Rapid detection of cytomegalovirus in clinical specimens by using biotinylated DNA probes and analysis of cross-reactivity with herpes simplex virus

Overview of the diagnosis of cytomegalovirus infection

Cytomegalovirus (CMV) is recognized as the most common congenital viral infection in humans and an important cause of morbidity and mortality in immunocompromised hosts. This recognition of the clinical importance of invasive CMV disease in the setting of immunodeficiency and in children with congenital CMV infection has led to the development of new diagnostic procedures for the rapid identification of CMV. Diagnosis of acute maternal CMV infection by the presence of immunoglobulin (Ig)M and low-avidity IgG requires confirmation of fetal infection, which is typically performed using polymerase chain reaction (PCR) assays for CMV on amniotic fluid. Viral culture of the urine and saliva obtained within the first two weeks of life continues to be the gold standard for diagnosis of congenitally-infected infants. PCR assays of dried blood spots from newborns have been shown to lack sufficient sensitivity for the identification of most neonates with congenital CMV infection for universal screening purposes. However, saliva PCR assays are currently being assessed as a useful screening method for congenital CMV infection. In the immunocompromised host, newer rapid diagnostic assays, such as phosphoprotein 65 antigenemia and CMV real-time PCR of blood or plasma have allowed for preemptive treatment, reducing morbidity and mortality. However, lack of standardized real-time PCR protocols hinders the comparison of data from different centers and the development of uniform guidelines for the management of invasive CMV infections in immunocompromised individuals.

Congenital cytomegalovirus infection: outcome and diagnosis

Cytomegalovirus (CMV) is the most common congenital infection in humans and an important cause of morbidity and mortality in immunocompromised hosts. Congenital CMV infection occurs in approximately 0.5 to 1 percent of all newborns in the United States and can result in significant neurological sequelae. The gold standard for diagnosing congenital CMV infection is isolation of the virus from infants within the first 2 weeks of life through conventional or rapid cell culture techniques. Newer molecular diagnostic methods to diagnose congenital CMV infection, including the nucleic acid amplification of viral DNA from the peripheral blood of infants, are being investigated, and the preliminary results show promise. However, more work must be done to standardize and validate these methods before they can be used routinely in establishing the diagnosis of congenital CMV infection.

A highly sensitive nonisotopic detection method for in situ hybridization

In situ hybridization is a technique that allows detection of specific DNA and RNA sequences in tissue sections. Nonisotopic techniques are fast and give a precise localization of the hybridization product, but a drawback is the low sensitivity. However, the sensitivity is dependent on the detection system used. To evaluate a sensitive in situ hybridization method with nonradioactive probes we compared three different detection systems, using biotin-labeled human papillomavirus (HPV) 16 probes. The three detection systems included (i) STAV-FITC method (streptavidin-fluorescein isothiocyanate/alkaline phosphatase anti-FITC), (ii) APAAP method (mouse anti-biotin/anti-mouse IgG/alkaline phosphatase mouse anti-alkaline phosphatase), and (iii) tyramide signal amplification (TSA) method (STAV-horseradish peroxidase (HRP)/biotinyl tyramide/STAV-HRP). The in situ hybridization methods were tested on CaSki and SiHa cells and two cervical carcinomas known to be HPV16 positive. The cells and tissues and been fixed in 4% buffered formalin and paraffin embedded. The three different detection systems gave satisfactory nuclear staining in CaSki cells (CaSki cells contain > 500 copies of HPV16 DNA) and the two cervical carcinomas. However, demonstration of HPV16 DNA in SiHa cells (SiHa cells contain one to two HPV16 genome copies) was possible only by use of the APAAP method. It was concluded that the APAAP method provides the best sensitivity among the nonisotopic detection systems and can detect single viral copies in formalin-fixed and paraffin-embedded material.

