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

Specialization for Cell-Free or Cell-to-Cell Spread of BAC-Cloned Human Cytomegalovirus Strains Is Determined by Factors beyond the UL128-131 and RL13 Loci

It is widely held that clinical isolates of human cytomegalovirus (HCMV) are highly cell associated, and mutations affecting the UL128-131 and RL13 loci that arise in culture lead to the appearance of a cell-free spread phenotype. The bacterial artificial chromosome (BAC) clone Merlin (ME) expresses abundant UL128-131, is RL13 impaired, and produces low infectivity virions in fibroblasts, whereas TB40/e (TB) and TR are low in UL128-131, are RL13 intact, and produce virions of much higher infectivity. Despite these differences, quantification of spread by flow cytometry revealed remarkably similar spread efficiencies in fibroblasts. In epithelial cells, ME spread more efficiently, consistent with robust UL128-131 expression. Strikingly, ME spread far better than did TB or TR in the presence of neutralizing antibodies on both cell types, indicating that ME is not simply deficient at cell-free spread but is particularly efficient at cell-to-cell spread, whereas TB and TR cell-to-cell spread is poor. Sonically disrupted ME-infected cells contained scant infectivity, suggesting that the efficient cell-to-cell spread mechanism of ME depends on features of the intact cells such as junctions or intracellular trafficking processes. Even when UL128-131 was transcriptionally repressed, cell-to-cell spread of ME was still more efficient than that of TB or TR. Moreover, RL13 expression comparably reduced both cell-free and cell-to-cell spread of all three strains, suggesting that it acts at a stage of assembly and/or egress common to both routes of spread. Thus, HCMV strains can be highly specialized for either for cell-free or cell-to-cell spread, and these phenotypes are determined by factors beyond the UL128-131 or RL13 loci.IMPORTANCE Both cell-free and cell-to-cell spread are likely important for the natural biology of HCMV. In culture, strains clearly differ in their capacity for cell-free spread as a result of differences in the quantity and infectivity of extracellular released progeny. However, it has been unclear whether "cell-associated" phenotypes are simply the result of poor cell-free spread or are indicative of particularly efficient cell-to-cell spread mechanisms. By measuring the kinetics of spread at early time points, we were able to show that HCMV strains can be highly specialized to either cell-free or cell-to-cell mechanisms, and this was not strictly linked the efficiency of cell-free spread. Our results provide a conceptual approach to evaluating intervention strategies for their ability to limit cell-free or cell-to-cell spread as independent processes.

New 2-Oxoimidazolidine Derivatives: Design, Synthesis and Evaluation of Anti-BK Virus Activities in Vitro

A series of novel 2-oxoimidazolidine derivatives were synthesized and their antiviral activities against BK human polyomavirus type 1 (BKPyV) were evaluated in vitro. Bioassays showed that the synthesized compounds 1-{[(4E)-5-(dichloromethylidene)-2-oxoimidazolidin-4-ylidene]sulfamoyl}piperidine-4-carboxylic acid (5) and N-Cyclobutyl-N'-[(4E)-5-(dichloromethylidene)-2-oxoimidazolidin-4-ylidene]sulfuric diamide (4) exhibited moderate activities against BKPyV (EC₅₀ =5.4 and 5.5 μm, respectively) that are comparable to the standard drug Cidofovir. Compound 5 exhibited the same cytotoxicity in HFF cells and selectivity index (SI₅₀ ) as Cidofovir. The selectivity index of compound 4 is three times less than that of Cidofovir due to the higher toxicity of this compound. Hence, these compounds may be taken as lead compound for further development of novel ant-BKPyV agents.

In vitro toxicity and efficacy of verdinexor, an exportin 1 inhibitor, on opportunistic viruses affecting immunocompromised individuals

