Rapid detection of cytomegalovirus by tissue culture, centrifugation, and immunofluorescence with a monoclonal antibody to an early nuclear antigen

Maternal and congenital human cytomegalovirus infection: laboratory testing for detection and diagnosis

Human cytomegalovirus (CMV) is the leading cause of congenital infection worldwide and the most common cause of non-genetic sensorineural hearing loss. As there is no vaccine or other specific intervention to prevent congenital CMV infection, there is a need to identify maternal and congenital infections with sensitive and specific testing as early as possible. There is no widely accepted practice for screening during pregnancy or in all newborns for identification of possible cases of congenital CMV. Currently, screening during pregnancy is limited to those identified as at risk followed by fetal and/or neonatal testing when congenital infection is suspected. This review focuses primarily on the current status of laboratory testing for diagnosis of maternal and congenital CMV infections. Primary maternal infection is best diagnosed using serologic testing, including CMV IgM, IgG, and avidity testing, while fetal infection should be assessed by nucleic acid amplification testing (NAAT) of amniotic fluid. Urine and saliva NAATs are the mainstay for diagnosis of congenital CMV in the first 3 weeks of life. Testing of dried blood spots can be useful for diagnosis of congenital CMV outside of the newborn period. The gaps in knowledge such as the prognostic value of viral loads in various sample types are addressed.

Successful Implementation of Single Urine Polymerase Chain Reaction Test for Evaluating Suspected Cytomegalovirus Infection in Neonates

Overuse of laboratory investigations is viewed as medical waste. In the past, to diagnose congenital cytomegalovirus (CMV) infection, consecutive urine culture samples were obtained. With the advent of polymerase chain reaction (PCR) technology, 1 urine specimen should be enough. We conducted this quality improvement study to look at the effect of a practice change from 3 to 1 urine specimen for PCR testing.

Evaluation of serial urine viral cultures for the diagnosis of cytomegalovirus infection in neonates and infants

Cytomegalovirus (CMV) is the most common cause of congenital infection worldwide. Urine viral culture is the standard for CMV diagnosis in neonates and infants. The objectives of this study were to compare the performance of serial paired rapid shell vial cultures (SVC) and routine viral cultures (RVC), and to determine the optimal number of cultures needed to detect positive cases. From 2001 to 2011, all paired CMV SVC and RVC performed on neonates and infants less than 100 days of age were recorded. Testing episodes were defined as sets of cultures performed within 7 days of one another. A total of 1264 neonates and infants underwent 1478 testing episodes; 68 (5.4%) had at least one episode with a positive CMV culture. In episodes where CMV was detected before day 21 of life, the first specimen was positive in 100% (16/16) of cases. When testing occurred after 21 days of life, the first specimen was positive in 82.7% (43/52) of cases, requiring three cultures to reach 100% detection. The SVC was more prone to assay failure than RVC. Overall, when RVC was compared to SVC, there was 86.0% positive agreement and 99.9% negative agreement. In conclusion, three serial urine samples are necessary for detection of CMV in specimens collected between day of life 22 and 99, while one sample may be sufficient on or before day of life 21. Though SVC was more sensitive than RVC, the risk of SVC failure supports the use of multimodality testing to optimize detection.

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.

Dried blood spot real-time polymerase chain reaction assays to screen newborns for congenital cytomegalovirus infection

CONTEXT

Reliable methods to screen newborns for congenital cytomegalovirus (CMV) infection are needed for identification of infants at increased risk of hearing loss. Since dried blood spots (DBS) are routinely collected for metabolic screening from all newborns in the United States, there has been interest in using DBS polymerase chain reaction (PCR)-based methods for newborn CMV screening.

OBJECTIVE

To determine the diagnostic accuracy of DBS real-time PCR assays for newborn CMV screening.

DESIGN, SETTING, AND PARTICIPANTS

Between March 2007 and May 2008, infants born at 7 US medical centers had saliva specimens tested by rapid culture for early antigen fluorescent foci. Results of saliva rapid culture were compared with a single-primer (March 2007-December 2007) and a 2-primer DBS real-time PCR (January 2008-May 2008). Infants whose specimens screened positive on rapid culture or PCR had congenital infection confirmed by the reference standard method with rapid culture testing on saliva or urine.

MAIN OUTCOME MEASURES

Sensitivity, specificity, and positive and negative likelihood ratios (LRs) of single-primer and 2-primer DBS real-time PCR assays for identifying infants with confirmed congenital CMV infection.

RESULTS

Congenital CMV infection was confirmed in 92 of 20,448 (0.45%; 95% confidence interval [CI], 0.36%-0.55%) infants. Ninety-one of 92 infants had positive results on saliva rapid culture. Of the 11,422 infants screened using the single-primer DBS PCR, 17 of 60 (28%) infants had positive results with this assay, whereas, among the 9026 infants screened using the 2-primer DBS PCR, 11 of 32 (34%) screened positive. The single-primer DBS PCR identified congenital CMV infection with a sensitivity of 28.3% (95% CI, 17.4%-41.4%), specificity of 99.9% (95% CI, 99.9%-100%), positive LR of 803.7 (95% CI, 278.7-2317.9), and negative LR of 0.7 (95% CI, 0.6-0.8). The positive and negative predictive values of the single-primer DBS PCR were 80.9% (95% CI, 58.1%-94.5%) and 99.6% (95% CI, 99.5%-99.7%), respectively. The 2-primer DBS PCR assay identified infants with congenital CMV infection with a sensitivity of 34.4% (95% CI, 18.6%-53.2%), specificity of 99.9% (95% CI, 99.9%-100.0%), positive LR of 3088.9 (95% CI, 410.8-23 226.7), and negative LR of 0.7 (95% CI, 0.5-0.8). The positive and negative predictive values of the 2-primer DBS PCR were 91.7% (95% CI, 61.5%-99.8%) and 99.8% (95% CI, 99.6%-99.9%), respectively.

CONCLUSION

Among newborns, CMV testing with DBS real-time PCR compared with saliva rapid culture had low sensitivity, limiting its value as a screening test.

Enhancement of cytomegalovirus detection in mink lung cells using CMV Turbo

BACKGROUND

Detection of HCMV from clinical specimens was a slow process until the development of shell vial method with staining for immediate early antigen (IEA). Culture though still considered insensitive is widely used for other than blood samples. A method to improve culture sensitivity is desirable.

OBJECTIVES

TurboTreat, a CMV pretreatment medium from Diagnostic Hybrids Inc., was evaluated on Mv1Lu, R-Mix and MRC-5 cells for improved sensitivity for HCMV detection.