Recurrent aphthous ulceration: a possible clinical manifestation of reactivation of varicella zoster or cytomegalovirus infection

The etiology of the most common intraoral mucosal disease, recurrent aphthous ulceration (RAU), remains obscure. Here, attempts were made to diagnose reactivation of varicella zoster (VZV), cytomegalovirus (CMV), Epstein-Barr (EBV) and human hepes virus 6 (HHV-6) infections from paired sera in association with RAU recurrences. The first sample was obtained within 3 days after a new recurrence (1) and the second 10-14 days later (2). The study initially comprised 18 otherwise healthy RAU patients (gr A) and 17 sex- and age-matched healthy non-RAU individuals. Values of specific antibody subclasses (IgM, IgG, IgA) were determined by ELISA (VZV, CMV, EBV) and IFA (HHV-6). Patients and controls exhibited differences in parameters on specific VZV IgM and CMV IgM. In order to substantiate these findings, specific VZV IgM and CMV IgM were subsequently also evaluated in 17 other RAU patients (gr B). Ten patients in gr A and 11 in gr B were IgM seropositive for either VZV and/or CMV in at least one of the serum samples, whereas in the controls only one was VZV IgM positive and none CMV IgM positive. Evaluated as groups, optometric density (OD) antibody levels of VZV IgM were significantly higher in the patients (gr A (1,2) vs controls: p < 0.0001; gr B (1,2) vs controls: p < 0.001). CMV OD IgM antibody values were significantly higher in gr B only (1,2 vs controls: p < 0.01). The study lends support for reactivation of VZV and/or CMV infection associated with RAU recurrences.

Comparison of immunocytochemistry and in situ hybridization in the cytodiagnosis of genital herpetic infection

Over a 62-month period, 53 patients were found to have cervicovaginal smears that contained cells consistent with, or equivocal cells for, a herpes simplex virus (HSV) infection. The Papanicolaou-destained smears from these cases were restrained in situ hybridization (ISH) with a biotinylated cloned DNA probe and immunocytochemistry (ICC) assay and were compared for the detection of HSV in cervicovaginal smears by two methods. Cytological findings classified the 53 slides into two groups, i.e., cytologically herpes positive (33 patients) and equivocal cases (20 patients). Each group was subdivided into two groups: group A was confirmed by ICC, and group B was confirmed by ISH technique. Of the 33 cellular samples containing cells considered to be consistent with a herpes infection, 15 (88%) of 17 were positive by means of ICC technique (group A), 6 (43%) of 14 were positive by ISH technique (group B). Of the 20 smears showing equivocal cell changes thought unlikely to be caused by an HSV infection, 6 (60%) of 10 were positive by ICC (group A), 2 (29%) of 7 were positive by ISH (group B). With the ISH technique, five smears showed dislodged cells from glass slides due to enzyme treatment and denaturation. The results revealed that the ICC technique is a rapid and reliable procedure and thus recommended for routine diagnosis of HSV infection. Moreover, ICC is easier to perform and interpret and is less expensive than ISH. Therefore, the ICC may be preferable to ISH for detecting HSV in routine Papanicolaou diagnostic work.

Nucleic acid hybridization in viral diagnosis

Since 1982, numerous studies have been published utilizing a variety of hybridization techniques to detect viral nucleic acid directly in clinical specimens and in tissue sections. However, hybridization techniques are still not widely used in the clinical laboratory. Other recent advances, such as the development of monoclonal antibodies for virus identification and ELISA kits for virus detection, and the introduction of centrifugation cultures for rapid diagnosis, have postponed the clinical application of hybridization techniques. Furthermore, the use of hybridization for diagnosis has been limited by its insensitivity when compared to cell culture, the need for radioisotopes to increase sensitivity, and the difficulties inherent in transferring a basic research tool to the clinical laboratory. Nevertheless, with recently developed amplification techniques and further advances in nonradioactive labelling of probes, it can be expected that nucleic acid hybridization will be an established technique in diagnostic laboratories in the near future.