Infection of immunocompromised individuals with normally benign opportunistic viruses is a major health burden globally. Infections with viruses such as Epstein-Barr virus (EBV), human cytomegalovirus (HCMV), Kaposi's sarcoma virus (KSHV), adenoviruses (AdV), BK virus (BKPyV), John Cunningham virus (JCPyV), and human papillomavirus (HPV) are significant concerns for the immunocompromised, including when these viruses exist as a co-infection with human immunodeficiency virus (HIV). These viral infections are more complicated in patients with a weakened immune system, and often manifest as malignancies resulting in significant morbidity and mortality. Vaccination is not an attractive option for these immune compromised individuals due to defects in their adaptive immune response. Verdinexor is part of a novel class of small molecules known as SINE (Selective Inhibitor of Nuclear Export) compounds. These small molecules demonstrate specificity for the nuclear export protein XPO1, to which they bind and block function, resulting in sequestration of XPO1-dependent proteins in the nucleus of the cell. In antiviral screening, verdinexor demonstrated varying levels of efficacy against all of the aforementioned viruses including previously with HIV. Studies by other labs have discussed likely mechanisms of action for verdinexor (ie. XPO1-dependence) against each virus. GLP toxicology studies suggest that anti-viral activity can be achieved at a tolerable dose range, based on the safety profile of a previous phase 1 clinical trial of verdinexor in healthy human volunteers. Taken together, these results indicate verdinexor has the potential to be a broad spectrum antiviral for immunocompromised subjects for which vaccination is a poor option.

Diversity, drug resistance, and the epidemic of subtype C HIV-1 in Africa

The human immunodeficiency virus (HIV) infection/acquired immunodeficiency syndrome (AIDS) epidemic has grown from a handful of sentinel observations in New York and California, nearly 25 years ago, to an epidemic that has claimed 500,000 lives in the United States and >20 million worldwide. Tom Merigan's scientific career led him to focus on viral pathogenesis as translational "bench-to-bedside" research, aimed squarely at the development of antiretroviral treatment. As a founder and leader of the AIDS Clinical Trials Group, Tom played a pivotal role in the national response to HIV. He led the development of a succession of antiretroviral drugs, their combined use, and the introduction of new methods for monitoring HIV infection. The current response to the global epidemic and the tools now coming to bear on diagnosis, treatment, and monitoring owe much to Tom's relentless pursuit of excellence in research and the training he offered generations of clinical virologists and infectious disease physicians.

Analysis of the human cytomegalovirus genomic region from UL146 through UL147A reveals sequence hypervariability, genotypic stability, and overlapping transcripts

BACKGROUND

Although the sequence of the human cytomegalovirus (HCMV) genome is generally conserved among unrelated clinical strains, some open reading frames (ORFs) are highly variable. UL146 and UL147, which encode CXC chemokine homologues are among these variable ORFs.

RESULTS

The region of the HCMV genome from UL146 through UL147A was analyzed in clinical strains for sequence variability, genotypic stability, and transcriptional expression. The UL146 sequences in clinical strains from two geographically distant sites were assigned to 12 sequence groups that differ by over 60% at the amino acid level. The same groups were generated by sequences from the UL146-UL147 intergenic region and the UL147 ORF. In contrast to the high level of sequence variability among unrelated clinical strains, the sequences of UL146 through UL147A from isolates of the same strain were highly stable after repeated passage both in vitro and in vivo. Riboprobes homologous to these ORFs detected multiple overlapping transcripts differing in temporal expression. UL146 sequences are present only on the largest transcript, which also contains all of the downstream ORFs including UL148 and UL132. The sizes and hybridization patterns of the transcripts are consistent with a common 3'-terminus downstream of the UL132 ORF. Early-late expression of the transcripts associated with UL146 and UL147 is compatible with the potential role of CXC chemokines in pathogenesis associated with viral replication.

CONCLUSION

Clinical isolates from two different geographic sites cluster in the same groups based on the hypervariability of the UL146, UL147, or the intergenic sequences, which provides strong evidence for linkage and no evidence for interstrain recombination within this region. The sequence of individual strains was absolutely stable in vitro and in vivo, which indicates that sequence drift is not a mechanism for the observed sequence hypervariability. There is also no evidence of transcriptional splicing, although multiple overlapping transcripts extending into the adjacent UL148 and UL132 open reading frames were detected using gene-specific probes.

