Phase 1 trial evaluating MRG-106, a synthetic inhibitor of microRNA-155, in patients with cutaneous t-cell lymphoma (CTCL)

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Background: MRG-106 is an oligonucleotide inhibitor of miR-155, a microRNA with a strong mechanistic link to CTCL, selected based on its activity in mycosis fungoides (MF) cell lines. The objective of this first-in-human study is to evaluate the safety, tolerability, maximum tolerated dose (MTD), pharmacokinetics (PK), and preliminary efficacy of MRG-106 in MF patients. Methods: This Phase 1 trial employs a dose-escalation design to evaluate either intratumoral (IT, 75 mg/dose) or subcutaneous (SC, ≤ 900 mg/dose) administration of MRG-106. Patients were required to have biopsy-proven stage I-III MF and plaque- or tumor-stage lesions. Results: Fifteen patients (12M/3F, median age 59 years) have been dosed over 1-4 weeks. All patients tolerated the IT or SC administrations well with only minor local injection reactions in 8 patients. Thirteen of 15 patients completed dosing as scheduled. There were no clinically significant MRG-106 related adverse events with the exception of one grade 3 pruritus. The MTD has not yet been reached. In the IT cohort, a reduction of ≥50% in the baseline Composite Assessment of Index Lesion Severity (CAILS) score was observed in the MRG-106 treated lesions in all 4 evaluable patients who completed dosing; such responses were maintained to the End of Study visit (Day 28 or 35). Histological examination of pre- and post-treatment biopsies of the MRG-106-injected lesion from most patients revealed a trend in reduction in neoplastic cell density and depth; 1 patient had a complete loss of the neoplastic infiltrate. Gene expression analysis of the pre- and post-treatment biopsies showed reduction of the PI3K/AKT, JAK/STAT, and NFkB survival pathways and increased cell death consistent with the expected MRG-106 mechanism of action. In the SC cohorts, 3/8 patients had a maximal decrease in their modified Severity-Weighted Assessment Tool (mSWAT) of > 39% indicative of a significant response. One patient at the 900 mg SC dose level had a possible flare of their disease after 3 doses that resolved after 3 weeks. Conclusions: Based on favorable clinical safety, efficacy and PK data, additional patients are being accrued. Updated results will be presented as available. Clinical trial information: NCT02580552.

Evaluation of biosite triage Clostridium difficile panel for rapid detection of Clostridium difficile in stool samples

One hundred two stool samples were tested by both the rapid Triage Clostridium difficile Panel (Triage Panel) and the cytotoxin cell culture assay. Five samples positive by both the C. difficile toxin A (Tox A) and common antigen components of the Triage Panel had cytotoxin titers of > or =10,000. Twenty-three samples were Triage Panel Tox A negative but common antigen positive. Ten of these had cytotoxin titers of 10 to 1,000, but 13 were cytotoxin negative. Bacterial isolates obtained from 8 of these 13 specimens were analyzed for Tox A and B genes by PCR, and only two contained toxigenic bacteria. Thus, the majority of samples positive only for C. difficile common antigen contained nontoxigenic bacteria. A Triage Panel Tox A-positive result indicated a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 33.3, 100, 100, and 88.2%, respectively. A Triage Panel common antigen-positive result indicated a sensitivity, specificity, PPV, and NPV of 100, 82.7, 53.6, and 100%, respectively. The high NPV of the Triage Panel common antigen, together with rapid reporting of results, should prove useful in avoiding unnecessary use of contact precautions and antibiotic treatment for C. difficile-negative patients. However, with Triage Panel common antigen-positive patients, a sensitive cytotoxin assay should be used to distinguish true cytotoxin-positive patients from C. difficile carriers.

Use of plastic vacutainer tubes for quantification of human immunodeficiency virus type 1 in blood specimens

Human immunodeficiency virus type 1 viral load results were compared for paired samples collected in plastic and glass Vacutainer tubes, using both standard (n = 60) and ultrasensitive (n = 66) assays. The results showed a strong correlation (P < 0.0001), and plastic tubes can be substituted for glass tubes.

