Rapid detection and quantitation of human cytomegalovirus in urine through DNA hybridization

Early detection of cytomegalovirus in cell culture by a monoclonal antibody

A commercially available monoclonal antibody directed against early cytomegalovirus (CMV) antigen was used for the demonstration of CMV by immunofluorescence (IF) in cell culture within 2 days. The results were compared with the appearance of CMV-specific cytopathogenic effect (CPE). Urine specimens from 31 healthy children in day-care centers were inoculated on human embryonic fibroblasts. In addition, 45 CMV strains that had been stored at -70 degrees C were reinoculated. CMV was detected in 8/31 urine specimens by IF and 7 of these gave a specific CPE at an average of 16 days post-inoculation. One specimen was negative by IF but specific CPE was found at day 13. After reinoculation, CMV was detected in 76% by IF while 44 specimens developed CPE within a 6-week period. Demonstration of early CMV antigen in cell culture was found to be a rapid method for early diagnosis of CMV. Since the conventional cell culture with detection of CPE was more sensitive it may be useful to combine the two methods.

Infection in renal transplant recipients. Current approaches to diagnosis, therapy, and prevention

Despite dramatic improvements in patient and renal allograft survival, infections continue to be an important cause of post-transplantation morbidity and mortality. Most serious infections manifest clinically as febrile diseases, and immunosuppression-induced compromised cell-mediated immunity is the basis for the predominance of infections due to opportunistic intracellular microorganisms. Diagnostic evaluation is guided by the timing of fever after transplantation, epidemiologic factors, and evidence of specific organ system involvement. Although current therapy of bacterial and parasitic infections is usually effective, the management of deep-seated fungal infections remains highly unsatisfactory. Cytomegalovirus disease, the single most important infection in some transplant centers, frequently presents as a self-limited viral syndrome; however, multiple organs may be affected. New measures for the rapid diagnosis and treatment of this viral infection hold promise. A number of recommendations have been proposed to prevent infections in renal transplant recipients; however, continued progress will depend primarily upon further refinements in immunosuppressive therapy.

The vector homology problem in diagnostic nucleic acid hybridization of clinical specimens

Nucleic acid hybridization techniques using cloned probes are finding application in assays of clinical specimens in research and diagnostic laboratories. The probes that we and others have used are recombinant plasmids composed of viral inserts and bacterial plasmid vectors such as pBR322. We suspected that there was material homologous to pBR322 present in many clinical samples. because hybridization occurred in samples which lacked evidence of virus by other techniques. If the presence of this vector-homologous material was unrecognized, hybridization in the test sample might erroneously be interpreted as indicating the presence of viral sequences. In this paper we demonstrate specific hybridization of labeled pBR322 DNA with DNA from various clinical samples. Evidence is presented that nonspecific probe trapping could not account for this phenomenon. In mixing experiments, it is shown that contamination of clinical samples with bacteria would explain such a result. Approaches tested to circumvent this problem included the use of isolated insert probes, alternate cloning vectors, and cold competitor pBR322 DNA in prehybridization and hybridization mixes. None proved entirely satisfactory. We therefore emphasize that it is essential that all hybridization detection systems use a control probe of the vector alone in order to demonstrate the absence of material with vector homology in the specimen tested.

Clinical applications of gene probes in human genetic disease, malignancy, and infectious disease

Recent developments in recombinant DNA technology have made possible the production of gene probes consisting of cloned gene segments, cloned segments of DNA linked to genes, and synthetic gene fragments. Several methods have been developed by which these probes may be used for the diagnosis of human disease. This technology has been outstandingly successful for prenatal diagnosis and carrier detection in many genetic diseases. These methods have also been successfully applied to the analysis of human malignancies, by providing for the determination of cell lineage and clonality in lymphoid neoplasms. Finally, these methods have shown potential for rapid and sensitive diagnosis of some infectious diseases.