Utility of liver biopsy culture in pediatric liver transplant recipients

The purpose of our study was to determine the utility of the practice of culturing percutaneous liver biopsy specimens obtained from pediatric LT recipients for evaluation of fever and/or elevated serum aminotransferases. Accordingly, a retrospective analysis was done of the 101 liver biopsies obtained during an eight-year period which had been submitted for bacterial, fungal and/or viral culture (out of a total of 174 biopsies in 38 patients). The purpose of the analysis was to ask three questions. (1) What organisms were cultured? (2) Were there clinical profiles that were characteristic of the type of organism? (3) Was the practice cost-effective? The analysis indicated that 34/86 biopsy cultures were positive for bacteria, 4/75 for fungus and 2/81 for virus. Clinical and laboratory data for children with cultures positive for enteric flora (n = 9) were compared to those with cultures positive for Gram-positive organisms (n = 17), laboratory contaminants (n = 8), and those with negative cultures (n = 52). Children with biopsies positive for enteric flora had a 'cholestatic profile': mean direct bilirubin 7 mg/dl, ALT 78 IU/l, direct bilirubin/ALT 0.09, in comparison to children with biopsies positive for Gram-positive flora. These children had a 'hepatocellular profile': mean direct bilirubin 4 mg/dl, ALT 332 IU/l, direct bilirubin/ALT 0.01 (p = 0.04 versus the enteric flora values) and a high percentage of polymorphonuclear leukocytes (mean 69% versus 38% for those with negative cultures, p = 0.001.) The charge for performing each bacterial culture was $28 (total $28 x 86 = $2408: $268 per enteric flora-positive biopsy; $93 per biopsy positive for either enteric flora or Gram-positive flora). The charge for each fungal culture was also $28 (total $28 x 75 = $2100: $525 per positive culture), while the cost for each viral culture was $140 (total $140 x 81 = $11,340: $5670 per positive culture). Thus, discounting the eight cultures positive for laboratory contaminants, a total of $15,848 was spent for 32 positive cultures. Given the high cost of liver transplantation, this information suggests that discretion should be used in submission of liver biopsy samples for culture in pediatric transplant patients. We recommend that when liver biopsies are performed for evaluation of elevated serum aminotransferases and/or fever, culture of biopsy specimens for bacteria should be considered in children with a 'cholestatic profile': direct bilirubin > or = 7 mg/dl and direct bilirubin/ALT > 0.08, or a 'hepatocellular profile': direct bilirubin < or = 4 mg/dl and direct bilirubin/ALT < 0.05, together with polymorphonuclear leukocytes > 70%. Following these guidelines might provide valuable information pertinent to patient management (especially since Gram-negative organisms can sometimes be cultured from the liver and not from blood) while reducing costs. Fungal cultures should be restricted to critically ill children. However, our data suggest that the practice of obtaining fungal and viral cultures of the liver in most pediatric transplant patients has an unacceptably high cost/benefit ratio, particularly since recovery of the organism from the peripheral blood is likely.

Optimisation of the polymerase chain reaction and dot-blot hybridisation for detecting cytomegalovirus DNA in urine: comparison with detection of early antigen fluorescent foci and culture

Rapid, sensitive and specific assays are required for the diagnosis of CMV infection following transplantation. We describe our experience in developing assays for detecting CMV in urine. Conventional preparation of probes cloned after amplification in E. coli led to contamination with E. coli nucleic acids; these hybridised to E. coli DNA present in urine and produced false positive results. Two CMV probes (Hind III and gL) hybridised to human DNA despite high stringency; these probes were thus unsuitable for detecting viral nucleic acids in clinical samples. A PCR derived probe from the immediate early gene of CMV detected dot-blotted CMV DNA specifically. Optimal preparation of urine for detection of CMV DNA was as follows; four freeze/thaw cycles and ultracentrifugation before in vitro proteinase K/SDS treatment, phenol:chloroform extraction, heat denaturation and direct application onto a nylon membrane. However, dot-blot hybridisation was a poor test for CMV in urine; it had low sensitivity and specificity compared with virus isolation and DEAFF. Single round PCR of a 293 bp region of CMV DNA was sensitive and specific to CMV targets. However, undiluted urine contained PCR inhibitors that could only be partly removed by using PEG precipitation. PCR of CMV DNA from urine was specific but was insensitive compared to conventional culture and DEAFF. A significant proportion of urine samples were toxic in conventional culture and DEAFF tests but, PCR of CMV DNA from urine is insensitive and despite its specificity is unlikely to be advantageous in clinical practice even when DEAFF or culture prove unreliable.

Congenital cytomegalovirus infection

OBJECTIVE

Congenital cytomegalovirus is the most common viral infection affecting approximately 1% of newborns. The virus can be transmitted to the fetus during both primary and recurrent infection. Although most of the infants are asymptomatic at birth, up to 15% develop late complications. The annual cost of treating cytomegalovirus infection complications in the USA is two billion US dollars. Many issues regarding cytomegalovirus infection such as routine screening, antenatal diagnosis and vaccination during pregnancy are unsettled and disputed. The aim of this article is to review the current literature on the subject and to draw some conclusions.

