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We have expressed in Escherichia coli functionally active proteins encoded by two human cDNAs that were isolated previously by using rat 3 alpha-hydroxysteroid dehydrogenase cDNA as the probe. The expressed proteins catalyzed the interconversion between 5 alpha-dihydrotestosterone and 5 alpha-androstane-3 alpha,17 beta-diol. Therefore, we name these two enzymes type I and type II 3 alpha-hydroxysteroid dehydrogenases. The type I enzyme has a high affinity for dihydrotestosterone, whereas the type II enzyme has a low affinity for the substrate. The tissue-specific distribution of these two enzymes was determined by reverse transcription polymerase chain reaction using gene-specific oligonucleotide primers. The mRNA transcript of the type I enzyme was found only in the liver, whereas that of the type II enzyme appeared in the brain, kidney, liver, lung, placenta, and testis. The structure and sequence of the genes encoding these two 3 alpha-hydroxysteroid dehydrogenases were determined by analysis of genomic clones that were isolated from a lambda EMBL3 SP6/T7 library. The genes coding for the type I and type II enzymes were found to span approximately 20 and 16 kilobase pairs, respectively, and to consist of 9 exons of the same sizes and boundaries. The exons range in size from 77 to 223 base pairs (bp), whereas the introns range in size from 375 bp to approximately 6 kilobase pairs. The type I gene contains a TATA box that is located 27 bp upstream of multiple transcription start sites. In contrast, the type II gene contains two tandem AP2 sequences juxtaposed to a single transcription start site.

). To complement this biochemical analysis, we undertook a genetic approach to the analysis of the structure and function of the A20 protein. Here we report the application of clustered charge-to-alanine mutagenesis of the A20 gene. Eight mutant viruses containing altered A20 alleles were isolated using this approach; two of these, tsA20-6 and tsA20-ER5, have tight temperature-sensitive phenotypes. At the nonpermissive temperature, neither virus forms macroscopic plaques and the yield of infectious virus is <1% of that obtained at the permissive temperature. Both viruses show a profound defect in the accumulation of viral DNA at the nonpermissive temperature, although both the A20 protein and DNA polymerase accumulate to wild-type levels. Cytoplasmic extracts prepared from cells infected with the tsA20 viruses show a defect in processive polymerase activity; they are unable to direct the formation of RFII product using a singly primed M13 template. In sum, these data indicate that the A20 protein plays an essential role in the viral life cycle and that viruses with A20 lesions exhibit a DNA ؊ phenotype that is correlated with a loss in processive polymerase activity as assayed in vitro. The vaccinia virus A20 protein can, therefore, be considered a new member of the family of proteins (E9, B1, D4, and D5) with essential roles in vaccinia virus DNA replication.Vaccinia virus, the prototypic member of the poxvirus family, displays a great deal of genetic and physical autonomy from the host. The virus replicates solely within the cytoplasm of the host, and the 192-kb genome is thought to encode most if not all of the functions required for genome replication, gene expression, and virion morphogenesis. The centerpiece of the replication apparatus is the E9 DNA polymerase, which displays significant homology to the ␣ and ␦ families of eucaryotic replicative polymerases as well as the polymerases encoded by herpesviruses. We and others have characterized the polymerase both genetically and biochemically (4, 5,9, 10, 12, 29-31, 36, 38, 39, 41). Temperature-sensitive (ts) alleles, mutator and anti-mutator alleles, and mutants conferring resistance to aphidicolin, phosphonoacetic acid, and cytosine arabinoside have been isolated and studied. The polymerase has been overexpressed and purified and shown to have both polymerase and proofreading exonuclease activities. We have also shown that the enzyme is inherently distributive in vitro, being able to catalyze the addition of Ͻ10 nucleotides (nt) per binding event when moderate levels of salt (40 mM NaCl) or divalent cations (8 mM MgCl 2 ) are present (31). In sharp contrast, the cytoplasmic lysates of infected cells are able to catalyze the addition of as many as 7,000 nt in a single binding event under the same reaction conditions (29). We demonstrated that the protein(s) responsible for conferring processivity on the viral polymerase was present in extracts prepared from infected cells in which only early proteins were present but not in extracts prepared from uninfect...