STUDY DESIGN

Monolayers of Mv1Lu, R-Mix and MRC-5 cells in 48-well plates were treated with TurboTreat for overnight (o/n), 4 h or left untreated and then inoculated with previously positive HCMV specimens. After o/n incubation, cells were fixed, stained and positive cells counted.

RESULTS

CMV TurboTreat enhanced detection 2-3-fold after 4 h treatment and 4-6-fold after o/n treatment in Mv1Lu and R-Mix cells and to a lesser extend in MRC-5 cells with clinical isolates of HCMV. With frozen clinical specimens, Mv1Lu cells treated o/n, 4 h or untreated detected 23, 21 and 15 positive specimens, respectively. R-Mix cells detected 19, 18, and 14 positives, respectively and MRC-5 cells detected 16, 15 and 15 positives, respectively. In no case was a positive detected in another cell line regardless of treatment that was not detected in Mv1Lu treated o/n.

CONCLUSION

The o/n pretreatment with CMV TurboTreat on Mv1Lu cells is the optimum condition of treatment and significantly enhanced the detection of HCMV. Even 4 h pretreatment of Mv1Lu cells showed significant enhancement over untreated Mv1Lu, R-Mix and MRC-5 cells. Pretreatment of Mv1Lu cells with CMV TurboTreat for 4 h or longer increased the sensitivity of rapid HCMV detection.

Deep-etch EM reveals that the early poxvirus envelope is a single membrane bilayer stabilized by a geodetic "honeycomb" surface coat

Three-dimensional "deep-etch" electron microscopy (DEEM) resolves a longstanding controversy concerning poxvirus morphogenesis. By avoiding fixative-induced membrane distortions that confounded earlier studies, DEEM shows that the primary poxvirus envelope is a single membrane bilayer coated on its external surface by a continuous honeycomb lattice. Freeze fracture of quick-frozen poxvirus-infected cells further shows that there is only one fracture plane through this primary envelope, confirming that it consists of a single lipid bilayer. DEEM also illustrates that the honeycomb coating on this envelope is completely replaced by a different paracrystalline coat as the poxvirus matures. Correlative thin section images of infected cells freeze substituted after quick-freezing, plus DEEM imaging of Tokuyasu-type cryo-thin sections of infected cells (a new application introduced here) all indicate that the honeycomb network on immature poxvirus virions is sufficiently continuous and organized, and tightly associated with the envelope throughout development, to explain how its single lipid bilayer could remain stable in the cytoplasm even before it closes into a complete sphere.

Comparison of monoclonal antibodies for immunostaining in the cytomegalovirus shell vial assay on 4,388 specimens

The shell vial assay is a sensitive, rapid test for the detection of cytomegalovirus (CMV) in a variety of specimens. The sensitivity of this assay is dependent on a number of factors including the antibodies used for immunostaining. Monoclonal antibodies to the CMV major immediate-early antigen (p72) from Chemicon (MAB810) and Dupont (NEA-9221) were assessed side by side in duplicate vials on 4,388 specimens from a patient population consisting of > 90% organ transplant recipients. A total of 240 specimens (5.5%) were CMV positive in either one or both vials. Positivity rates were variable across different specimen types but highest (12.9%) in urine specimens. Of the positive specimens, 175 (72.9%) tested positive in both vials, 43 (17.9%) tested positive in the Chemicon-stained vial only, and 22 (9.2%) tested positive in the Dupont-stained vial only (P < 0.01, McNemar's chi-square test). This gave an overall positivity rate of 5.0% for Chemicon antibodies and 4.5% for Dupont. There was no difference in the fluorescent focus counts produced by the two antibody sets. It is concluded that use of the Chemicon antibodies provides increased sensitivity of detection of CMV in the shell vial assay above that afforded by the Dupont antibody.

Effects of enhancing agents on detection of cytomegalovirus in clinical specimens

Dimethyl sulfoxide, dexamethasone, and calcium were tested in combination for their enhancing effects on cytomegalovirus detection in shell vial cultures on 1,579 clinical specimens obtained primarily from adult solid-organ transplant recipients. Fluorescent-focus counts were elevated for the cytomegalovirus-positive urine specimens (P < 0.01) and throat washings (P < 0.05) but not for the tissue biopsy or blood samples. Epidermal growth factor also increased focus counts but provided no additional benefit when used in combination with the other agents. The triple-combination treatment did not increase the number of positive specimens identified.

Rapid detection of active cytomegalovirus infection by in situ polymerase chain reaction on MRC5 cells inoculated with blood specimens

An in situ polymerase chain reaction was developed to amplify immediate early genes of human cytomegalovirus in cells cultured in a 96 well plate and infected with leukocytes. The technical parameters enabling optimal detection of the DNA sequences were defined. The key to this method is the fixation of cells, which facilitates the access of the PCR mixture into the cell nuclei and preserves cell morphology. Such a technique could have wide application for the detection and identification of other infectious viruses in cultured cells very early after inoculation of clinical samples.

Physical and chemical methods for enhancing rapid detection of viruses and other agents

Viral replication events can be enhanced by physical, chemical, or heat treatment of cells. The centrifugation of cells can stimulate them to proliferate, reduce their generation times, and activate gene expression. Human endothelial cells can be activated to release cyclo-oxygenase metabolites after rocking for 5 min, and mechanical stress can stimulate endothelial cells to proliferate. Centrifugation of virus-infected cultures can increase cytopathic effects (CPE), enhance the number of infected cells, increase viral yields, and reduce viral detection times and may increase viral isolation rates. The rolling of virus-infected cells also has an effect similar to that of centrifugation. The continuous rolling of virus-infected cultures at < or = 2.0 rpm can enhance enterovirus, rhinovirus, reovirus, rotavirus, paramyxovirus, herpesvirus, and vaccinia virus CPE or yields or both. For some viruses, the continuous rolling of infected cell cultures at 96 rpm (1.9 x g) is superior to rolling at 2.0 rpm for viral replication or CPE production. In addition to centrifugation and rolling, the treatment of cells with chemicals or heat can also enhance viral yields or CPE. For example, the treatment of virus-infected cells with dimethyl sulfoxide can enhance viral transformation, increase plaque numbers and plaque size, increase the number of cells producing antigens, and increase viral yields. The infectivity of fowl plague virus is increased by 80-fold when 4% dimethyl sulfoxide is added to culture medium immediately after infection. The heat shocking of virus-infected cells also has been shown to have a stimulatory effect on the replication events of cytomegalovirus, Epstein-Barr virus, and human immunodeficiency virus. The effects of motion, chemicals, or heat treatments on viral replication are not well understood. These treatments apparently activate cells to make them more permissive to viral infection and viral replication. Perhaps heat shock proteins or stress proteins are a common factor for this enhancement phenomenon. The utility of these treatments alone or in combination with other methods for enhancing viral isolation and replication in a diagnostic setting needs further investigation.