A multisite trial comparing two cytomegalovirus (CMV) pp65 antigenemia test kits, biotest CMV brite and Bartels/Argene CMV antigenemia

A total of 513 blood specimens, predominantly from organ transplant recipients, human immunodeficiency virus-positive patients, and bone marrow transplant recipients, were tested for cytomegalovirus (CMV) by culture and pp65 antigenemia across four test sites. Peripheral blood leukocytes were examined by using both the Biotest CMV Brite and the Bartels/Argene CMV Antigenemia kits. A total of 109 specimens were positive for CMV, 106 (97%) were positive by antigenemia, and 34 (31%) were positive by culture. According to the manufacturers' instructions, 150,000 cells were applied per slide for the Biotest kit and 200,000 cells per slide for the Bartels kit. A total of 93 specimens (88%) were positive by the Biotest kit, and 86 (81%) were positive by the Bartels kit. In specimens found to be positive by only one kit, the positive cell counts were low (median, 1; range, 1 to 7). When the data from all four sites were combined and analyzed, there was no statistical difference between the performance of the two kits; the Biotest and Bartels kits were found to be equivalent in sensitivity, specificity, and positive and negative predictive values for the detection of CMV pp65 antigenemia.

A standardized plaque reduction assay for determination of drug susceptibilities of cytomegalovirus clinical isolates

Twelve laboratories collaborated in formulating and testing a standardized plaque reduction assay for cytomegalovirus (CMV) cell-associated clinical isolates. Four characterized and plaque-purified CMV strains, as well as six coded clinical isolates obtained after antiviral therapy, were distributed and tested. Good agreement was obtained for four of the clinical isolates, but a broad distribution of results was obtained for two isolates. Analysis of these results indicates the problems associated with clinical isolates, including the large genetic variability and the highly cell-associated phenotype. This collaborative effort, by addressing these problems, represents a significant step toward the development of a standardized assay.

SimulFluor respiratory screen for rapid detection of multiple respiratory viruses in clinical specimens by immunofluorescence staining

A new rapid direct immunofluorescence assay (DFA) respiratory screen reagent for detection of seven common respiratory viruses (respiratory syncytial virus [RSV], influenza A and B viruses, parainfluenza virus types 1 to 3, and adenovirus) was compared with standard single or dual DFA reagents and culture. In total, 1,531 respiratory samples were adequate for testing with both SimulFluor Respiratory Screen (RS) reagent (Chemicon International, Temecula, Calif.) and single or dual DFA reagents. The RS DFA reagent detected 367 (98.4%) and single or dual DFA reagents detected 368 (98.7%) of 373 DFA-positive samples. In addition, the RS DFA reagent was equivalent to or better than culture for detection of all viruses except adenovirus. Only 15 of 799 (1.9%) RS-negative samples inoculated into cell cultures yielded respiratory virus isolates (one RSV, five influenza A virus, two influenza B virus, one parainfluenza virus, and six adenovirus). Sixty-six other virus isolates (13 rhinovirus, 24 cytomegalovirus, 28 herpes simplex virus type 1, and 1 enterovirus) were also recovered in culture. With cytospin preparation of slides, only 7.5% of samples submitted were deemed inadequate for DFA. The availability of a rapid DFA screening reagent for detection of multiple common respiratory viruses within 1 to 2 h of sample collection should be of great benefit in terms of patient management and infection control.

Impact of sample type on rapid detection of influenza virus A by cytospin-enhanced immunofluorescence and membrane enzyme-linked immunosorbent assay

Cytospin-enhanced direct fluorescent-antibody assay (DFA) detected 49 (92.5%) and rapid membrane enzyme-linked immunosorbent assay (ELISA) detected 40 (75.5%) of 53 influenza virus A-positive samples. All 15 positive nasopharyngeal aspirates from children were detected by both tests. In contrast, 34 of 38 (89.5%) positive swabs from adults were detected by DFA, but only 25 (66%) were detected by ELISA.

2-Hour cytomegalovirus pp65 antigenemia assay for rapid quantitation of cytomegalovirus in blood samples

Of 109 blood samples tested for cytomegalovirus (CMV) antigenemia, 18 (16.5%) were positive. CMV Brite detected 13 and CMV Brite Turbo detected 16 of the 18 positives. There was no significant difference in the number of positive cells detected per sample. The seven discrepant samples contained a median of only one positive cell.