In situ hybridization for the detection of cytomegalovirus (CMV) infection. Application of biotinylated CMV-DNA probes on paraffin-embedded specimens

Five autopsy cases of cytomegalovirus (CMV) infections were studied. Conventional light microscopy disclosed characteristic cytopathic effects in lungs, kidneys, and brain. In one case, electron microscopy was carried out and revealed typical herpesvirus particles. In situ hybridization was done with biotin-labeled CMV-DNA probes and an avidin-alkaline phosphatase detection system. 4/5 cases were observed to contain hybridizing cells in different organs. Intensity of hybridization was related to the severity of CMV infection, roughly estimated by counting cytomegalic cells. In addition to cytomegalic cells, a high number of normal-looking epithelial and mesenchymal cell types were positive. These latter cells showed nuclear hybridizations in contrast to cytomegalic cells which hybridized both within the nuclei and the cell bodies. This modified in situ hybridization procedure is a rapid and valuable tool for the detection and final demonstration of virus infection, and will be of particular help for the examination of paraffin-embedded specimens.

Use of a molecular probe for detecting JCV DNA directly in human brain material

A hybridot assay using a radiolabelled JC virus probe has been used to detect the presence of JCV DNA in brain biopsy and postmortem brain samples from patients with neurological disease and possible progressive multifocal leucoencephalopathy. Sixty-nine brain samples from 45 patients were examined. Eleven samples from eight patients had detectable JCV DNA sequences. In seven of the eight patients this result was confirmed by electron microscopy and/or virus isolation or immunofluorescence.

Rapid diagnosis of cytomegalovirus infection

Several assays are in preparation for the diagnosis of cytomegalovirus infection in acquired immune deficiency syndrome and other immunocompromised patients. In particular, ELISA and DNA probes look to be particularly promising for testing body fluids and tissue sections respectively but these assays are not currently available. The technique of detection of early fluorescent antigen foci (DEAFF) has for some time been available as a diagnostic service to immunocompromised patients served by the author's laboratory. Although it requires cell culture and immunofluorescent techniques it is capable of detecting most patients with productive infection. In particular, the rapid availability of results has allowed patients to be entered into trials of new antiviral agents.

A non-radioactive DNA probe to identify Shigella and enteroinvasive Escherichia coli in stools of children with diarrhoea

A non-radioactive biotinylated DNA probe was constructed to detect Shigella and enteroinvasive Escherichia coli (EIEC). Specimens were examined with the biotinylated probe after removing streptavidin-binding glycoproteins with proteinase K. Both biotinylated and radioactive probes detected 125 pg of target-cell DNA after hybridisation for 24 h and exposure to indicator dyes or X-ray film for 4 h. Both probes hybridised with 52 EIEC and none of 16 non-EIEC examined; they also hybridised with stool blots from 11 of 13 children with culture-proven shigellosis or EIEC diarrhoea and were negative with stool blots from 43 children who were culture negative for Shigella and EIEC. Biotinylated DNA probes can be as sensitive as radiolabelled probes, but have the advantage of a longer shelf-life and greater availability.

Detection of human polyomavirus DNA in urine specimens by hybridot assay

A hybridot assay method using a labelled BK virus probe has been used to detect the presence of human polyomavirus DNA in 81 urine specimens from 61 patients, most of whom were immuno-compromised to some degree. Twenty-eight urines from 23 patients had detectable DNA. The results have been compared to virus isolation and electron microscopy on the same specimens. In 90 per cent a comparable result was obtained by at least one of the other two tests and in the 73 specimens on which all 3 tests were performed there was 80 per cent agreement between all. In 6 cases the hybridot assay was more sensitive in detecting infection.