The value of immunohistochemistry and in situ hybridization in detecting cytomegalovirus in bone marrow transplant recipients

Autopsy tissues of 19 patients with complications after bone marrow transplantation (BMT) were analysed for the presence of cytomegalovirus (CMV) using histochemical methods. CMV antigens were detected by antibodies to CMV Immediate Early Antigen (IEA) or CMV Late Antigen (LA). CMV-DNA was detected by DNA in situ hybridization (DISH). IEA was detected in one or more tissues in 79% of 14 patients from whom frozen tissue was available. CMV-DNA was detected on paraffin sections in 84% of all 19 patients. CMV components were present in all organs studied; the highest incidence was found in lung, gastrointestinal tract and kidney. In histology, only 37% of patients showed signs of CMV infection by the presence of cytomegalic cells with nuclear inclusions (or so called "owl eye cells"). In tissue culture, only 33% of 15 patients were CMV positive. Serologically, 68% of all patients had active CMV infection, as indicated by a rise in antibody titres. We conclude that the quick detection of CMV IEA and CMV-DNA has a high sensitivity and predictive value, which is comparable to or exceeds the serological detection of CMV.

Direct detection of human cytomegalovirus in urine specimens from renal transplant patients following polymerase chain reaction amplification

A polymerase chain reaction (PCR) assay was used to amplify human cytomegalovirus (HCMV) directly from urine specimens taken from renal transplant patients. In serial urine samples from patients who had at least one specimen positive for HCMV; the PCR assay consistently detected the presence of HCMV DNA sequences, whereas virus detection by other tests such as enzyme-linked immunosorbent assay (ELISA), nonradioactive DNA hybridization assay, and virus isolation were variable. Of 37 specimens positive by PCR, 36 were positive by either ELISA, hybridization assay, or virus isolation. Infectious virus was detected in 13 of the 37 PCR-positive urines. HCMV DNA was detected by PCR in all samples that were positive for HCMV by either hybridization assay or virus isolation. The viral genome copy number was determined by PCR assay for several urine samples that were positive by virus isolation but negative for HCMV by ELISA or hybridization assay. Viral genome copy number estimates indicated the presence of HCMV at very low levels in these urines verifying the fidelity of the virus isolation procedures. The consistency of the PCR assay makes it an ideal method for detection of infection and monitoring antiviral drug therapy in patients infected with HCMV.

Cytomegalovirus retinitis

Cytomegalovirus retinitis is a frequent and serious complication of various conditions, including diseases characterized by impaired immunity, such as the acquired immunodeficiency syndrome. Due to recent advances in the treatment of cytomegalovirus retinitis, accurate diagnosis and management have become increasingly important. In this review, the authors present the epidemiology, clinical features, diagnostic testing, treatment with complications, and prognosis of cytomegalovirus retinitis. A differential diagnosis is presented and the characteristic ocular lesions are illustrated.

Detection of human cytomegalovirus DNA in liver biopsies from patients with cytomegalovirus-related liver disease

Infection with human cytomegalovirus (HCMV) has been associated with severe diseases in immunologically impaired patients. Cytomegalovirus hepatitis has been frequently described in this population, but this diagnosis is still difficult. Molecular hybridization with the V EcoRI restriction fragment of human cytomegalovirus strain AD 169 has been tested upon DNA extracted from liver samples to assess the usefulness of this technique for cytomegalovirus hepatitis diagnosis. This probe was shown by the Southern technique not to hybridize with DNA extracted from cells infected with other herpesviruses or with DNA of non-infected normal liver. The sensitivity was estimated to be 2 x 10(5) genomes. Twenty-five renal transplant recipients under immunosuppressive therapy and three patients having the acquired immunodeficiency syndrome were studied. In 9 out of 10 renal transplant recipients with normal liver, previous exposure to cytomegalovirus, as defined by serological tests, was not sufficient to allow positive detection by the probe. Out of 11 patients with abnormal liver, cytomegalovirus DNA sequences were shown in 5. In 2 patients with histological evidence of cytomegalovirus hepatitis, a very strong signal showed the presence of viral genomes. These results show that the Southern technique with the V EcoRI probe can be useful for the diagnosis of HCMV hepatitis and might be proposed for the detection of this viral genome in human tissues.