A microneutralization enzyme immunoassay for antibody to human cytomegalovirus

We have developed a relatively rapid, sensitive and quantitative microneutralization assay for antibody to human cytomegalovirus (HCMV). Cell monolayers in 96-well microtiter plates inoculated with pre-incubated virus-antibody mixtures were fixed after 3 days. Infectious foci were stained with peroxidase-labeled human monoclonal antibody to a 64 kDa immediate early antigen of HCMV, and the plates were read at OD450. The 50% neutralization titer of the antibody was calculated. A study with 20 human sera and a human monoclonal antibody which neutralizes virus showed that this microneutralization enzyme immunoassay is more sensitive than, and as quantitative as, the conventional plaque reduction assay for antibody to HCMV. The neutralizing antibody titers of each sample measured by these two methods showed good correlation (n = 19, r = 0.884). Thus, this new assay is a useful and valid alternative to the conventional method for mass screening of sera and hybridoma fluids, and considerably more rapid.

Monitoring of patients for cytomegalovirus after organ transplantation by centrifugation culture and PCR

A modified centrifugation culture technique and a polymerase chain reaction (PCR) is described for detection of early antigen and IE antigen DNA, respectively, for rapid and sensitive monitoring of active cytomegalovirus (HCMV) infection after organ transplantation. In a preliminary study, 541 clinical specimens (blood, urine, bronchoalveolar lavage, pharyngeal wash, sputum) from 59 organ recipients were assayed for HCMV antigen by centrifugation culture; 144 samples were tested by PCR simultaneously. Antigenemia detected by centrifugation culture correlated strongly with active HCMV infection and clinical symptoms and proved useful for monitoring the efficacy of antiviral therapy. PCR was more sensitive in an earlier phase of infection when centrifugation culture was still negative. The clinical usefulness of both methods is discussed.

Diagnosis of cytomegalovirus infection: a review

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Cytomegalovirus infection and disease after liver transplantation. An overview

Cytomegalovirus is the single most important pathogen in clinical transplantation. Although much progress has been made in our understanding of the molecular biology and epidemiology of CMV infection and in our ability to diagnosis and treat CMV disease, it remains a major cause of morbidity but is no longer a major cause of mortality after liver transplantation. Risk factors for CMV disease after liver transplantation include donor and recipient serologic status, the use of antilymphocyte therapy, and retransplantation. CMV disease occurs early after transplantation, and the most frequent site of disease is the hepatic allograft. We have treated 79 patients with intravenous ganciclovir, with ultimate control of disease achieved in 69 patients (87.3%). Preliminary results using intravenous immunoglobulin and oral acyclovir for CMV prophylaxis in high-risk patients have been encouraging. In addition to producing clinical syndromes. CMV may have direct immunologic effects and is a marker of the net state of immunosuppression.

Detection of human cytomegalovirus in clinical specimens by centrifugation culture with a nonhuman cell line

The sensitivities of MRC-5 and mink lung (ML) cells in centrifugation culture were compared simultaneously for the detection of cytomegalovirus (CMV) IE antigen (immediate-early antigen) from clinical specimens. Of 413 samples assayed, 51 (12%) were positive for CMV by both centrifugation and standard cell culture. At 20 h postinoculation (p.i.), 46 of 51 (90.2%) CMV-positive specimens were detected in ML cells. At 40 h p.i., 50 of 51 (98.0%) CMV-positive specimens were detected in ML cells, compared with 48 of 51 (94.0%) in MRC-5 cells. There was no significant difference in the detection of CMV in either cell line by centrifugation culture. However, in 19 of 23 positive samples that had countable foci at 20 h p.i., there was a 25% increase in the number of positive foci observed for ML cells compared with MRC-5 cells. Less toxicity was also noted for ML cells than for MRC cells, particularly in viral blood specimens. These data suggest that ML cells are comparable to MRC-5 cells for the rapid detection of CMV by centrifugation culture.

Evaluation of a microtiter plate fluorescent-antibody assay for rapid detection of human cytomegalovirus infection

The use of monoclonal antibody (MAb) p63-27, which is reactive with the major immediate-early human cytomegalovirus (HCMV) protein pp72, was explored for the rapid diagnosis of HCMV viruria. The rapid assay detected all but 1 of 19 specimens identified by standard virus isolation methods from 1,676 newborn urine specimens, achieving a sensitivity of 94.5% and a specificity of 100%. The monoclonal antibody recognized 260 randomly obtained clinical isolates of HCMV, indicating the suitability of this reagent for use in screening assays. The sensitivity of the microtiter plate method declined rapidly for specimen from older infants and children with congenital CMV infection and virus-infected children attending a day-care center and was judged to be unacceptable for screening populations in this age group.

Temporal patterns of immunoblot-reactive antibodies to cytomegalovirus in transplant recipients

A total of 234 sera from 44 allograft recipients were compared with 12 sera from 9 immunocompetent patients with symptomatic cytomegalovirus (CMV) infection and with 20 sera of 20 healthy individuals with latent CMV infection. The presence of immunoreactive proteins was not associated with a specific transplant group or with different immunosuppressive regimens but rather with the kinetics of the immune response. Acute phase sera demonstrated early antibodies to proteins p38 and p48, followed by high or still rising antibodies to high molecular weight proteins, particularly p150, and their later decline to persistent lower levels. Convalescent phase sera were identified serologically by the transient appearance of IgG antibodies directed to 22-26 kDa polypeptides. Immunoreactive p44 was present in 85% of all patients with mild disease and in 40% of all patients with severe CMV disease. When tested in parallel, the immunoblot analysis was shown to be a more sensitive indicator of early CMV antibodies in allograft recipients than the ELISA technique.