Monoclonal antibody for rapid laboratory detection of cytomegalovirus infections: characterization and diagnostic application

Monoclonal antibodies to early (2H2.4, molecular weight 72,000 daltons) and late (2F3.0, molecular weight 68,000 daltons) antigens of the AD-169 strain of cytomegalovirus (CMV) were prepared by fusing mouse spleen cells with NS-1 mouse myeloma cells. The 2H2.4 monoclonal antibody produced a dense immunofluorescence with prominent lobular staining within the nucleus of CMV-infected substrate cells, whereas the reaction of 2F3.0 was more diffuse and generally involved the entire nucleus of the cells. Both monoclonal antibodies had little or no neutralizing activity against CMV in plaque-reduction assays. No cross-reactions were observed between these monoclonal antibodies and other members of the herpesvirus group. The 2H2.4 monoclonal antibody to early CMV antigen was used in a shell vial assay with a low-speed centrifugation step for the rapid (within 16 hours after inoculation) diagnosis of CMV infections. Optimal conditions for the test included centrifugation of shell vials at 700 X g for 45 minutes at 36 degrees C. An inoculum volume of 0.2 ml provided a reasonable balance between the optimal sensitivity for detecting specific viral fluorescence and the easy discrimination of the specific immunofluorescence from the background debris. Because of the commercial availability of the monoclonal antibody and the simplicity of the procedures used in the shell vial assay and subsequent fluorescence techniques, this rapid assay can be done in any laboratory that is familiar with cell culture manipulations.

Detection of cytomegalovirus by DNA-DNA hybridization employing probes labelled with 32-phosphorus or biotin

Various factors influencing the detection of human cytomegalovirus (HCMV) in infected cells by DNA-DNA hybridization have been investigated. Employing the Hind III O fragment of HCMV AD169 labelled with 32P, we found that detection sensitivity was highly influenced by the method employed for extraction of DNA from infected cells. Excision of the Hind III O fragment from the vector by restriction endonuclease digestion prior to 32P-labelling further improved the detection capability of the probe. Similarly, cytomegalovirus (CMV) DNA detection employing biotin-labelled probes and streptavidin/alkaline phosphatase in the hybridot assay was also highly dependent on the method of DNA extraction prior to hybridization. Finally, we describe an in situ assay employing a biotin-labelled probe and fluorescein-conjugated avidin to detect CMV DNA in cultured cells.

Respiratory tract infections. Goals for 1995

Goals to be identified for 1995, a decade hence, in the prevention, diagnosis, and management of respiratory tract infections may conveniently be divided into diagnostic goals and goals in therapy and prophylaxis. Major diagnostic goals for bacterial, viral, and mycoplasmal infections of the respiratory tract focus on the development of systems to identify microbial components, such as specific antigens or segments of DNA, using monoclonal antibody techniques or DNA probes for hybridization. Sputum cultures, in the traditional sense, should ultimately become obsolete. Management goals include the development of algorithms to identify patients who should be hospitalized, in contrast to those who can safely be treated on an outpatient basis. New antibiotic drug development should include drugs active against methicillin-resistant staphylococci, broad-spectrum beta-lactam drugs that are orally active against gram-negative bacilli, and drugs that can be used parenterally on a once-daily basis in settings other than the acute care hospital. There are certainly needs to enhance the present spectrum of antiviral drugs and to develop therapeutically useful immunomodulators. There are promising prospects for vaccine development, including live attenuated influenza virus vaccine, parainfluenza virus vaccine, respiratory syncytial virus vaccine, and a Mycoplasma pneumoniae vaccine. With major research support, such vaccines could possibly be fully developed by 1995. Finally, of greatest importance is the need to achieve greater utilization of existing vaccines, that is, inactivated influenza vaccine and the current 23-valent pneumococcal vaccine. A legitimate goal for 1995 would be to achieve 70 percent or greater utilization of these vaccines within the recommended target populations.

Detection of adenovirus in nasopharyngeal specimens by radioactive and nonradioactive DNA probes

The presence of adenovirus DNA in clinical specimens was analyzed by nucleic acid hybridization assays by both radioactive and enzymatic detection systems. The sensitivity of the hybridization tests was in the range of 10 to 100 pg of homologous adenovirus DNA. Minimal background was noticed with unrelated viral and nonviral DNA. Twenty-four nasopharyngeal mucus aspirate specimens, collected from children with acute respiratory infection, were assayed in the hybridization tests and also by an enzyme immunoassay for adenovirus hexon antigen which was used as a reference test. Sixteen specimens positive by the enzyme immunoassay also were positive in the two nucleic acid hybridization tests, and the remaining eight specimens were negative in all of the tests. The results indicate that nucleid acid hybridization tests with both radioactive and nonradioactive probes can be used for diagnosis of microbial infections.