Detection of cytomegalovirus DNA using probes labelled with digoxigenin

Cloned HindIII restriction fragments of cytomegalovirus (CMV) DNA (strain AD169) were labelled with biotin, digoxigenin or 32P and used as probes to detect CMV DNA. Probes biotinylated by nick translation, random hexanucleotide priming (RHP) or "photobiotin" were able to detect 10-50 pg of homologous DNA. Probes labelled with digoxigenin or 32P by RHP detected 0.1 pg of homologous DNA, and 1-10 CMV-infected fibroblasts. Comparison of digoxigenin- and 32P-labelled probes in a DNA hybridisation assay on 186 urine specimens demonstrated that these probes were of similar sensitivity, detecting CMV DNA in 40 and 41 specimens, respectively. Positive results were obtained using this hybridisation assay with 11 of 14 specimens (79%) yielding CMV by virus isolation, and with 35 other specimens obtained from patients with laboratory evidence of CMV infection or symptoms compatible with CMV disease. Thus digoxigenin-labelled probes may provide an assay that can detect CMV DNA in specimens yielding a negative result by virus isolation.

Early diagnosis of cytomegalovirus infection in renal transplant and dialysis patients by DNA-DNA hybridisation assay

One hundred forty-eight urine specimens were collected from 47 renal transplant and dialysis patients and screened for the detection of cytomegalovirus (CMV). Diagnosis of CMV infection was suggested in 17 out of 47 patients (36.2%) by more than one of the five methods used. DNA hybridisation assay (DNA HA) using 32P-labelled probe detected CMV DNA in 15 (31.9%) of 47 patients, whereas virus isolation on conventional tube cell cultures (CTC), immunofluorescence incorporating monoclonal antibodies on centrifugation vial cultures (IF), complement fixation test (CFT), and electron microscopy (EM) yielded positive results in only nine (19.2%), 12 (25.2%), 11 (23.4%), and one (2.1%) of 47 patients, respectively. The significance of these results obtained by DNA HA lies not only in the apparent increase in number of patients diagnosed, but also in both early and rapid detection of CMV DNA. More importantly, the DNA HA is highly specific in that it correlates accurately with clinical and laboratory data characteristic of CMV disease. In respect of clinically manifest CMV disease, the specificity of DNA HA, CTC, IF, CFT, and EM was 87.5, 43.7, 56.3, 43.7, and 6.3%, respectively. These advantages of DNA HA make it the test of choice for early diagnosis of CMV infections in immunosuppressed patients.

New methodologies. Their role in pediatric pathology

Recombinant DNA technology is providing the means for early and specific etiologic diagnoses of infectious and immunologic diseases, replacing or complementing older methodologies. The new tools that have been so useful in detecting gene rearrangements in leukemias and lymphomas are being applied to the unresolved questions of embryogenesis and disorderly cell differentiation and are being used to completely re-map the nervous system. Flow cytometry and cell sorting are becoming standard features of clinical laboratories and are instrumental not only in defining alterations in lymphoid cell populations but in examining cellular functions as well as surface markers. Bone marrow and organ transplantation for genetic, metabolic, and neoplastic diseases will be performed much more effectively as these newer technologies are applied to the selection of compatible donors and to the follow-up of rejection and infectious complications.

Detection of human cytomegalovirus by slot-blot hybridisation assay employing oligo-primed 32P-labelled probe

A 32P-labelled Hind III-0 DNA fragment (nine Kilobases; Kb) from human cytomegalovirus AD-169 (HCMV) was used in slot-blot hybridisation assay for the detection of HCMV in clinical samples. The results obtained with DNA hybridisation assay (DNA HA) were compared with virus isolation using conventional tube cell culture (CTC) and centrifugation vial culture (CVC), immunofluorescence (IF), and complement fixation test (CFT). Of 15 CTC-positive samples, 13 were positive with DNA HA (sensitivity 86.7%). Also, 14 additional samples were DNA HA-positive but CTC-negative. CVC and/or IF confirmed the diagnosis in nine of 14; the remaining five samples were from three patients who showed fourfold rising antibody titre by CFT. Although DNA HA using 32P-labelled probes is relatively cumbersome and expensive, it is a valuable test for quantitation of viral shedding in patients with HCMV infections who may benefit from antiviral therapy.