DESIGN

Review of the current literature.

CONCLUSIONS

At present, it appears that there is no indication for routine prenatal screening, while other issues, such as the most accurate method for antenatal diagnosis and the indications for pregnancy termination are, as yet, unsettled.

Preparation of a specific RNA probe for detection of Mycobacterium paratuberculosis and diagnosis of Johne's disease

A species-specific recombinant clone (F57) was obtained from a genomic library of Mycobacterium paratuberculosis in the transcription vector pGem 3Z. This clone proved to be specific for all mycobacteria tested, including M. avium, and was able to recognize all of the tested M. paratuberculosis strains isolated from animals and humans (patients with Crohn's disease). The F57 insert was sequenced and a segment of 620 bp with a G + C content of 58.9% was identified. Comparison of the sequence with sequences in the EMBL and UGEN data banks revealed the uniqueness of the F57 sequence, which had no resemblance to other known genes.

HCMV-DNA is detected more frequently than infectious virus in blood leucocytes of immunocompromised patients: a direct comparison of culture-immunofluorescence and PCR for detection of HCMV in clinical specimens

In two studies comparing detection of human cytomegalovirus (HCMV) in 118 patients (93 of whom were immunocompromised) by the polymerase chain reaction (PCR) and virus isolation using either early antigen detection by culture-immunofluorescence or conventional cytopathic effect, DNA-PCR was found to be the most sensitive, followed by culture-immunofluorescence, then by cytopathic effect. Urine was inhibitory to the action of Taq polymerase; this was overcome by concentration of HCMV with PEG 6000 prior to gene amplification. Without PEG treatment, HCMV-DNA in 6 of the 11 specimens positive by culture-immunofluorescence was not detectable by PCR. In healthy seropositive individuals, HCMV-DNA was not detected in leucocytes. However, in immunocompromised patients with AIDS or transplants, and therefore at high risk of HCMV infection or reactivation, blood leucocytes were usually positive for HCMV-DNA (19/20), some for as long as 20 weeks after initial detection and persisting for long after culture-immunofluorescence became negative. Neither HCMV-RNA nor infectious HCMV were detected in the follow-up blood leucocyte specimens from immunocompromised patients who had detectable HCMV-DNA in these cells. These data suggest that persistence of HCMV-DNA in blood leucocytes of immunocompromised patients after reactivation or primary infection may be due to persistence of non-viable virus, residual HCMV genomic DNA, or latent HCMV-DNA.

Detection of human cytomegalovirus in plasma of AIDS patients during acute visceral disease by DNA amplification

By using the polymerase chain reaction (PCR) amplification procedure, 19 (83%) of 23 plasma specimens obtained from individuals with AIDS and human cytomegalovirus (HCMV) visceral disease were found to be positive for plasma viremia as detected by PCR (PV-PCR), whereas 78% of cultures of peripheral blood leukocytes from the same samples were found to be positive. All 11 specimens prospectively obtained from individuals with acute HCMV disease were positive by PV-PCR. Plasma specimens from patients who received ganciclovir therapy rapidly became both culture and PV-PCR negative, and there was an excellent correlation between the two procedures. DNA detected by PV-PCR was unaffected by filtering plasma through a 0.2-microns-pore-size filter, although a conserved cellular gene, HLA-DQ alpha, was undetectable by PCR following filtration. HCMV DNA in plasma could be quantitated by PV-PCR by using endpoint serial dilutions, with detectable virus being present in 10(1) to 10(-2) microliters of plasma. A low titer of infectious virus could be detected in 2 of 11 plasma samples. The detection of HCMV DNA in plasma by PV-PCR promises to be a useful procedure for monitoring patients with AIDS suspected of having impending, acute, or recurrent HCMV visceral disease and suggests an additional route by which virus may disseminate in the immunocompromised host.

Diagnosis of cytomegalovirus infection: a review

Images

Nonpulmonary manifestations of cytomegalovirus infection in immunocompromised patients

Nonpulmonary manifestations of cytomegalovirus (CMV) infection in immunocompromised patients include chorioretinitis, gastrointestinal infection, and central nervous system disease. Diagnosis of end organ disease, especially in the gastrointestinal tract, is best substantiated by histologic evidence of CMV inclusions. Positive cultures of CMV provide evidence for supporting infection but do not define actual end organ disease. Satisfactory treatment of the disease can be accomplished with ganciclovir or foscarnet, although these agents only suppress virus replication. In many instances, severe CMV-induced end organ disease in immunocompromised patients will progress despite treatment. In some instances, resistance to the antiviral agent is the basis for drug failure. Patients at high risk for CMV disease can be identified, and studies of prophylaxis are in progress.