Respiratory disease caused by atypical bacteria remains an important cause of morbidity and mortality for adults and children, despite the widespread use of effective antimicrobials agents. Culture remains the "gold standard" for the detection of these agents. However, culture is labor-intensive, takes several days to weeks for growth, and can be very insensitive for the detection of some of these organisms. Newer singleplex PCR diagnostic tests are sensitive and specific, but multiple assays would be needed to detect all of the common pathogens. Therefore, we developed the Pneumoplex assays, a multiplex PCR-enzyme hybridization assay (the standard assay) and a multiplex real-time assay to detect the most common atypical pathogens in a single test. Primer and probe sequences were designed from conserved regions of specific genes for each of these organisms. The limits of detection were as follows: for Bordetella pertussis, 2 CFU/ml; for Legionella pneumophila (serotypes 1 to 15) and Legionella micdadei, 9 and 80 CFU/ml, respectively; for Mycoplasma pneumoniae, 5 CFU/ml; and for Chlamydia (Chlamydophila) pneumoniae, 0.01 50% tissue culture infective doses. Recombinant DNA controls for each of these organisms were constructed, and the number of copies for each DNA control was calculated. The Pneumoplex could detect each DNA control down to 10 copies/ml. The analytical specificity demonstrated no cross-reactivity between 23 common respiratory pathogens. One hundred twenty-five clinical bronchoalveolar lavage fluid samples tested by the standard assay demonstrated that the Pneumoplex yielded a sensitivity and a specificity of 100 and 98.5%, respectively. This test has the potential to assist clinicians in establishing a specific etiologic diagnosis before initiating therapy, to decrease hospital costs, and to prevent inappropriate antimicrobial therapy.

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Human adenoviruses (AdV) have been implicated in a wide variety of diseases and are ubiquitous in populations worldwide. These agents are of concern particularly in immunocompromised patients, children, and military recruits, resulting in severe disease or death. Clinical diagnosis of AdV is usually achieved through routine viral cell culture, which can take weeks for results. Immunofluorescence and enzyme-linked immunosorbent assay-based techniques are more timely but lack sensitivity. The ability to distinguish between the six different AdV species (A to F) is diagnostically relevant, as infections with specific AdV species are often associated with unique clinical outcomes and epidemiological features. Therefore, we developed a multiplex PCR-enzyme hybridization assay, the Adenoplex, using primers to the fiber gene that can simultaneously detect all six AdV species A through F in a single test. The limit of detection (LOD) based on the viral 50% tissue culture infective dose/ml for AdV A, B, C, D, E, and F was 10 ؊2 , 10 ؊1 , 10 ؊1 , 10 ؊2 , 10 ؊1 , and 10 ؊2 , respectively. Similarly, the LOD for the six DNA controls ranged from 10 2 to 10 3 copies/ml. Twelve common respiratory pathogens were tested with the Adenoplex, and no cross-reactivity was observed. We also validated our assay using clinical specimens spiked with different concentrations of AdV strains of each species type and tested by multiplex PCR and culture. The results demonstrated an overall sensitivity and specificity of Adenoplex of 100%. This assay can be completed in as few as 5 h and provides a rapid, specific, and sensitive method to detect and subtype AdV species A through F.Human adenoviruses (AdV) cause a variety of diseases and are prevalent throughout the world. Common clinical manifestations resulting from AdV infection include pneumonia, cystitis, conjunctivitis, diarrhea, hepatitis, myocarditis, and encephalitis (10). In the general population, AdV often cause mild or self-limiting disease; however, severe disseminated disease can occur in immunocompromised individuals and can be fatal. Pediatric bone marrow transplant patients are at increased risk for AdV infection and have high mortality rates (22). Discontinuation of vaccinating U.S. military trainees against AdV has resulted in a resurgence of respiratory disease epidemics in this population, leading to increased AdV morbidity (12, 15).There are currently 51 recognized AdV serotypes that have been grouped into six different species (formerly subgenera), A to F, based on their physiochemical, biological, and genetic properties (3, 21). Identification of AdV species types can be particularly useful to clinicians, as specific species can cause infections with unique clinical outcomes and epidemiological features. For example, the ability to distinguish between group D AdV, which cause severe and highly contagious keratoconjunctivitis, and group B and E AdV, which cause mild ocular infections, may be of great clinical importance. Also, species typing may help identify disease fro...