Combined use of sonication and monoclonal antibodies for the detection of early and late cytomegalovirus antigens in centrifugation cultures

A total of 157 clinical specimens was inoculated into shell vials and conventional tube cell cultures containing confluent monolayers of human embryonic lung fibroblasts (HELF). Of 31 clinical cytomegalovirus (CMV) isolates, 30 specimens (96.8%) were positive by the immunofluorescence method on centrifugation vial cultures (CVC-IF), whereas the cytopathic effects (CPE) of CMV were detected in only 14 specimens (45.2%) in conventional tube cell cultures (CCC), P less than 0.001 and in 22 specimens (70.9%) in centrifugation vial cultures (CVC-P), P less than 0.1. Significantly more fluorescent foci were detected in centrifugation cultures inoculated with sonicated urine samples (P less than 0.001). CVC-P is more sensitive than CCC for the diagnosis of CMV (P less than 0.05), and a highly significant difference was observed when we compared the mean day to initial detection of CPE (P less than 0.001). For optimal detection of CMV, both CVC-IF and CVC-P should be used for the laboratory diagnosis of this virus infection.

New and sensitive standard cell culture technique for the detection of cytomegalovirus in clinical specimens

Conventional tube cell culture has been recognised as the most sensitive technique available for human cytomegalovirus (HCMV) detection. Low-speed centrifugation of specimen inocula onto cell culture monolayers has been shown to increase the efficiency of infection with the AD 169 strain of HCMV. Therefore a centrifugal force of 900g for 1 hour at 37 degrees C was used to enhance the detection of HCMV cytopathic effect (CPE) in shell vials that contained circular coverslips with a monolayer of human embryonic lung (HEL) fibroblasts. Of 195 specimens, HCMV CPE was detected in 18 specimens (9.02%) on shell vial culture assay, whereas conventional tube cell culture was positive in only 13 specimens (6.6%). The shell vial culture assay was significantly more sensitive (P less than 0.05). Furthermore the development of the cytopathic effect on shell vial culture assay was significantly earlier (P less than 0.01) and more extensive. Urine samples were sonicated and the results obtained with immunofluorescence using human immune serum demonstrated that sonication increased both the intensity of fluorescence and number of fluorescent foci of HCMV-infected cells and also decreased the non-specific fluorescence of the background.

Detection of cytomegalovirus in shell vial cultures by using a DNA probe and early nuclear antigen monoclonal antibody

An in situ biotinylated DNA probe assay was evaluated as an adjunct to anti-cytomegalovirus early nuclear antigen indirect immunofluorescence and cytopathic effect on cytomegalovirus-infected monolayers in shell vial cultures. Viral infection was detected by early nuclear antigen indirect immunofluorescence at 24 h and by DNA probe assay and shell vial cytopathic effect at 5 days.

Clinical laboratory applications of monoclonal antibodies

Monoclonal antibody (MAb) technology is well recognized as a significant development for producing specific serologic reagents to a wide variety of antigens in unlimited amounts. These reagents have provided the means for developing a number of highly specific and reproducible immunological assays for rapid and accurate diagnosis of an extensive list of diseases, including infectious diseases. The impact that MAbs have had in characterizing infectious disease pathogens, as well as their current and future applications for use in clinical microbiology laboratories, is reviewed. In addition, the advantages (and disadvantages) of the use of MAbs in a number of immunoassays, such as particle agglutination, radioimmunoassays, enzyme-linked immunosorbent assays, immunofluorescent-antibody assays, and immunohistology, are explored, including the use of these reagents in novel test system assays. Also, nucleic acid probe technology is compared with the use of MAbs from the perspective of their respective applications in the diagnosis of infectious disease agents. There is no question that hybridoma technology has the potential to alter significantly the methods currently used in most clinical microbiology laboratories.