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.

Rejection, herpesvirus infection, and Ki-67 expression in endomyocardial biopsy specimens from heart transplant recipients

We examined 164 endomyocardial biopsy specimens from 29 patients who received an orthotopic heart transplant since 1984. Rejection was graded according to the Hannover classification. Non-isotopic in situ DNA hybridization was conducted on cryostat sections with biotinylated probes for herpes simplex virus, Epstein-Barr virus, and cytomegalovirus. Serial sections of 126 biopsies were investigated immunohistochemically for the presence of activated T lymphocytes and proliferating cells, with monoclonal antibodies against interleukin 2 receptors (CD 25) and Ki-67 antigen. Relations between rejection grades, presence of proliferating cells, and presence of herpesvirus DNA were determined for the total number of biopsies. For some patients correlation of these parameters was studied over time. Herpesviral nucleic acids were detected in 25% of all biopsies: 37% of biopsies with relevant rejection (grades A 2 or A 3; 39% of all biopsies) compared to 18% of biopsies graded A 0, A 1, or A 5 (61% of all samples) (P less than 0.01). 56% of the biopsies with infection showed relevant rejection as compared with only 33% of the uninfected. Ki-67 expression was found in 41% of all biopsies, mainly in infiltrating cells: 69% of biopsies with relevant rejection compared with 23% of cases of minor/no rejection (P much less than 0.001). Ki-67 expression was also associated with herpesvirus infection: 66% of infected biopsies contained Ki-67 positive cells compared with 33% of uninfected biopsies (P less than 0.001). Herpesvirus infection was usually observed within the interstitial cell population, which, in many cases, displayed a considerable Ki-67 expression, too. In few cases only, hybridization was unequivocally found in vascular wall cells or myocytes. Viral myocarditis does not only mimic graft rejection morphologically, but it may also affect the course of rejection, via induction of antigenic changes or direct injury of cardiac tissues. Virus infections may also elicit or aggravate obliterative coronary artery disease, and thus contribute to accelerated graft atherosclerosis.

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.

Cytomegalovirus DNA detection of an immediate early protein gene with nested primer oligonucleotides

A rapid and sensitive polymerase chain reaction (PCR) was developed to detect conserved sequences from the immediate early gene of human cytomegalovirus (HCMV). The primers sequences were from EcoRI J fragment of Ad169. The first primer set was selected to amplify a 242 bp fragment and the next primer set was nested within the first and amplified a 146 bp fragment. With the single PCR system it was possible to detect 100 fg HCMV DNA but with double PCR 5-10 fg were detectable. Specific amplification was seen in urines from patients with HCMV infections. 20 urine samples were analysed by single PCR, double PCR and virus cultivation. The double PCR was the most sensitive method. Urines from healthy seropositive persons and cells infected with other members of the herpes virus family were negative with all three methods. This suggests that specific amplification by double PCR is sensitive and can be used for rapid detection of HCMV DNA in cases with activated infection.

Sensitive non-isotopic DNA hybridisation assay or immediate-early antigen detection for rapid identification of human cytomegalovirus in urine

A sensitive non-radioactive DNA hybridisation assay employing digoxigenin-labelled probes was compared with immediate-early antigen detection and conventional virus isolation for the identification of human cytomegalovirus (HCMV) in 249 urine samples. Of 44 specimens yielding HCMV by virus isolation, more were positive by DNA hybridisation (32; 73%) than by immediate-early antigen detection (25; 52%) (P = 0.05). The specificity of the hybridisation assay in 45 apparently falsely positive specimens was supported by detection of HCMV DNA in 40 of these specimens using the polymerase chain reaction. Many urine specimens may thus contain large amounts of non-viable virus or free viral DNA. Evaluation of various protocols for the extraction and denaturation of virus DNA prior to hybridisation showed that proteinase K digestion with phenol/chloroform extraction was the most sensitive and reliable procedure. We conclude that the non-radioactive DNA hybridisation assay described is a potentially valuable routine diagnostic test.