Direct detection of the human papovavirus BK in urine of bone marrow transplant recipients: comparison of DNA hybridization with ELISA

Urine specimens from bone marrow transplant (BMT) recipients and from controls were directly tested for BK virus (BKV) DNA sequences by dot hybridization and for BKV antigen by a double-antibody indirect ELISA. A total of 158 specimens from 55 BMT patients (57 collected prior to or at the time of transplantation and 101 in the posttransplant period) and single urines from 125 control subjects were examined by both methods. A molecularly cloned, 32P-labelled BKV probe was hybridized with urine sediments that were spotted directly on nitrocellulose filters and denatured in situ. BKV DNA sequences were detected in 1 (1.8%) pretransplant and 22 (21.8%) posttransplant urines of BMT patients, and in none of control urines. In ELISA of urine supernatants, BKV antigen was detected in 1 (1.8%) pretransplant and 21 (20.8%) posttransplant urines of BMT patients and in 1 (0.8%) of the control urines. The results of the two tests correlated as follows: 16 urines were positive and 253 urines negative by both methods; seven specimens were positive by DNA hybridization only and seven were positive by ELISA alone. Virus excretion in urine was demonstrated in 20 (36.4%) patients by DNA hybridization, in 19 (34.5%) patients by ELISA, in 15 (27.3%) patients by both methods, and in 24 (44%) patients by at least one of the two tests.

Rapid detection of cytomegalovirus in cell culture by indirect immunoperoxidase staining with monoclonal antibody to an early nuclear antigen

A method for the rapid detection of cytomegalovirus (CMV) in MRC-5 cells 48 h after inoculation with clinical specimens was developed. A commercially available monoclonal antibody to a CMV early nuclear antigen was used in an indirect immunoperoxidase (IPA) staining procedure performed directly on acetone-fixed cell monolayers in standard tubes (16 by 125 mm). Of 190 clinical specimens tested, 30 specimens produced CMV cytopathic effect in tissue culture (TC-CPE) within 14 days after inoculation and, of these 30, 28 were positive for CMV after 48 h by the IPA staining procedure (sensitivity, 93%). Of the remaining 160 clinical specimens negative by TC-CPE within 14 days, 7 were positive by the IPA stain (specificity, 96%). However, three of these seven specimens were positive by TC-CPE upon subculture after the initial 14-day incubation period, and one specimen was overgrown by herpes simplex virus type 2 before CMV cytopathic effect could develop. The mean time to appearance of cytopathic effect for the 30 specimens positive by TC-CPE within 14 days was 6.7 days. These findings indicate that this IPA staining is a useful method for the rapid detection of CMV in cell monolayers inoculated with clinical specimens.

Human cytomegalovirus infection: recent developments in diagnosis and epidemiology