Rapid detection of cytomegalovirus by fluorescent monoclonal antibody staining and in situ DNA hybridization in a dram vial cell culture system

By using dram vial cell culture methods, three commercially available tests for cytomegalovirus (CMV) detection were compared: direct fluorescent monoclonal antibody staining for CMV-specific early and late antigens (direct FA), indirect fluorescent monoclonal antibody staining for a CMV-specific early antigen (indirect FA), and in situ DNA hybridization with a biotinylated CMV-specific DNA probe kit (DNA probe). Of those tests, only the indirect FA provided consistent, reliable virus detection within the initial 24 h postinfection for serial 10-fold dilutions of CMV AD169 (laboratory strain) and for three selected urine samples. However, when used prospectively, the indirect FA failed to detect virus within the initial 10 days postinfection in 15 of 78 consecutive specimens that were eventually positive by cell culture. Although the indirect FA was more sensitive than the direct FA or DNA probe, its utility appeared limited to specimens with high CMV concentrations. On the basis of these data, we recommend that indirect FA be reserved as an adjunct to standard cell culture for selected samples in diagnostic hospital laboratories.

Correlation of cytomegalovirus (CMV) detection in urine by tissue culture virus isolation, early antigen immunofluorescence test and nucleic acid hybridization

The sensitivity and specificity of the early antigen immunofluorescence test and of the hybridization assay were compared with those of the development of a cytopathic effect on HF MA 23 cell monolayers in tissue culture. Of 818 clinical specimens tested, 125 specimens produced CMV cytopathic effect in tissue culture within four weeks after inoculation. Of the 125 specimens, 71 were positive for CMV after 36 h by early antigen immunofluorescence test (sensitivity 56.8%). Of the remaining 693 culture-negative specimens, seven were positive by early antigen immunofluorescence test (specificity, 99%). A hybridization assay using a commercial kit with the biotinylated Bam H I AB DNA fragment of HCMV Towne strain and horseradish peroxidase streptavidin conjugate, detected 60 pg of HCMV DNA. In this assay 104 urine specimens were tested. Compared with tissue culture, this hybridization assay had a sensitivity of 69.5%, a specificity of 60.3% and a correlation of 63.4%, at which 25 of 33 tissue culture positive samples had positive hybridization results, and 27 of 68 tissue culture negative samples also gave positive hybridization results. An additional hybridization assay, using the biotinylated Hind III L fragment of HCMV AD 169 and 125J streptavidin conjugate, detected 30 pg HCMV DNA. In 179 urine specimens simultaneously tested by tissue culture, 28 of 33 positive tissue culture specimens were positive in the hybridization assay. 37 of 146 negative tissue culture specimens gave positive hybridization signals (sensitivity 84.8%, specificity 74.7%, correlation 76.5%).

The use of ELISA and nonradioactive DNA hybridization assays for the detection of human cytomegalovirus

A hybridization assay using a biotinylated DNA probe was compared to both ELISA and direct isolation methods for detecting human cytomegalovirus (HCMV). The biotin labeled HCMV AD 169 HindIII-O-DNA fragment was used in a dot-blot assay to screen for the presence of HCMV in 186 urine specimens obtained from kidney transplant patients. The biotinylated HCMV HindIII-O probe could detect 3 log10 TCID50 units of HCMV. Urine specimens were also examined for the presence of HCMV by either ELISA or direct isolation of virus in tissue culture. The HindIII-O fragment detected 12 of 20 culture positive samples (sensitivity, 60%). There were 5 samples which were probe positive and cell culture negative (specificity, 97%). The ELISA assay also detected 12 of 20 culture positive samples (sensitivity, 60%). Eight samples were ELISA positive, cell culture negative (specificity, 95%). Seven specimens were positive by all three criteria. Five specimens which were both ELISA positive and probe positive were cell culture negative. The ELISA positive, probe positive, culture negative specimens originated from patients who gave a culture positive specimen within 10 days of the original sample. The combination of probe and ELISA assays detected 16 of the 20 culture positive specimens (sensitivity, 80%). The combined use of biotinylated DNA probes and ELISA allows the detection of HCMV in urine specimens with good sensitivity and specificity.