Generation and application of a monoclonal antibody raised against a recombinant cytomegalovirus-specific polypeptide

Procedures for diagnostics of cytomegalovirus infections include histopathology, cell culture, serology, and direct detection of viral antigens or nucleic acids within infected cells or tissues. In order to develop a new diagnostic reagent for viral antigen detection, we generated a mouse monoclonal antibody. This antibody was raised against a recombinant antigen representing part of the large phosphorylated structural protein pp150 of human cytomegalovirus. The monoclonal antibody was shown to be useful for antigen detection by immunofluorescence and immunoenzymatic staining in infected cells from cell culture as well as from infected organs. The antibody proved to be reactive even in paraffin-embedded sections from tissue specimens.

Quantitation of cytomegalovirus DNA by blot hybridization in blood leukocytes of viremic patients

We describe a technique for quantitation of viral DNA in blood leukocytes during viremic infection with human cytomegalovirus (CMV). Using a cloned subgenomic DNA probe and a blot hybridization assay, small amounts of viral DNA within samples of leukocyte DNA could be quantitated reproducibly using a videodensitometer. Critical components of the assay were: (1) a direct relationship between optical density and known amounts of viral DNA diluted in cellular DNA as positive standard samples and, (2) determination of the proper duration of autoradiographic exposure. The technique was sufficiently sensitive to detect 10 picograms of CMV DNA in the presence of microgram quantities of host cell DNA. In addition, samples containing minute amounts of CMV DNA could reliably be distinguished from samples that were negative. We have used the technique to characterize the pathogenesis of CMV viremia and to monitor the effects of antiviral chemotherapy. This procedure could easily be applied to pathogenetic studies of a variety of other infectious agents.

Cytomegalovirus-specific B cell activation as a potential marker for the diagnosis of cytomegalovirus infection

In vitro secretion of antibodies to cytomegalovirus was investigated by analysis of peripheral blood mononuclear cell culture supernatants from subjects infected with cytomegalovirus. Patients with primary or recurrent cytomegalovirus infection showed transient in vitro cytomegalovirus-specific antibody secretion. A high proportion of patients infected with human immunodeficiency virus and sero-positive for cytomegalovirus showed in vitro cytomegalovirus-specific antibody secretion. All peripheral blood mononuclear cell cultures from patients with symptomatic human immunodeficiency virus infection were found to secrete in vitro antibodies to cytomegalovirus, despite the fact that isolation of cytomegalovirus from some of these patients was not achieved. In human immunodeficiency virus-infected patients, in vitro secretion of anti-cytomegalovirus antibodies appeared to be persistent. In vitro cytomegalovirus-specific antibody secretion by peripheral blood lymphocytes probably reflects an in vitro cytomegalovirus-specific B cell activation. This new assay could be considered an interesting method for detecting both acute or chronic cytomegalovirus infection, with potential use in routine laboratory practice.

Rapid detection of cytomegalovirus DNA in urine samples with a dot blot hybridization immunoenzymatic assay

A dot blot hybridization immunoenzymatic assay for the rapid detection of cytomegalovirus DNA in urine samples was developed by using a digoxigenin-labeled probe which was immunoenzymatically visualized by antidigoxigenin Fab fragments labeled with alkaline phosphatase. A total of 516 urine samples from different groups of subjects were analyzed, and the hybridization assay was able to yield results within 24 h. The results obtained were compared with results for detection of cytomegalovirus antigens in infected cell cultures.

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 application of polymerase chain reaction to the detection of rotaviruses in faeces

An assay protocol based on exploiting the polymerase chain reaction (PCR) for the detection of rotavirus in infected faeces is described. The assay is 100,000 times more sensitive than the standard electropherotype method that is widely used. It also gives a 5000-fold increase in sensitivity over the hybridisation based assay previously developed (Pedley and McCrae, 1984) and does not require the use of radioisotopes. The amplified product is a full length c-DNA copy of the gene encoding the major neutralisation antigen of the virus whose molecular cloning and sequence analysis will allow detailed information on the molecular basis of epidemiological variation to be rapidly collected.

A simple and rapid procedure for the direct detection of cytomegalovirus in urine samples

We compared cytomegalovirus (CMV) isolation in tissue culture and viral DNA detection by DNA:DNA hybridization in 60 clinical urine samples concentrated by different procedures. Our results showed that urine concentration by filtration is the easiest and quickest procedure allowing further detection of CMV. With optimized working conditions, the CMV detection in urine can be done in 5 hr without requiring cell cultures or costly instruments.