New monoclonal antibodies for the detection of immediate early antigens of cytomegalovirus

Two new monoclonal antibodies, CIE-1 and CIE-2, were developed for the rapid detection of human cytomegalovirus (HCMV) infection. They were found to be reactive with immediate early protein of HCMV in the nuclei of infected fibroblasts, as early as 3 hours post-infection. By radioimmunoprecipitation, CIE-1 was found to react with a protein with an apparent molecular weight of 70,000, whereas CIE-2 precipitated 2 proteins of 70,000 and 72,000 daltons, respectively. Both monoclonal antibodies recognized three prototype strains of HCMV: AD-169, Towne, and Davis, and did not cross-react with other human herpesviruses. CIE-1 and CIE-2 were compared with four commercial anti-HCMV monoclonal antibodies (Clonab, Dupont, Sera-Lab and Syva) by testing 88 clinical isolates. Culture confirmation tests and shell vial assays showed that CIE-1 and CIE-2 were more sensitive than several of these reagents and equally sensitive to the Dupont reagent. Moreover, CIE-1 and CIE-2 produced a bright, sharp staining of the nuclei of infected cells. These monoclonal antibodies should thus be valuable in rapid diagnosis of HCMV.

Comparison of two methods for rapid detection of cytomegalovirus viraemia in cell culture

Two methods for rapid CMV viraemia detection in cell culture with immunoperoxidase staining performed 40 h post-inoculation were compared, on 230 blood samples: (1) a 24-well plate centrifugation assay and (2) a 25-cm2-culture flask technique, without centrifugation. The flask technique was significantly more sensitive than the 24-well plate technique. Moreover, the flask assay was more cost-effective and offered other advantages such as easier sterile handling and less damage of the cell monolayer.

Rapid diagnosis of cytomegalovirus infections by direct immunoperoxidase staining with human monoclonal antibody against an immediate-early antigen

Direct immunoperoxidase technique using a horseradish peroxidase (HRP)-conjugated Fab' fragment of human monoclonal antibody (humab C7), designated HRP-C7, was evaluated as a rapid diagnosis of cytomegalovirus (CMV) infection. A total of 138 clinical specimens consisting of 124 urine samples and 14 oral swabs were examined for CMV by the direct HRP-C7 staining in comparison with conventional virus isolation. The number of CMV-positive samples by each method was 40 (29.0%) for the former and 37 (26.8%) for the latter, respectively. By HRP-C7 staining, CMV was identifiable within 24 hr after inoculation. By conventional isolation method, an average of 10.3 days had passed before cytopathic effect characteristic of CMV appeared in the cell culture. Some false-positive and false-negative cases were discussed in relation to toxicity of urine samples, storage of the samples, and amount of CMV in the sample. The sensitivity and specificity of HRP-C7 method against conventional isolation method were 89.2% and 93.1%, respectively. Thus, HRP-C7 staining is useful for a rapid diagnosis of CMV infections.

Comparison between three rapid methods for direct diagnosis of influenza and the conventional isolation procedure

Besides the rapid diagnostic tests based on influenza A and B antigens nucleoproteins detection, which are routinely used, the isolation of influenza strains is still required to obtain recent variant isolates for full antigenic characterization, in order to up-date the influenza vaccine composition. To increase the rapidity and the efficacy of the virus growth, we implemented a culture test in 24-well plates by centrifugation of samples on to LLCMK2 cells in the presence of trypsin. This test was routinely applied to 331 nasopharyngeal swabs collected during the influenza A outbreak in the winters 1988-1989 and to 962 in 1989-1990. The centrifugation culture assay has been compared with the direct detection of NP antigens in the clinical samples by immunofluorescence and capture ELISA tests and with the conventional virus isolation by inoculation of the samples to embryonated eggs and to LLCMK2 cell cultures. Compared with the NP antigen detection tests, the centrifugation culture assay closely correlated (r = 0.95) and the sensitivity and specificity were also excellent, 93.4% and 99.6%, respectively. Compared with the conventional culture assays, the centrifugation culture markedly increased the performance (five times) and rapidity (2 days) of influenza virus isolation and identification.

Optimization of in situ hybridization for detection of viral genomes in cultured cells on 96-microwell plates: a cytomegalovirus model

In situ hybridization (ISH) for identification of infectious replicative cytomegalovirus (CMV) in cell culture microplates (96 microwells) infected by clinical specimens was tested by using a biotin-labeled DNA probe and an avidin-alkaline phosphatase conjugate. A total of 395 specimens were examined by using ISH and a monoclonal antibody (MAb) specific for an early antigen of CMV. Of 47 specimens that gave a positive signal for CMV by ISH, 33 were confirmed virus positive by MAb staining. Of 141 blood samples tested, 4.96% were positive by ISH, and 0.7% were positive by the MAb technique. ISH shows 40% more sensitivity than MAb staining. This technique should be widely applicable for the specific identification of viral isolates (e.g., herpesvirus, myxovirus, paramyxovirus, and enterovirus) in cell culture 96-microwell microplates, thereby making it feasible to screen a larger number of samples than is possible with classical methods using conventional culture tubes, shell vials, or 24-well plates.

Comparison of MRC-5 and U-373MG astrocytoma cells for detection of cytomegalovirus in shell vial centrifugation cultures

U-373MG astrocytoma cells are susceptible to human cytomegalovirus (CMV) infection and offer the advantage of a continuous cell line for clinical laboratory use. U-373MG to MRC-5 cells for detection of CMV by centrifugation culture were therefore compared. At 20 h, 10 (6.1%) versus 12 (7.4%) of 163 clinical specimens were positive for CMV, and at 40 h, 12 (7.4%) versus 17 (10.4%) were positive in U-373MG and MRC-5 cells, respectively. Substantial toxicity was found in U-373MG cells (84%) when inoculated with blood specimens. For detection of CMV in centrifugation culture, MRC-5 cells are superior due both to higher sensitivity and lesser toxicity.

Optimizing recovery of cytomegalovirus in the shell vial culture procedure

We have investigated three factors that may be related to the recovery of cytomegalovirus (CMV) using the shell vial culture procedure. First, we compared fluorescent-antibody staining of shell vial cultures using a monoclonal antibody to a CMV immediate early antigen at 16 vs 40 hr after inoculation. Of 332 routinely submitted specimens cultured in duplicate and stained at the different times, 25 (7.5%) were positive at 16 hr and 32 (9.6%) were positive at 40 hr. The increased yield was 28%. Second, we analyzed the effect of using duplicate shell vials (both stained at 40 hr) for all routinely submitted CMV cultures. During a 6-month period, 272 (12.5%) of the 2157 cultures processed with duplicate shell vials were positive, including 222 positive in both vials and 50 positive in only one. Assuming that a single-vial setup would have detected 50% of those positive in only one of the two vials, the increased yield attributable to the duplicate vial was estimated at 10% (25/(222 + 25)). Third, we investigated the effects of seeding density and culture age on the shell vial assay. Cell age of greater than 1 day was associated with a decrease in sensitivity both in cultures that were confluent and in those that were subconfluent at the time of inoculation. Incorporating these findings in the routine shell vial culture procedure used in our Clinical Virology Laboratory has resulted in a greater overall detection of CMV in shell vial cultures than in conventional 6-week tube cultures.