Assays to simultaneously detect multiple potential agents of bioterrorism are limited. Two multiplex PCR and RT-PCR enzyme hybridization assays (mPCR-EHA, mRT-PCR-EHA) were developed to simultaneously detect many of the CDC category “A” bioterrorism agents. The “Bio T” DNA assay was developed to detect: Variola major (VM), Bacillus anthracis (BA), Yersinia pestis (YP), Francisella tularensis (FT) and Varicella zoster virus (VZV). The “Bio T” RNA assay (mRT-PCR-EHA) was developed to detect: Ebola virus (Ebola), Lassa fever virus (Lassa), Rift Valley fever (RVF), Hantavirus Sin Nombre species (HSN) and dengue virus (serotypes 1–4). Sensitivity and specificity of the 2 assays were tested by using genomic DNA, recombinant plasmid positive controls, RNA transcripts controls, surrogate (spiked) clinical samples and common respiratory pathogens. The analytical sensitivity (limit of detection (LOD)) of the DNA asssay for genomic DNA was 1×100∼1×102 copies/mL for BA, FT and YP. The LOD for VZV whole organism was 1×10−2 TCID50/mL. The LOD for recombinant controls ranged from 1×102∼1×103copies/mL for BA, FT, YP and VM. The RNA assay demonstrated LOD for RNA transcript controls of 1×104∼1×106 copies/mL without extraction and 1×105∼1×106 copies/mL with extraction for Ebola, RVF, Lassa and HSN. The LOD for dengue whole organisms was ∼1×10−4 dilution for dengue 1 and 2, 1×104 LD50/mL and 1×102 LD50/mL for dengue 3 and 4. The LOD without extraction for recombinant plasmid DNA controls was ∼1×103 copies/mL (1.5 input copies/reaction) for Ebola, RVF, Lassa and HSN. No cross-reactivity of primers and probes used in both assays was detected with common respiratory pathogens or between targeted analytes. Clinical sensitivity was estimated using 264 surrogate clinical samples tested with the BioT DNA assay and 549 samples tested with the BioT RNA assay. The clinical specificity is 99.6% and 99.8% for BioT DNA assay and BioT RNA assay, respectively. The surrogate sensitivities of these two assays were 100% (95%CI 83–100) for FT, BA (pX02), YP, VM, VZV, dengue 2,3,4 and 95% (95%CI 75–100) for BA (pX01) and dengue 1 using spiked clinical specimens. The specificity of both BioT multiplex assays on spiked specimens was 100% (95% CI 99–100). Compared to other available assays (culture, serology, PCR, etc.) both the BioT DNA mPCR-EHA and BioT RNA mRT-PCR-EHA are rapid, sensitive and specific assays for detecting many category “A” Bioterrorism agents using a standard thermocycler.

Vaccinia virus encodes two protein kinases (B1 and F10) and a dual-specificity phosphatase (VH1), suggesting that phosphorylation and dephosphorylation of substrates on serine/threonine and tyrosine residues are important in regulating diverse aspects of the viral life cycle. Using a recombinant in which expression of the H1 phosphatase can be regulated experimentally (vindH1), we have previously demonstrated that repression of H1 leads to the maturation of noninfectious virions that contain several hyperphosphorylated substrates (K. Liu et al., J. Virol. 69:7823–7834). In this report, we demonstrate that among these is a 25-kDa protein that is phosphorylated on tyrosine residues in H1-deficient virions and can be dephosphorylated by recombinant H1. We demonstrate that the 25-kDa phosphoprotein represents the product of the A17 gene and that A17 is phosphorylated on serine, threonine, and tyrosine residues during infection. Detection of phosphotyrosine within A17 is abrogated when Tyr203 (but not Tyr3, Tyr6, or Tyr7) is mutated to phenylalanine, suggesting strongly that this amino acid is the site of tyrosine phosphorylation. Phosphorylation of A17 fails to occur during nonpermissive infections performed with temperature-sensitive mutants defective in the F10 kinase. Our data suggest that this enzyme, which was initially characterized as a serine/threonine kinase, might in fact have dual specificity. This hypothesis is strengthened by the observation thatEscherichia coli induced to express F10 contain multiple proteins which are recognized by antiphosphotyrosine antiserum. This study presents the first evidence for phosphotyrosine signaling during vaccinia virus infection and implicates the F10 kinase and the H1 phosphatase as the dual-specificity enzymes that direct this cycle of reversible phosphorylation.