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 infection after organ transplantation: an update with special emphasis on renal transplantation

Cytomegalovirus infections are still the most important infectious complications after organ transplantation. Besides historical notes this review will deal with new aspects concerning the epidemiology of the CMV, diagnostic modalities of CMV infection, the delicate counterbalance between the immune system and the CMV, as well as the symptomatology of this infection. Furthermore, aspects like prophylaxis and new, promising therapeutic regimes for treatment of infection will be dealt with. Although this update is applicable for all types of solid organ transplantation, emphasis will be on renal transplantation.

Antibodies to cytomegalovirus in renal allograft recipients: correlation with isolation of virus

A cohort of 47 renal transplant recipients was studied prospectively for up to one year after transplantation. Cytomegalovirus (CMV) was isolated from 21 of the patients. The first time the virus was isolated seven patients were IgM positive, nine showed a significant rise in IgG titres, and 12 had a four-fold or greater rise in complement fixation titre. There was no significant difference in the time at which virus was first detected following transplantation between patients with primary CMV infection and those with reinfection or recurrent infection. In general, patients with primary infection shed virus consistently over long periods. Those with reinfection or recurrent infection shed virus intermittently or not at all. There were considerable differences between individual patients in the timing and pattern of the immune response. Taken overall, a four-fold rise detected by the complement fixation test correlated best with the onset of CMV shedding in primary infection. There was more variation in the pattern of antibody response in cases of reinfection or recurrent infection, with no single serological test correlating better than the others. It is concluded that serology is of limited value in the detection of active CMV infection after renal transplantation.

Polymerase chain reaction and viral culture techniques to detect HSV in small volumes of cerebrospinal fluid; an experimental mouse encephalitis study

A technique is described for the detection of HSV-DNA in very small volumes (5-10 microliters) of cerebrospinal fluid (CSF). The method was evaluated in CSF samples of 4-6-week-old mice inoculated with HSV-1 via the corneal route. The sensitivity of the PCR assay was compared with results of spin-amplified viral culture with immunofluorescent visualization (SAC/IF), routine viral culture (RVC) and radioactive dot-blot hybridization (DBA) in CSF samples obtained from other mice. The results show the PCR to be superior over the other techniques: infectious virus or viral DNA in CSF was demonstrated by PCR, SAC/IF, RVC and DBA in 68, 55, 20 and 2.5%, respectively. These results show the feasibility of the PCR for a rapid, non-invasive diagnosis of human HSV-encephalitis.

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.

An improved immunocytochemical method for the detection of human cytomegalovirus antigens in peripheral blood leucocytes

A recently described immunoperoxidase method for the detection of nuclear human cytomegalovirus (HCMV) immediate early antigen (IEA) directly on peripheral blood leucocytes suffers from the drawback that the antigen is vulnerable to endogenous peroxidase inactivation procedures. To solve this problem a procedure is developed in which endogenous peroxidase is inactivated after binding and immobilization of the primary antibody with 4% formaldehyde. In combination with this procedure, three types of inactivation were investigated: glucose/glucose oxidase, hydrochloric acid and methanol/H2O2. Of these three, the first gives optimal results, especially in combination with methanol/acetic acid (20/1 v/v) as the primary fixative. This procedure results in preparations which allow for a more objective evaluation and enable automated examination using bright field microscopy. As a second improvement we developed a simple adherence method in order to diminish the risk of infection for the laboratory staff during processing of unknown blood samples. The protocol described shows great clinical potential for the diagnosis of HCMV infections.

BK virus (BKV) detection in urine specimens of immunocompromised patients: comparison between the DNA-DNA hybridization assay, the immunofluorescence test and the dot enzyme immunoassay

Three methods used for the detection of BK virus in urine specimens, the indirect immunofluorescence test, the dot enzyme immunoassay and the DNA-DNA hybridization assay, were compared by testing specimens from 49 immunocompromised patients. All three assays were effective in detecting BK virus. The technical advantage of each of them was discussed. The immunofluorescence test was found to be the simplest one to perform; the DNA-DNA hybridization assay displayed exquisite sensitivity; and the easy reading of the dot enzyme immunoassay did not require the specialized training inherent to immunofluorescence assays. The dot enzyme immunoassay might therefore be the most practical method for screening urine specimens of immunocompromised patients, especially when the sediment is poor in cells. Conversely, the indirect immunofluorescence test might be the method of choice for checking patients with haemorragic cystitis whose urine samples usually contain large amounts of cells.