Diagnosis of cytomegalovirus infection in cyclosporin-treated renal allograft recipients

The relative merits of antibody response and virus shedding as markers of cytomegalovirus (CMV) infection among cyclosporin-treated renal allograft recipients were analysed. CMV-specific antibody was assayed by IgG-specific radioimmunosorbent test (RIST) and by complement fixation test (CFT). CMV shedding was assayed by virus isolation and by the rapid test immediate early nuclear antigen detection (IENAD). RIST and CFT detected seroconversion in similar numbers of patients, but the former test was the more sensitive when CMV antibody was sought in pretransplant sera to differentiate primary from recurrent infection. IENAD detected or excluded CMV shedding for more urine specimens than virus isolation (462/515 [90%] vs. 366/515 [71%]), but the reverse applied to saliva specimens (33/57 [58%] vs. 54/57 [95%]). The high specificity of IENAD allowed positive results by IENAD to be accepted when virus isolation failed to provide a result. IENAD was, however, less sensitive than virus isolation even when specimens yielding CMV by IENAD, but no result by virus isolation, were included in the analysis (27/44 [61%] vs. 38/44 [86%]). Assays of both antibody response and virus shedding were required to maximise the diagnosis of recurrent CMV infections, but the former assay detected all primary CMV infections. The diagnostic implications of these results are discussed.

Early detection of active cytomegalovirus (CMV) infection after heart and kidney transplantation by testing for immediate early antigenemia and influence of cellular immunity on the occurrence of CMV infection

To determine the incidence of active cytomegalovirus (CMV) infection after organ transplantation and its relationship with the immune system, 55 renal and 14 cardiac transplant recipients were closely monitored for active CMV infection (expression of CMV immediate early antigen in granulocytes--antigenemia--and positive cultures) and immune parameters. All 19 CMV-seronegative recipients with seronegative donors remained seronegative, showing that no CMV transmission occurred by leukocyte-depleted blood products. Primary CMV infection occurred in 4 of 11 (36%) patients with positive donors and was symptomatic in 1 (9%) patient. Active CMV infection was found in 29 of 39 (74%) seropositive patients and was symptomatic in 3 (8%) patients. CMV antigenemia was always the first indication of active CMV infection (antigenemia, on average, at day 45 +/- 15; immunoglobulin G rise at day 71 +/- 36; and positive cultures at day 70 +/- 17). Cellular immunity, as measured by lymphocyte proliferation (LPT), proved to be of importance in the prevention of active CMV infection, as 14 of 15 patients with negative LPT obtained active CMV infections with antigenemia and positive cultures, whereas 1 of 10 patients with positive LPT did so (P less than 0.0001).

Laboratory and clinical diagnosis of human cytomegalovirus infection after transplantation

Urine and blood specimens from 32 recipients of allograft organ transplant were investigated for human cytomegalovirus (HCMV) by conventional cell culture, indirect immunofluorescent assay subsequent to the rapid cell culture and DNA-DNA hybridization. The results showed that the rapid cell culture technique might be the best method for rapid detection of active HCMV infection after transplantation because it possesses the advantages of simplicity, speediness, sensitiveness, and high reliability of detecting productive HCMV infection. The major symptoms were prolonged or intermittent fever unresponsive to antibiotics, dysfunction or loss of function of the transplanted organ, pulmonary infiltrates and leukopenia. As our results suggested, reactivation of a latent infection appears to be the most probable etiologic factor contributing to HCMV infection after transplantation.

Early detection of cytomegalovirus in cell culture by a new monoclonal antibody, CCH2

A CMV monoclonal antibody, CCH2, produced in this laboratory was evaluated for rapid detection of CMV. Two staining procedures, immunofluorescence and an immunoenzymatic technique using biotin-streptavidin peroxidase, were compared. The CCH2 monoclonal antibody was used to demonstrate early CMV antigen in cell culture 24 h after inoculation of 598 urine samples from kidney transplanted patients by indirect immunofluorescence in comparison with virus isolation. One hundred and sixty of the specimens were stained additionally by an immunoenzymatic technique and the results were compared. CMV was isolated from 170 out of 598 specimens within 6 weeks. Early CMV antigen was demonstrated in 114 of these specimens by immunofluorescence giving a sensitivity of 67% and a specificity of 95%. In the comparison with the immunoenzymatic staining procedure the results for all three tests agreed for 81% (130/160) of the specimens. After resolving discordant results into true positives and true negatives, the sensitivity was 87, 85 and 70%, respectively for virus isolation, immunoenzymatic staining and immunofluorescence and the specificity 100, 96 and 99%. The CCH2 monoclonal antibody proved to be useful for rapid detection of CMV in urine specimens and using immunoenzymatic staining with biotin-streptavidin a sensitivity comparable to that of virus isolation was found.

Effect of treatment of shell vial cell cultures with dimethyl sulfoxide and dexamethasone and age of MRC-5 monolayers for detection of cytomegalovirus

Pretreatment of MRC-5 cell monolayers in commercially prepared shell vials with 1% dimethyl sulfoxide (DMSO) and 10(-5) mol/L dexamethasone (DEX) was evaluated. Preliminary experiments indicated enhanced infectivity of AD-169 for pretreated MRC-5 cells in shell vials of ages 9 and 16 days. Compared with untreated shell vials, DMSO-DEX increased positivity (day 9, 19 vs. 26 shell vials, p less than 0.03; day 16, 13 vs. 29 shell vials, p less than 0.001) and increased the mean number of fluorescent foci (days 9 and 16, p less than 0.001). Pretreatment of 8-15-day-old monolayers was evaluated clinically using 146 urine specimens. Fifty specimens were positive for cytomegalovirus (CMV) in both treated and untreated shell vials with ten positive in untreated only and three positive in treated only (p = NS). The median number of fluorescent foci was not significantly higher in treated shell vials. Increased toxicity of MRC-5 cells was observed in treated monolayers (p less than 0.0001). Pretreatment with DMSO-DEX did not enhance CMV isolation from clinical specimens and can be toxic to MRC-5 monolayers.