Lack of reactivity to CMV pp65 antigenemia testing in a patient with CMV disease following allogeneic bone marrow transplant

Pre-emptive antiviral therapy based on the early detection of CMV infection is an important strategy for the prevention of CMV disease following allogeneic BMT. Accepted methods for early detection of CMV infection include viral culture of blood or bronchial lavage specimens or CMV pp65 antigenemia testing of peripheral blood specimens. We describe a patient with aplastic anemia with worsening liver transaminases after allogeneic bone marrow transplantation who had repeated negative tests for CMV pp65 antigenemia despite positive viral blood cultures. Re-examination of peripheral blood samples with a different pp65 antibody pool revealed the presence of high levels of CMV in peripheral blood leukocytes, confirming a lack of reactivity to the original antibody pool. Following institution of antiviral therapy, a prompt reduction in the number of pp65 antigen-positive peripheral blood leukocytes paralleled a reduction in abnormal transaminases. The practical implications of these findings are discussed.

Papular-purpuric gloves and socks syndrome associated with acute parvovirus B19 infection: case report and review

The papular-purpuric gloves and socks syndrome (PPGSS) was first described in 1990. This syndrome is characterized by fever, acral pruritus, edema, petechiae, and oral erosions. Subsequently, parvovirus B19 has been implicated, in most cases, as the causative agent of this syndrome. To date, with two exceptions, all published cases of PPGSS have been from Europe and the Middle East and have been mainly reported in the dermatology literature. Herein, we report what we believe to be only the second case of documented parvovirus B19-associated PPGSS occurring in the United States. The patient presented with the typical clinical syndrome, and the diagnosis of acute parvovirus B19 infection was documented by serial serologies that demonstrated development of IgM antibody to virus during the acute phase of infection and seroconversion to IgG antibody in the convalescent period. We then review the existing literature on this unusual syndrome and its association with parvovirus B19.

Use of a single swab in multi-microbe or flex trans transport medium for detection of Chlamydia trachomatis by Roche Amplicor PCR and culture in specimens from two different patient populations

The Roche Amplicor PCR increased the detection of Chlamydia trachomatis compared with culture in promptly processed clinical specimens from a local clinic (100 and 86.5%, respectively) and in samples with delayed processing transported from distant facilities (100 and 72.7%, respectively). A single swab collected in culture transport medium was used. Two media, Multi-Microbe and Flex Trans, were tested and found to be equally acceptable.

Comparison of EDTA and acid-citrate-dextrose collection tubes for detection of cytomegalovirus antigenemia and infectivity in leukocytes before and after storage

Duplicate blood samples collected in EDTA and acid-citrate-dextrose (ACD) were compared by cytomegalovirus (CMV) pp65 antigenemia and CMV infectivity on the day of sample collection and after 1 and 2 days of storage at 4 degrees C. No significant difference was detected between EDTA and ACD. However, CMV antigenemia was more sensitive than culture at all time points tested.

Detection of herpes simplex virus in clinical specimens by cytospin-enhanced direct immunofluorescence

For 275 samples tested for herpes simplex virus (HSV), cytospin-enhanced direct immunofluorescence using Chemicon HSV monoclonal antibodies identified 80 (95%) and culture identified 77 (92%) of 84 confirmed positive specimens. Cytospin-prepared slides contained a greater number of total cells than standard cell spots, resulting in fewer inadequate cell smears and a higher HSV detection rate.

Use of a quantitative cytomegalovirus (CMV) antigenemia test in evaluating HIV+ patients with and without CMV disease

Cytomegalovirus (CMV) infection remains a life-threatening infection in patients with HIV disease. A rapid, quantitative diagnostic technique is needed to adi in the diagnosis of CMV disease. This study was undertaken to evaluate the CMV antigenemia test in patients with HIV disease who are at risk for CMV disease. The study included 22 patients who underwent ophthalmologic exams or selected diagnostic techniques in whom CMV cultures and CMV antigenemia tests were performed. All of 11 patients with CMV disease had positive CMV antigenemia assays [range, 48-1,000 positive cells/2 x 10(5) peripheral blood leukocytes (PBL)], and 10 were also CMV viremic. There was no clinical evidence of CMV disease in 11 patients, including seven in whom the CMV antigenemia assay was negative and who remained without evidence of CMV disease after a median follow-up of 159 days. Four patients had low antigenemia levels. Of these four, two subsequently developed CMV retinitis. In conclusion, a positive CMV antigenemia result with > or = 48 positive cells/2 x 10(5) PBL correlated with concurrent CMV disease. The CMV antigenemia test appears to be a valuable tool for the rapid diagnosis of CMV disease in HIV-infected individuals.