Cytomegalic inclusion disease (CID) is caused by a horizontally or vertically transmitted human herpes virus infection and may persist for life without obvious clinical symptoms. A serious course of horizontal primary and recurrent infections, however, is often observed in immunocompromised persons such as recipients of organ transplants and patients receiving fresh blood transfusions. Vertical infection may cause fetopathies. The human cytomegalovirus (HCMV) is thought to inherit an oncogenic potential as lately discussed for AIDS and M. Kaposi. Laboratory diagnosis of HCMV infection is performed by light microscopy (inclusion bodies), electron microscopy, virus isolation in cell culture, demonstration of viral DNA and antigen in clinical specimens, by histochemical methods (e.g. immunoperoxidase technique) and by DNA and peptide analysis for identification of different isolates and viral finger prints. Evaluation of cell-mediated immunity in HCMV infection is performed quantitatively (assessment of Thelper/Tsuppressor ratios) or qualitatively (specific lymphocyte stimulation by the antigen). In most cases laboratory diagnosis is achieved by serological methods, i.e. demonstration and quantitation of HCMV-specific antibodies. In this context, a number of liquid- and solid-phase immunoassays have been developed, of which immunofluorescence and ELISA are most commonly used, besides complement fixation and passive haemagglutination. These procedures on the one hand allow the use of different antigen preparations as early and late viral proteins, and on the other hand permit a specific determination of different Ig classes and subclasses. A variety of assays has been established especially for determination of virus-specific IgM antibodies, which are predominantly found in active infection. These, however, at least in part may show non-specific results caused by interference of rheumatoid factor or IgG competition. Such problems have now been dealt with and are avoided by IgG precipitation or IgM immunosorption ("mu-capture" technique). These recent methods allow an exact epidemiological identification of risk groups for CMV infection. Results from our laboratory revealed 13% HCMV-IgM positive patients among pregnant women, 16% IgM positive patients among renal transplant recipients, 4% IgM positive cases in patients after cardiosurgery and 1.7% IgM positives among prostitutes. The prevalence of HCMV infection as indicated by specific IgG antibodies was 56%, 90%, 83%, and 90%, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Nucleic acid probes in diagnosis of viral diseases of man. Brief review

With the recent, rapid advances in recombinant DNA technology, it has become possible to consider the use of nucleic acid probes in diagnosis of human viral diseases. Several examples are discussed which employ techniques of dot blot hybridization, sandwich hybridization and in situ hybridization. Typing of viral strains using restriction endonuclease digestion as an epidemiological tool is considered. Finally, the present limitations of molecular hybridization are discussed, and future developments including the production of non-radioactively labeled probes, are assessed.

Detection of Epstein-Barr virus DNA in mouthwashes by hybridization

An assay for the presence of Epstein-Barr virus (EBV) DNA was developed by using a cloned EBV DNA probe. After preliminary testing showed the assay to be sensitive and specific, it was applied to 135 mouthwashes from bone marrow transplant recipients, and 21 of these tests were positive. The concentration of EBV DNA in mouthwashes in some cases was as high as 10(8) genome equivalents per ml. When compared with the lymphocyte transformation assay on the same samples, the sensitivity was 75% and the specificity was 97%. In contrast to the lymphocyte transformation assay, the hybridization was semiquantitative and yielded results in 72 h. Potential applications include monitoring the effects of various interventions, such as immunosuppressive and antiviral chemotherapy, on EBV shedding.

Detection of human parvovirus using a molecularly cloned probe

Half of the genomic DNA of the human parvovirus (B19) was cloned in the plasmid pBR322. The cloned DNA was used as a molecular probe for the detection of parvovirus in serum by means of a dot hybridization test. In an assay of 26 samples, the dot hybridization test was found to be of comparable sensitivity and to be as rapid as radioimmunoassay for viral antigen detection; it is potentially useful as a diagnostic test.

Comparison of standard tube and shell vial cell culture techniques for the detection of cytomegalovirus in clinical specimens

A monoclonal antibody was used to detect an early antigen of cytomegalovirus (CMV) by fluorescence 16 h after inoculation of MRC-5 monolayers in 1-dram (ca. 3.7-ml) shell vials and low-speed centrifugation. Of 770 specimens (urine, blood, lung tissue, sputum) processed in shell vials, 124 (16%) were positive for the virus at 16 h postinfection. CMV was isolated in standard tube cell cultures (average time, 9 days) from only 88 specimens, but there were no instances (with the exception of 2 blood specimens) in which CMV was recovered from tube cultures but not from shell vials. Additional specimens from 18 patients were positive in the shell vial assay but negative in the conventional tube cell culture assay. Other specimens from 14 of the 18 patients yielded CMV in conventional tube cell cultures. Of the 4 patients from whom CMV was not recovered from other specimens by conventional tube cell culturing, all had evidence of recent CMV infections, as indicated by a fourfold or greater rise in antibody titer. The specificity of the shell vial assay for the detection of CMV is supported by assays of other specimens from the same patients yielding the virus or serological evidence indicating recent infections, the known enhancement of CMV detection after centrifugation of the shell vials, and the distinct and easily recognizable fluorescence confined to the nuclei of CMV-infected cells. Our data indicate that the shell vial cell culture assay for the detection of CMV is as specific as and more sensitive than conventional tube cell culturing for the diagnosis of CMV infections.