Continuous high-speed rolling versus centrifugation for detection of herpes simplex virus

Specimens submitted for diagnosis of herpes simplex virus infections were inoculated into shell vials and conventional culture tubes. Inoculated culture tubes were incubated with rolling at 96 rpm. Immunoperoxidase (IP) staining and cytopathic effects (CPE) were used to detect positive cultures. At 24 h, 42 (53%) of the rolled cultures were positive for CPE, while only 16 (21%) of the shell vials were CPE positive (P less than 0.01). No difference in sensitivity was seen between rolled and shell vial cultures that were inoculated with high-titered viral preparations and IP stained at 16 h. However, when low-titered preparations were used, 39 of 41 (95%) were IP positive by the high-speed roller method at 64 h postinoculation, while only 24 of 41 (58%) were IP positive with shell vials (P less than 0.01). These results indicate that high-speed roller method at 64 h postinoculation, while only 24 of 41 (58%) were IP positive with shell vials (P less than 0.01). These results indicate that high-speed rolling is better than the shell vial technique for the detection of herpes simplex virus by IP staining.

Comparison of immunoblotting with other serological methods and virus isolation for the early detection of primary cytomegalovirus infection in allograft recipients

Sequential specimens from nine allograft recipients were examined by using a variety of methods to detect primary cytomegalovirus (CMV) infection as rapidly as possible posttransplantation. Sera were examined for immunoglobulin G (IgG) and IgM antibodies by immunoblotting, enzyme immunoassay, and immunofluorescence and also by complement fixation, latex agglutination, and an immunofluorescence test for antibody to CMV early antigen. Urine and occasionally blood, tissue, and other specimens were centrifuged onto cell cultures to enhance CMV infectivity. Eight of the nine patients showed laboratory evidence of primary CMV infection, and CMV was isolated from seven of the eight: in no case was virus isolated before seroconversion had become evident. However, serological tests differed in their abilities to detect antibody response to CMV infection in different patients; while immunoblotting, latex agglutination, and enzyme immunoassay for IgG antibodies generally detected seroconversion before complement fixation, this was not invariably the case. At present, optimal laboratory detection of CMV infections in these patients can be achieved only by a combination of serological methods and virus isolation.

Detection of influenza virus by centrifugal inoculation of MDCK cells and staining with monoclonal antibodies

Two methods for detection of influenza virus in 451 clinical respiratory specimens were compared: (i) 24-well-plate centrifugation with Madin-Darby canine kidney (MDCK) cells and staining with monoclonal antibody pools to influenza viruses A and B (Centers for Disease Control, Atlanta, Ga.) in an indirect immunofluorescence assay after incubation for 40 h, and (ii) conventional tissue cell culture with primary monkey cells and hemadsorption. For 100 of these specimens, direct examination of smears by the direct fluorescence assay with monoclonal antibodies (Boots Cell Tech/API Analytab Products, Plainview, N.Y.) was also performed. Influenza A virus was recovered from 28 specimens by tissue cell culture after incubation for an average of 4.75 days (range, 2 to 14 days). Influenza B virus was recovered from 35 specimens by tissue culture after incubation for an average of 5.4 days (range, 3 to 14 days). By the centrifugation assay, 23 specimens were positive for influenza A virus and 30 were positive for influenza B virus. All specimens positive by the centrifugation assay were also positive by conventional tissue cell culture. The sensitivities of the centrifugation assay were 82% for detection of influenza A virus and 86% for influenza B virus (84% overall); the specificity of the assay was 100%. Of the 100 specimens studied by direct examination, 15 were positive for influenza virus by both conventional culture and centrifugation assay; however, the direct-smear results for these 15 specimens were negative in 13 cases and inconclusive in 2. The centrifugation assay is a rapid and specific method for detection of influenza A and B viruses in clinical specimens, and it can serve as a valuable and cost-efficient adjunct to conventional culture methods.

Effect of age of shell vial monolayers on detection of cytomegalovirus from urine specimens

The effect of age of MRC-5 cell monolayers in shell vials on the detection of cytomegalovirus (CMV) from urine was evaluated. When the AD169 strain of CMV was used, 8-day-old monolayers had a higher mean count of fluorescent foci than 15-day-old monolayers did (5.78 versus 2.86) (P less than 0.02) and were more frequently positive (21 of 23 shell vials versus 14 of 22 shell vials) (P less than 0.04). Commercial shell vials used for clinical specimens were evaluated in groups of 8- to 11-, 12- to 15-, and 8- to 15-day-old monolayers. When compared with laboratory-prepared shell vials ranging in age from 3 to 9 days, commercial shell vials had a lower number of fluorescent foci in all groups (P less than 0.03, P less than 0.0001, and P less than 0.0001, respectively), the 12- to 15- and 8- to 15-day-old groups were less frequently positive (P less than or equal to 0.02 and P less than 0.02, respectively), and all three groups were more susceptible to the toxic effects of urine (P less than 0.0001, P less than 0.01, and P less than 0.0001, respectively). For all 191 specimens cultured (8- to 15-day-old group), one or both monolayers were destroyed in 60 (31.4%) specimens compared with 9 (4.7%) specimens toxic to laboratory-prepared shell vials (P less than 0.0001). Both the decreased sensitivity of older MRC-5 cells and the increased sensitivity to the toxic effects of urine made commercial shell vial less sensitive than laboratory-prepared shell vials for the detection of CMV.

Multisite evaluation of a monoclonal antibody reagent (Syva) for rapid diagnosis of cytomegalovirus in the shell vial assay

A pre-cytopathic effect (CPE) monoclonal antibody reagent (Syva Co., Palo Alto, Calif.) was evaluated in four laboratories for the rapid detection of cytomegalovirus (CMV) in shell vial cell cultures at 16 to 24 h and 40 to 48 h postinoculation. Results were compared with those obtained by inoculation of the specimen into conventional tube cell cultures that were examined for the presence of typical CMV CPE and subsequently tested by reaction with the monoclonal antibody reagent in an indirect immunofluorescence test. Of 937 specimens, CMV was positive in 184 (20%). CMV was detected twice as frequently in shell vials only (n = 29) as in conventional tube cell cultures (n = 14). Pre-CPE shell vial assay was 91% sensitive (range, 84 to 98%) and 96% specific (range, 93 to 98%) compared with the detection of CPE in conventional tube cell cultures. Overall, 137 of 166 (83%) and 143 of 166 (86%) of the CMV strains were detected at 16 to 24 h and 40 to 48 h postinoculation, respectively. The Syva reagent produced sensitive and specific results for the rapid detection of CMV infection in shell vial cell cultures and reliably confirmed the presence of the virus as detected by CPE in conventional tube cell cultures.

