaccines.     

Evaluation of a new serotyping assay for detection of anti-hepatitis C virus type-specific antibodies in serum samples

The performance of a new version (HC03) of the hepatitis C virus (HCV) serotyping 1-6 assay (Abbott Murex Laboratories), a specific test for serological determination of HCV types, was evaluated using a selected panel of 180 HCV RNA-positive sera. HC03 was more sensitive than the current HC02 version, typing 53 (37.6%) of 141 samples which were not typable with HC02. Furthermore, the HC03 specificity was 94.1% as evaluated with a panel of 22 genotyped samples. This new version of the test improves the quality of the serological approach to HCV type determination.     

Validation of a multiplex pneumococcal serotyping assay with clinical samples

We have recently developed a rapid pneumococcal serotyping method called "multibead assay" (J. Yu et al., J. Clin. Microbiol. 43:156-162, 2005) based on a multiplexed immunoassay for capsular polysaccharides in lysates of pneumococcal cultures. The multibead assay can identify 36 serotypes (1, 2, 3, 4, 5, 6A, 6B, 7A/7F, 8, 9L/9N, 9V, 10A/10B/39/33C, 11A/11D/11F, 12A/12B/12F, 14, 15B/5C, 17F, 18C, 19A, 19F, 20, 22A/22F, 23F, and 33A/33F). More than 90% of the U.S. isolates express one of these serotypes (J. B. Robbins et al., J. Infect. Dis. 148:1136-1159, 1983). To validate the new assay, we examined 495 clinical isolates of pneumococci obtained in Brazil, Denmark, and Mexico. Pneumococci were serotyped by the Neufeld test in their countries of origin, and lysates of each strain were coded and mailed to the United States for the multibead assay at ambient temperature without any thermal protection. After breaking the code, 54 discrepancies (11% of samples) were noted, but 46 were due to nonreproducible technical problems or insufficient growth of the pneumococci. All of the isolates grew well for a second test, and therefore, the culture medium used for the multibead assay is adequate. The discrepancies persisted for eight isolates, involving the 6A, 11A, and 18C serotypes. Additional studies of the eight isolates showed that the discrepancies were due to differences in the reagents used in the multibead or Neufeld tests for these three serotypes. For instance, five isolates were typed as 6A with the Neufeld test but as nontypeable by the multibead assay. Selection of another new monoclonal antibody (Hyp6AG1) for the multibead assay resulted in all five discrepant isolates typing as 6A. This finding indicates the validity of the multibead assay and emphasizes the need to validate any new pneumococcal serotyping assay with a large number of clinical isolates from different locations. It also suggests the presence of serological subtypes among isolates expressing the 6A serotype.     

Development of a multiplex PCR-ligase detection reaction assay for diagnosis of infection by the four parasite species causing malaria in humans

The diagnosis of infections caused by Plasmodium species is critical for understanding the nature of malarial disease, treatment efficacy, malaria control, and public health. The demands of field-based epidemiological studies of malaria will require faster and more sensitive diagnostic methods as new antimalarial drugs and vaccines are explored. We have developed a multiplex PCR-ligase detection reaction (LDR) assay that allows the simultaneous diagnosis of infection by all four parasite species causing malaria in humans. This assay exhibits sensitivity and specificity equal to those of other PCR-based assays, identifying all four human malaria parasite species at levels of parasitemias equal to 1 parasitized erythrocyte/microl of blood. The multiplex PCR-LDR assay goes beyond other PCR-based assays by reducing technical procedures and by detecting intraindividual differences in species-specific levels of parasitemia. Application of the multiplex PCR-LDR assay will provide the sensitivity and specificity expected of PCR-based diagnostic assays and will contribute new insight regarding relationships between the human malaria parasite species and the human host in future epidemiological studies.     

二重逆转录—聚合酶链反应及微孔板反向杂交法检？…

目的 为适应临床上需同时检测庚型肝炎病毒（ＨＧＶ）与丙型肝炎病毒（ＨＣＶ）感染情况，建立了二重逆转录－聚合酶链反应（ＲＴ－ＰＣＲ）及微孔板反向杂交法。方法 根据ＨＣＶ与ＨＧＶ基因与ＨＧＶ特异探针微孔板反向杂交检测ＣＰＲ产物。结果 ＰＣＲ产物经测序，ＨＣＶ与Ｔａｋａｍｉｚａｗａ等及Ｃｈｏｏ等报道的核苷酸同源性分别为９３．１％￣９４．１％与９２．５％￣９３．７％，ＨＧＶ与Ｓｉｍｏｎｓ等、Ｌｉｎｎｅｎ等     

Detection by immunofluorescence of avian myeloblastosis virus reverse transcriptase.

Peripheral blood cells of avian myeloblastosis virus (AMV-(infected chickens were examined at various intervals post infection by immunofluorescence. AMV revertase was identified in pro- and myeloblasts; it was localized mainly in the perinuclear zone or throughout the cytoplasm. No revertase was found in erythrocytes or granulocytes. Blood cells from uninfected chickens of man contained no revertase.