Cytomegalovirus in urine: detection of viral DNA by sandwich hybridization

A cytomegalovirus (CMV)-specific sandwich hybridization test was constructed by using two adjacent BamHI DNA fragments of CMV DNA as reagents. The fragments were cloned into two different vectors. One of the recombinants was attached to the filter, and the other was the labeled probe. When present in the sample, CMV DNA mediated labeling of the filter by hybridizing to both the filter-bound DNA and the probe. The sandwich hybridization test was applied for the detection of CMV DNA from urine. DNA was released from virus by 2% Sarkosyl, concentrated by 2-butanol extraction and isopropanol precipitation, denatured, and finally subjected to the sandwich hybridization test. As a result, 70 to 90% of the original viral DNA could be recovered and demonstrated by the quantitative hybridization reaction. Urine could be stored at room temperature in Sarkosyl for at least 2 days without affecting the detectability of CMV. The clinical applicability of the test was evaluated by studying urine samples from four infants excreting CMV. Sandwich hybridization demonstrated the presence of CMV DNA in all of the specimens. These contained originally 10(5) to 10(8) CMV DNA molecules per ml.

Inhibition of human cytomegalovirus replication by 9-(1,3-dihydroxy-2-propoxymethyl)guanine alone and in combination with human interferons

The inhibitory action of 9-(1,3-dihydroxy-2-propoxymethyl)guanine on the replication of human cytomegalovirus was studied. Three laboratory strains (AD-169, Towne, and Davis) and three early passage (less than 10) clinical isolates were all inhibited in yield inhibition assays. In cultures infected with AD-169, virus yields could be inhibited if the drug was added as late as 3 days after the replication cycle had begun. The effects of the drug were fully reversible during the first 4 days of the viral replication cycle. Viral infectivity and viral DNA synthesis were reduced more than viral protein synthesis. Synergistic antiviral effects were observed with beta-cysteine, and to a lesser extent, with beta-serine recombinant interferons, but only over a narrow range of dose combinations.

Characterization of trimethoprim resistance by use of probes specific for transposon Tn7

Transposon Tn7 codes for resistance to trimethoprim and streptomycin. For detection of Tn7 by DNA-DNA hybridization, two recombinant plasmids were constructed. The former contained a 1-kilobase BamHI fragment and the latter contained a 4.3-kilobase EcoRI-BamHI fragment of Tn7. These DNA fragments, which did not include the drug resistance genes, were used as probes for detecting Tn7-like sequences in bacterial strains by colony hybridization. They hybridized strongly to bacterial DNA known to carry Tn7 but not to DNA known to carry transposons other than Tn7. These probes were used to study the occurrence of Tn7 in bacterial strains isolated in the Turku City Hospital in Finland. Transposon Tn7 was present in 47.2% of 199 trimethoprim-resistant enterobacteria (MIC greater than or equal to 8 micrograms/ml). Among the 69 Proteus mirabilis strains studied, 75% contained Tn7, although none of these strains transferred trimethoprim resistance in conjugation tests. The reliability of colony hybridization was further confirmed by Southern hybridization to detect the Tn7-specific 2.6-kilobase HindIII restriction fragment. Colony hybridization proved to be a sensitive and rapid method for detecting Tn7-determined sequences.