Rapid 24-well plate centrifugation assay for detection of influenza A virus in clinical specimens

Two methods for detection of influenza virus in 234 clinical respiratory specimens were compared: (i) a 24-well plate-centrifugation assay using Madin Darby canine kidney (MDCK) cells and staining with monoclonal antibody pools to influenza A and B (Centers for Disease Control, Atlanta, GA) after incubation for 16 h and 40 h, and (ii) conventional tube cell culture using MDCK cells and primary rhesus monkey kidney cells. Influenza A was identified in 23 specimens (10%). No influenza B was recovered. The rapid centrifugation and tissue culture methods were positive for influenza A in 21 (91%) and 16 (70%) of the 23 specimens, respectively. Fourteen specimens were positive by both methods, 2 were positive by tissue culture alone, and 7 were positive by rapid centrifugation only. Of the 21 specimens positive by rapid centrifugation, 16 (76%) were detected after overnight incubation, and 5 (24%) were positive only after incubation for 40 h. Cytopathic effect was observed in 13 (81%) of the 16 isolates identified by tissue culture after an average of 6 days, and 3 (19%) were identified only by hemadsorption and staining with monoclonal antibodies at day 10. Compared with conventional tissue culture, the 24-well plate centrifugation assay is a more rapid and more sensitive method for detecting influenza virus in clinical specimens.

Detection of herpes simplex virus in clinical specimens using a DNA probe after centrifugal inoculation of A549 cells

Two methods for detection of herpes simplex virus (HSV) in 216 clinical specimens were compared: (a) 24-well plate centrifugation using A-549 cells followed by nucleic acid hybridization (Ortho Diagnostic Systems, Inc., Raritan, NJ) after incubation for 16 to 18 h, and (b) conventional tube cell culture using A-549 cells. HSV was identified by conventional tube cell culture in 44 of 216 specimens (20%) and in 36 specimens (17%) by the centrifugation-hybridization method (P less than 0.01). HSV was recovered by tissue culture from all specimens positive by centrifugation-hybridization. The sensitivity, specificity, and positive and negative predictive values of the centrifugation-hybridization technique for detection of HSV in clinical specimens were 82, 100, 100, and 96%, respectively. Centrifugal inoculation of A549 cells in 24-well plates followed by nucleic acid hybridization after overnight incubation should not replace conventional tube cell culture for detection of HSV in clinical specimens.

Detection of cytomegalovirus DNA in short term cultures

Detection of human cytomegalovirus (CMV) by in situ DNA hybridisation six days after incubation of human diploid fibroblasts (ISDH-6) was evaluated prospectively in 205 urine samples, obtained from 57 kidney transplant and 17 bone marrow transplant recipients. The results were compared to those of conventional virus isolation (CVI) and the detection of CMV early antigens after one day of cultivation (EA-1). Of 42 samples positive for CMV by at least one of these methods, 40 (95%) were detected with ISDH-6. Thirty-five (83%) and 34 (81%) positive samples were found with CVI and EA-1, respectively. These data indicate that ISDH-6 is a sensitive method for detection of CMV. It can be used as a rapid and sensitive alternative to CVI in combination with EA-1.

Diagnosis of cytomegalovirus infection by detection of the early antigen of cytomegalovirus in cell cultures

Conventional virus isolation and detection of cytomegalovirus (CMV) early antigen by immunofluorescence staining of cultured cells were compared in the diagnosis of CMV infection from urine specimens. By virus isolation, 33 specimens out of 333 studied were positive, and the mean length of culturing time for a positive result was 23 days (range from 6 to 45 days). By early antigen detection, 35 specimens were positive after 20 hours in culture, but the number of positive findings increased to as high as 49 after 7 days in culture. It is recommended that, in addition to the early antigen staining after one day in culture, cells should also be stained after one week in culture, because the sensitivity is essentially improved by extended culturing time.

The effect of dexamethasone on the detection of cytomegalovirus in tissue culture and by immunofluorescence

With the development of both monoclonal antibodies to the immediate early nuclear antigen (EA) of cytomegalovirus (CMV) and different methods used for its detection, the time required for diagnosis of infection has become significantly shorter. However, discrepancies between tissue culture (TC) and the EA assay methods have raised questions concerning which method is more sensitive and whether a positive test result truly represents infection or latency. We have found that dexamethasone (Dex), when incorporated into the growth medium at a concentration of 10(-5) M, decreases the variability between the two techniques and increases the sensitivities of both TC and EA assay. However, for Dex to be effective, it was necessary to prepare, seed and grow the indicator cells in the presence of 10(-5) M Dex. Additionally, the cells had to be in contact with Dex for approximately 24 h before any effect was observed. Except for this step, all other procedures were the same as have been described elsewhere. In this study, four methods were compared: TC, TC with Dex (TC-D), EA, and EA with Dex (EA-D). Of 251 clinical specimens (200 microliter/well), 46 (18%) were positive for CMV. Of the 46, 30 (65%) were positive by TC, 39 (85%) by TC-D, 39 (85%) by EA, and 42 (91%) by EA-D. Without Dex the combination of TC plus EA detected only 41 of 46 (84%) positive samples. In contrast, the presence of Dex allowed detection of all 46 positive samples by TC-D and EA-D. Also, more fluorescent forming units (FFU) were detected by EA-D than EA (mean 14.8 FFU), and cytopathic effect was detected sooner (mean 9 days) by TC-D than by TC. Dex significantly increased the detection of CMV by TC (P less than 0.05). In addition, the use of any one of these methods alone did not effectively detect all positive samples. We suggest the combination of TC-D and EA-D for detection of all samples positive for CMV and to detect other viruses that may be missed by the EA method.