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.

Use of synthetic oligodeoxyribonucleotides for type-specific identification of coxsackie B viruses

Synthetic oligodeoxyribonucleotides were used for type-specific identification of members of the coxsackie B virus group by nucleic acid hybridization. Two pairs of oligonucleotide chains were constructed based on nucleotide sequences in the VP1 regions of coxsackieviruses B3 and B4. Each labelled probe had a length of 24 nucleotides. The results showed that the oligonucleotide hybridized in a type-specific manner when assayed with extracts from cells infected with all different coxsackie B viruses. A method based on similar principles may thus be used for enterovirus typing.

Polymerase chain reaction assay for detection of human cytomegalovirus

Direct detection of human cytomegalovirus (HCMV) from clinical specimens was examined by using the polymerase chain reaction (PCR) for amplifying HCMV DNA. The efficiency of the amplification reaction was examined by using three different buffers and concentrations of deoxynucleotide triphosphates. The PCR assay was most efficient with a reaction mixture containing 17 mM ammonium sulfate, 67 mM Tris hydrochloride (pH 8.5), 7 mM MgCl2, 10 mM 2-mercaptoethanol, 170 micrograms of bovine serum albumin per ml, and each deoxynucleotide triphosphate at a final concentration of 1.5 mM. After 35 cycles of amplification, 0.15 fg of a plasmid containing the cloned target gene (corresponding to approximately six gene copies) was detected. The PCR assay correctly identified all of 24 clinical isolates of HCMV. Virus in urine specimens could be disrupted by heating at 93 degrees C for 30 min. The viral DNA was amplified directly from 5 microliters of preheated urine, with no further treatment before amplification. We tested the PCR assay on urine specimens from patients who had undergone renal transplantation that had been screened for the presence of HCMV by enzyme-linked immunosorbent assay, hybridization assay, and direct virus isolation. Specimens that were positive by one or more of these assays were screened by PCR. HCMV was consistently detected by PCR in all specimens that were positive by at least one other test. No cross-reactivity to other herpesviruses or MRC-5 cellular DNA was observed.

Primer-mediated enzymatic amplification of cytomegalovirus (CMV) DNA. Application to the early diagnosis of CMV infection in marrow transplant recipients

A nucleic acid amplification procedure, the polymerase chain reaction (PCR), has been used to establish a diagnostic assay for the identification of cytomegalovirus (CMV) immediate-early sequences in clinical specimens. Preliminary testing against virus-infected cell cultures indicated that the PCR assay was highly CMV-specific, recognizing both wild-type and laboratory strains of CMV. There was no cross-reactivity with human DNA or with DNA from other herpes viruses. The sensitivity of the assay, using cloned CMV AD169 Eco RI fragment-J as template, was 1 viral genome per 40,000 cells. In a prospective study of CMV infection in bone marrow transplant recipients, the PCR assay correctly identified four patients with confirmed CMV infection. In three of these patients who were followed longitudinally, correlation of DNA reactivity with CMV culture and CMV antibody status over time indicated that DNA was the most sensitive marker for the diagnosis of CMV infection.

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.

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.

Detection of cytomegalovirus from clinical specimens in centrifugation culture by in situ DNA hybridization and monoclonal antibody staining

An in situ DNA hybridization kit for cytomegalovirus (CMV) was evaluated for the detection of CMV in centrifugation culture. Of 61 clinical specimens, 17 (27.8%) were positive for CMV by monoclonal antibody staining following centrifugation. Of the 17 positive specimens, 15 were detected by DNA hybridization (24.5%). However, the earliest that CMV could be detected by DNA hybridization was 58 h as compared with 16 h with monoclonal antibodies following centrifugation. DNA hybridization remains of great interest for the study and detection of CMV infection. However, current DNA hybridization techniques are not sufficiently rapid to replace the use of monoclonal antibodies in centrifugation culture.

Rapid and accurate viral diagnosis

In recent years, there has been increased recognition of the importance of viral infections. In addition, new antiviral agents have become available. These factors have led to a marked increase in utilization of viral diagnostic services. In this review, both conventional and rapid methods for viral diagnosis are presented, with emphasis on recent advances. The antiviral agents currently available and the major drugs under investigation are also briefly discussed. It is hoped that this review will serve as a useful adjunct for the management of patients with virus infections.