Evaluation of CMV Brite kit for detection of cytomegalovirus pp65 antigenemia in peripheral blood leukocytes by immunofluorescence

The CMV Brite antigenemia kit was compared with culture and an established cytomegalovirus pp65 antigenemia assay (CMV AG). Of 300 clinical specimens tested, 92 were positive by CMV Brite, 83 were positive by CMV AG, and 34 were positive by culture. Discrepancies could be attributed to anticytomegalovirus therapy or low-level antigenemia.

Rhinovirus stimulation of interleukin-6 in vivo and in vitro. Evidence for nuclear factor kappa B-dependent transcriptional activation

To further understand the biology of rhinovirus (RV), we determined whether IL-6 was produced during RV infections and characterized the mechanism by which RV stimulates lung cell IL-6 production. In contrast to normals and minimally symptomatic volunteers, IL-6 was detected in the nasal washings from patients who developed colds after RV challenge. RV14 and RV1A, major and minor receptor group RVs, respectively, were potent stimulators of IL-6 protein production in vitro. These effects were associated with significant increases in IL-6 mRNA accumulation and gene transcription. RV was also a potent stimulator of IL-6 promoter-driven luciferase activity. This stimulation was modestly decreased by mutation of the nuclear factor (NF)-IL-6 site and abrogated by mutation of the NF-kappa B site in this promoter. An NF-kappa B-DNA binding activity, mediated by p65, p50, and p52 NF-kappa B moieties, was rapidly induced in RV-infected cells. Activator protein 1-DNA binding was not similarly altered. These studies demonstrate that IL-6 is produced during symptomatic RV infections, that RVs are potent stimulators of IL-6 elaboration, and that RV stimulation IL-6 production is mediated by an NF-kappa B-dependent transcriptional stimulation pathway. IL-6 may play an important role in the pathogenesis of RV infection, and NF-kappa B activation is likely to be an important event in RV-induced pathologies.

Effect of delayed specimen processing on cytomegalovirus antigenemia test results

Blood samples held at either 4 degrees C or room temperature for 1 day had similar mean decreases in number of cytomegalovirus antigenemia-positive cells (52 to 55%) and similar false-negative test results (13 to 14%). After 2 days, samples held at 4 degrees C showed no further decline, whereas samples held at room temperature had a mean 81% decrease in positive cells, a 32% false-negative rate, and a more marked deterioration in cell morphology.

Multiple viral infections in the immunocompromised host: recognition and interpretation

BACKGROUND

During the past decade, diagnostic virology has become an integral part of patient management. Concurrent infection with multiple viruses occurs in both the healthy and immunocompromised host. Many common viruses result in latent infection with the potential for reactivation throughout the life of the host. Superimposed on this are transient infections with yet other viruses.

OBJECTIVES

To review multiple viral infections in immunocompromised hosts, focusing on laboratory recognition and interpretation of results.

STUDY DESIGN

A review of the literature, with case examples from the author's laboratory.

RESULTS

Viral infections are more likely to cause morbidity and mortality in immunodeficient hosts, and early recognition and treatment may be lifesaving. To detect two or more viruses shed concurrently from the same body site requires the use of multiple test modalities, which are now available in many clinical laboratories. Establishing the significance of a virus isolate is a complex process. Knowledge of the specimen source, virus quantitation and characteristics of the patient are helpful. Careful evaluation of the patient's clinical findings together with other laboratory test results, including histopathology, X-rays and the detection of other microorganisms, is also essential.

CONCLUSIONS

The recognition and interpretation of multiple virus infections requires heightened awareness as well as close cooperation and communication between the professionals in the laboratory and physicians at the bedside.