Effect of high-speed rolling on herpes simplex virus detection and replication

We examined the effect of high-speed rolling on herpes simplex virus replication. Inoculated cultures were rolled at 2, 96, or 383 rpm, while stationary cultures served as controls. At 24 h, inoculated cultures rolled at 96 rpm had a 6.8-fold increase in foci when compared with stationary cultures (P less than 0.01) and a 2.8-fold increase over cultures rolled at 2 rpm (P less than 0.05). Cultures rolled at 2 rpm had a 2.4-fold increase in foci over stationary cultures (P less than 0.05). Viral yield results correlated with focus results. Significantly more virus was present in cultures rolled at 96 rpm (7.3-fold) than in stationary cultures. Cultures rolled at 2 rpm produced 2.9-fold more virus than stationary cultures (P less than 0.05). Of 37 cultures rolled at 96 rpm, 33 (89%) were cytopathic effect positive at 96 h, while 18 of 40 (45%) were positive at 2 rpm and only 2 of 37 (5%) were positive for stationary cultures (P less than 0.01). Cultures rolled at 96 rpm produced maximum viral yields 2 days sooner than stationary cultures. Rolling of inoculated cultures should be used in the clinical laboratory to aid in the rapid detection of herpes simplex virus.

Chronic cytomegalovirus infection

Cytomegalovirus infects about 60% of persons in developed countries and may cause significant disease in immunosuppressed patients. Serology has no role in the diagnosis of CMV disease in such patients yet detection of the virus in diseased parts of the body can be used to monitor the course of disease and antiviral measures. Detection of viral proteins (alpha or beta proteins) by monoclonal antibodies in cell cultures infected by urine, saliva or blood samples from patients allows a positive diagnosis within 24 h (DEAFF test). Monoclonal antibodies against CMV can also be used to stain cells obtained directly from the infected patients.

Detection of cytomegalovirus in bronchial lavage and urine using a monoclonal antibody to an HCMV early nuclear protein

Laboratory diagnosis of 24 cases of human cytomegalovirus (HCMV) infection in patients with the acquired immunodeficiency syndrome, renal transplant recipients and premature infants was achieved. These results were obtained by a rapid, sensitive and versatile HCMV-antigen detection method, which combined cell culture and immunoperoxidase staining with a monoclonal antibody to an HCMV "early" nuclear protein. The results were compared with HCMV isolation by the conventional cell culture method. While some of these immunocompromised patients lacked a significant antibody response, infective HCMV could be detected in the patients' urine and bronchial lavage fluid. The diagnostic procedure took no longer than 24 h. The usefulness of this antigen test for an effective diagnosis in immunocompromised individuals was demonstrated. We recommend routine analysis of various specimens, since recent developments in chemotherapy of HCMV infection and the risks of long-term damage demand immediate management of the patients concerned.

Detection of adenovirus by rapid 24-well plate centrifugation and conventional cell culture with dexamethasone

Two methods for rapid detection of adenovirus were tested: (i) 24-well plate centrifugation followed by staining with a monoclonal antibody after incubation for 24 h and 48 h, and (ii) pretreatment of A549 cells used in conventional cell culture and 24-well plate centrifugation with 10(-5)M dexamethasone. Twenty-seven clinical isolates of adenovirus and 12 specimens from which adenovirus had been recovered were included in the analysis. Both isolates and specimens had been frozen at -70 degrees C for up to 6 months. By 24-well plate centrifugation both with and without dexamethasone, 21 (78%) and 27 (100%) isolates were positive for adenovirus at 24 h and 48 h, respectively. Of the specimens, 6 (50%) and 8 (67%) were positive by 24-well plate centrifugation without dexamethasone at 24 h and 48 h, respectively, whereas with dexamethasone 3 (25%) were positive at 24 h and 7 (58%) were positive at 48 h. Overall, combining isolates and specimens, the sensitivity of 24-well plate centrifugation for detection of adenovirus at 24 h was 69% without dexamethasone and 62% with dexamethasone, and at 48 h the sensitivity was 90% without dexamethasone and 87% with dexamethasone. The specificity under all conditions tested was 100%. In conventional tissue culture dexamethasone inhibited recovery of adenovirus. Without dexamethasone, adenovirus was recovered from all 39 samples within 7 days after inoculation; however with dexamethasone pretreatment, the virus was detected in only 31 (79%) of the samples tested in the same period of time.

Effect of dexamethasone on detection of herpes simplex virus in clinical specimens by conventional cell culture and rapid 24-well plate centrifugation

During a 4-month period, two methods for rapid detection of herpes simplex virus (HSV) were examined: (i) pretreatment of A549 cells with dexamethasone for conventional tissue culture (277 specimens) and (ii) 24-well plate centrifugation using A549 cells with and without dexamethasone pretreatment and staining with serotype-specific monoclonal antibodies (Syva Co., Palo Alto, Calif.) after incubation for 16 to 18 h (153 specimens). By conventional tube cell culture, both with and without dexamethasone, HSV was identified in 88 of 277 (32%) specimens. Significantly more specimens were positive for HSV at 24 h (46 versus 27 specimens) and at 48 h (a total of 72 versus 59 specimens) (P less than 0.0001) in dexamethasone-treated A549 cells. Of the 153 specimens tested by conventional culture and 24-well plate centrifugation, HSV was detected in 44 (29%) by conventional culture, and by 24-well plate centrifugation with and without dexamethasone, HSV was detected in 32 (21%) and 30 (20%) specimens, respectively. The sensitivity, specificity, and positive and negative predictive values of 24-well plate centrifugation with A549 cells for detection of HSV were 73 (71% without dexamethasone), 100, 100, and 90%, respectively. In conventional tube cell culture, pretreatment of A549 cells with dexamethasone results in more rapid detection of HSV. Centrifugal inoculation of dexamethasone-treated and untreated A549 cells in 24-well plates and staining with monoclonal antibodies after incubation for 16 to 18 h is an insensitive means to detect HSV in clinical specimens and should not replace conventional tube cell culture.

Effect of treatment of shell vial cell cultures with dimethyl sulfoxide and dexamethasone for detection of cytomegalovirus

Urine specimens submitted for the diagnosis of cytomegalovirus infection were inoculated into shell vials that had been pretreated with a combination of dimethyl sulfoxide (DMSO) and dexamethasone (DEX). The results were compared with those for inoculated shell vials which had received no drug treatment. Of 664 specimens, 100 (15%) were positive for cytomegalovirus. Of the 100 strains of cytomegalovirus, 88 (88%) were detected in both DMSO-DEX-treated and untreated shell vials. Of the remaining 12 positive specimens, 6 were detected with untreated shell vials exclusively and 6 were detected with DMSO-DEX-treated shell vials alone (not significant by the sign test). The median number of fluorescent foci was not significantly higher in DMSO-DEX-treated shell vials compared with that in untreated cultures (Wilcoxon signed-rank test; P = 0.1). DMSO-DEX-treated monolayers did not enhance the sensitivity detection of cytomegalovirus in shell vial cell cultures.