Detection of herpes simplex virus in conventional tube cell cultures and in shell vials with a DNA probe kit and monoclonal antibodies

Specimens submitted for diagnosis of herpes simplex virus (HSV) infection were inoculated into shell vials and reacted with a commercial DNA probe kit (Pathogene; Enzo Biochem, Inc., New York, N.Y.) and an immunofluorescence assay at 16 h postinoculation. The results were compared with isolation of the virus in conventional tube cell cultures. Of 504 specimens, 105 (20.8%) were positive for HSV. Of the 105, 93 HSV-positive specimens (89%) were detected by all three assay systems. Maximum detection of HSV (100 of 105 [95%]) was obtained by probe or monoclonal antibody assay in shell vials, which had sensitivities of 98 and 97%, respectively, compared with viral recovery in conventional tube cell cultures (mean time for recognition of cytopathic effects, 2 days). Both shell vial assays were 99% specific. The DNA probe kit may be used as an alternative to a monoclonal antibody and fluorescence assay in shell vials as a diagnostic method for rapid laboratory detection of HSV infection.

Diagnostic deoxyribonucleic acid probes for infectious diseases

Virtually all microorganisms contain some unique nucleotide sequences which can be the target of deoxyribonucleic acid probes. Probes have been used successfully to identify a wide variety of pathogens from the simple ribonucleic acid-containing polioviruses to the complex filarial worms Brugia malayi. Probe technology offers the clinical laboratory the potential both to extend the types of pathogens that can be readily identified and to reduce significantly the time associated with the identification of fastidious microorganisms. Over a dozen commercially prepared deoxyribonucleic acid probe tests are now available. This article explores the development of deoxyribonucleic acid probe tests and reviews the sensitivity, specificity, and predictive values of many of the diagnostic probes developed during the last several years. Prospects for newer, more sensitive detection systems for the products of hybridization reactions are also reviewed.

Detection of cytomegalovirus by 24-well plate centrifugation assay using a monoclonal antibody to an early nuclear antigen and by conventional cell culture

During a 12-month period, two methods for detection of cytomegalovirus (CMV) in 1624 clinical specimens were compared: (1) centrifugal inoculation of MRC-5 cells on coverslips in 24-well plates and staining with a monoclonal antibody to CMV early nuclear antigen after incubation for 40 h (EA assay), and (2) conventional tube cell culture. CMV was identified in 183 (11.3%) specimens from 113 different patients. The EA assay was positive for CMV in 144/183 specimens (79%), and CMV was detected by recognition of specific cytopathic effect (CPE) in conventional cell culture in 143/183 (78%). Both methods yielded CMV in 56% of the specimens (104/183). CMV was detected by EA assay alone in 22% (40/183) and only by CPE in 21% (39/183) of the positive specimens. When all specimen types were considered, there was no significant difference in the detection of CMV between the two methods. However, bronchoalveolar lavage (BAL) fluids yielded CMV more frequently by EA assay than by CPE (58 compared to 48 of 574, p = 0.0178), and CMV was detected in blood specimens more often by CPE than by EA assay (20 compared to one of 149, p less than 0.0001). In addition to CMV, other viruses were recovered by conventional tube cell culture, including herpes simplex virus (HSV) type 1 from 17 BAL fluids (two of which were positive for CMV by EA assay) and one liver biopsy and adenovirus serotype 4 from four separate urine specimens and three gastrointestinal tract biopsies from one patient.(ABSTRACT TRUNCATED AT 250 WORDS)