Restriction endonuclease analysis of adenovirus isolates from sporadic and epidemic ocular infections: experience in a clinical laboratory

Adenovirus isolates from 52 patients with ocular infection over a 3-year period were typed by restriction endonuclease analysis in a clinical laboratory. The results indicated that adenovirus type 8 was the most common cause of adenovirus eye infection during this period, being responsible for 42 (81%) of the 52 cases. Of 42 adenovirus type 8 isolates, 22 showed variant patterns by restriction endonuclease analysis and required multiple enzyme digests for identification. These isolates were readily identified by neutralisation tests.

Comparison of quantitative cytomegalovirus antigenemia assay with culture methods and correlation with clinical disease

Blood samples, obtained predominantly from human immunodeficiency virus-infected patients and solid-organ and bone marrow transplant recipients, were submitted to the clinical laboratory for detection of cytomegalovirus (CMV) and were processed by three methods: conventional culture, centrifugation culture, and CMV antigenemia assay with monoclonal antibodies (Clonab CMV; Biotest Diagnostic Corporation, Denville, N.J.) to CMV antigens. Of 496 blood samples tested, 107 were positive by one or more methods: 56 were positive by conventional culture, 27 were positive by centrifugation culture, and 97 were positive for CMV antigen (Ag) by the antigenemia assay. Forty-seven samples were positive by the CMV antigenemia assay only; in these samples, a mean of 12 Ag-positive cells was detected per 200,000 polymorphonuclear leukocytes examined. In contrast, samples positive by the CMV antigenemia assay and both culture methods had a mean of 193 Ag-positive cells, and samples positive by the CMV antigenemia assay and conventional culture alone had a mean of 157 Ag-positive cells. In the antigenemia assay, paraformaldehyde fixation resulted in superior cell morphology when compared with acetone fixation. Use of immunofluorescence staining reduced sample processing time and the complexity of reagent preparation in comparison with immunoperoxidase staining. Differences in the sensitivities between the immunofluorescence and immunoperoxidase staining techniques for detection of antigenemia were minor, with discrepant samples showing only one or two Ag-positive cells. Clinical disease was generally associated with high-level antigenemia, but exceptions were noted. The CMV antigenemia test is a rapid, quantitative assay that greatly facilitated the rapid diagnosis of CMV infection. However, quantitation of antigenemia is labor-intensive, requires processing of samples soon after collection, and does not always correlate with clinical disease in the individual patient.

Comparison of latex agglutination test with enzyme-linked immunosorbent assay for detection of antibody to varicella-zoster virus

A new latex agglutination (LA) test (VZVscan; Becton Dickinson, Cockeysville, Md.) was compared with an enzyme-linked immunosorbent assay (ELISA) (Varicella STAT; Whittaker Bioproducts, Walkersville, Md.) for detection of varicella-zoster virus (VZV) antibody. Of 165 samples tested, 126 (76%) were positive by LA, 123 (73%) were positive by ELISA, and 35 (21%) were negative by both methods. Six samples (4%) were LA positive and ELISA negative or equivocal; three samples (2%) were ELISA positive and LA negative. However, LA failed to detect seroconversions in four adults with varicella in samples obtained 14 to 17 days after the onset of rash. These same samples had ELISA values in the high-positive range. In addition, the recommended LA screening dilution (1:2) is not supported by published data and should be changed.

An adventitious viral contaminant in commercially supplied A549 cells: identification of infectious bovine rhinotracheitis virus and its impact on diagnosis of infection in clinical specimens

The isolation and identification of an adventitious viral agent, infectious bovine rhinotracheitis virus, in one lot of A549 cells from a commercial supplier is described in this report. The presence of infectious bovine rhinotracheitis virus in A549 cells was unexpected and has caused problems in the diagnosis of infections in clinical specimens in three laboratories.

Recurrent genital infection in the guinea pig: differences between herpes simplex types 1 and 2

Recurrence rates of genital infections are significantly higher for herpes simplex virus (HSV) type 2 than HSV type 1. Reasons for this difference are not known. In this report, multiple strains of HSV-1 and HSV-2 were evaluated in the guinea-pig model. HSV-2 strains showed significantly higher genital lesion recurrence than HSV-1, including HSV-1 McKrae strain which is highly recurrent in ocular infections. HSV-2 strains were also associated with more frequent asymptomatic vaginal virus shedding. Further study showed that HSV-1 strains replicated as well as HSV-2 in both the genital tract and the nervous system during acute infection. In addition, no difference was detected between HSV-1 and HSV-2 in nervous system latency. Thus, a number of possible explanations for the observed difference in genital herpes recurrence rates were examined and excluded.