Rapid detection of cytomegalovirus in MRC-5 cells inoculated with urine specimens by using low-speed centrifugation and monoclonal antibody to an early antigen

A commercially available monoclonal antibody directed against an early nuclear protein of cytomegalovirus was used with low-speed centrifugation for the rapid detection of this virus from urine specimens inoculated onto MRC-5 cells. A total of 19 of 162 (11.7%) urine specimens inoculated were positive by both immunofluorescence and peroxidase-antiperoxidase procedures (sensitivity, 100%), whereas only 18 of the samples produced cytopathic effects in conventional cell culture (specificity, 94.7%). All specimens were positive by immunofluorescence and peroxidase-antiperoxidase procedures at 36 h postinfection, whereas an average of 9 days was required for cytopathic effects to develop in cell cultures.

Detection of enteroviruses by spot hybridization

A cloned partial cDNA copy of the coxsackievirus B3 genome was used for detecting enteroviruses in infected cells by employing a nucleic acid hybridization procedure. Cells infected with coxsackieviruses A and B, echovirus, and poliovirus gave positive hybridization signals, whereas cells infected with nonrelated viruses did not.

Herpes virus infections in patients with neoplastic disease. Diagnosis and therapy

Herpes viruses are among the most common and troublesome opportunistic pathogens infecting patients with neoplastic diseases. The recent development of partially effective and relatively nontoxic antiviral agents offers promise for the prophylaxis or therapy of these infections in high-risk groups. Vidarabine and acyclovir have shown efficacy in several herpes virus infections and are now licensed in the United States. Alpha interferon may also be useful in the prophylaxis or early therapy of certain herpes virus infections. Newer antiviral agents and combination therapies are under study. Early and rapid diagnosis of such infections is critical to the development of effective therapy.

Alpha-interferon administration in cytomegalovirus retinitis

Four patients, including three with the acquired immunodeficiency syndrome (AIDS), were treated with high-dose, buffy coat-derived alpha-interferon for progressive cytomegalovirus retinitis. Two of these patients had decreased viruria during therapy and the other two had increased viruria. There was evidence of progression of disease despite therapy in all patients, although the retinitis eventually became quiescent in the patient without AIDS. The severe immunosuppression encountered in AIDS patients complicates the management of cytomegalovirus and other opportunistic infections.

DNA of 21 clinical cytomegalovirus strains detected by hybridization to cloned DNA fragments of laboratory strain AD-169

Nine distinct DNA probes prepared from cloned DNA fragments of the cytomegalovirus (CMV) strain AD-169, each representing a relatively small portion of the total genome, were able to detect all 21 epidemiologically distinct clinical isolates of CMV that had been passaged in tissue culture. All probes were of comparable sensitivity in the detection of CMV, and under the hybridization conditions used, no probe gave an unusually high background with uninfected host cells.

DNA-DNA hybridization assay for detection of Salmonella spp. in foods

We have developed a DNA-DNA hybridization test for the presence of Salmonella spp. in foods. This test requires an initial pre-enrichment of food samples in nutrient broth but does not require selective enrichment. Samples of food cultures are collected on membrane filters and assayed by molecular hybridization to labeled probes. The probes consist of DNA sequences which are unique to the genus Salmonella and are widely distributed in the genus. A diverse panel of foods was assayed successfully by this methodology.

Antiviral drugs 1983

A number of antiviral compounds are currently available, and several others are of great interest. Trifluridine, idoxuridine, and vidarabine are effective topically in herpes simplex virus keratoconjunctivitis infection. Vidarabine (and presumably acyclovir) is effective in herpes simplex virus encephalitis and in herpes zoster infections in the immunocompromised host. Acyclovir is effective topically, orally, and intravenously in primary herpes genitalis, and the oral and intravenous forms are effective in recurrent herpes genitalis as well. Amantadine and rimantadine are effective prophylactically and therapeutically in influenza A infections. Ribavirin and interferon, although not licensed, are of great interest. Ribavirin may be useful in respiratory syncytial virus infections, and interferon may be of benefit in common colds and related disorders.