Herpes simplex types 1 and 2: latency in the genital tract of guinea pigs

Guinea pigs were infected with herpes simplex virus (HSV) intravaginally and then sacrificed during latent infection. Virus was recovered from the ganglia, spinal cord and genital tissues by co-cultivation after 1-6 weeks in culture. The virus could not be recovered from the genital tract during the first week of co-cultivation, nor from homogenized genital tissue. Cultivation of genital tissues with acyclovir did not reduce the recovery of HSV. Thus, HSV appeared to establish a truly latent infection in the genital tract and not a persistent infection as previously described.

Advantages of multiple cell culture systems for detection of mixed-virus infections

Simultaneous infections by two or more viruses occur frequently, especially in immunosuppressed patients. In order to detect more than one viral agent in a single specimen, multiple cell systems have been employed in our laboratory. Specimens are routinely inoculated into four different cell cultures, namely: MRC-5, a human diploid lung fibroblast cell strain; A549, a human continuous cell line; primary guinea pig embryo (GPE) cell culture, and primary rhesus monkey kidney (RhMK) cell culture. For rapid detection of cytomegalovirus (CMV) antigen, MRC-5 cells grown in shell vials containing coverslips are also inoculated with the same specimens followed by centrifugation. During 1989, nine cases of multiple-virus isolations were obtained in this laboratory. In all nine patients, CMV was detected in MRC-5 cells. Five of the nine cases were co-infected with HSV-1, three were co-infected with adenovirus, and one was co-infected with both HSV-1 and adenovirus. All four adenovirus isolates were obtained in A549 cells. Of the six HSV-1 isolates, one was detected in all three cell cultures, e.g. MRC-5, A549 and GPE; one was detected in both MRC-5 and A549 cells, and four were isolated in a single-cell type only. For nine CMV-positive cases, five were obtained by both conventional and centrifugation cultures, two each were detected by centrifugation or conventional culture only. Thus for a maximum detection of viruses present in a single specimen, it is suggested that multiple-cell-culture systems, together with more than one technique, should be employed.

Tumor necrosis factor-alpha/cachectin enhances human immunodeficiency virus type 1 replication in primary macrophages

Macrophages are important target cells for human immunodeficiency virus type 1 (HIV-1). The ability of HIV-1 to productively infect macrophages may be influenced by endogenous cytokines that alter the activation state of these cells. In this study, the effect of tumor necrosis factor-alpha/cachectin (TNF alpha), a cytokine with macrophage-activating properties, on HIV-1 replication in primary blood monocyte-derived macrophages was examined. Treatment of macrophages with recombinant human TNF alpha (rTNF alpha), starting before or after HIV-1 infection, consistently enhanced viral production fivefold or greater above control (P less than .01). rTNF alpha was active at low concentrations (0.05-50 ng/ml) and increased the replication of both lymphocyte-tropic (human T lymphotropic virus type IIIB) and macrophage-tropic (human T lymphotropic virus type III BaL) strains of HIV-1. These findings provide additional evidence that TNF alpha may play a role in the pathogenesis of HIV-1 infection by upregulating viral expression in macrophages.

Antiviral activity of 5-iodo-2'-deoxyuridine and related drugs in human keratinocytes infected in vitro with herpes simplex virus type 1

5-Iodo-2'-deoxyuridine (IUDR) is a potent topical antiviral agent in experimental animals but is less active in man for treating cutaneous viral infections. We have shown here that IUDR is 5 times less active in human keratinocytes infected in vitro with herpes simplex virus type 1 than in guinea pig embryo cells infected in culture. To account, in part, for this difference in activity of IUDR, we measured the capacity of these different cultures to catabolize and thus inactivate the drug. IUDR is catabolized by thymidine phosphorylase; activity of this enzyme was very high in human keratinocytes in vitro but was very low in guinea pig embryo cells. The antiviral activity of IUDR in human keratinocytes, however, was not increased by inhibiting thymidine phosphorylase; inhibiting thymidine phosphorylase apparently increased the availability of thymidine that would compete with IUDR and, indeed, the activity of IUDR in infected cells was reduced by addition of thymidine to the medium. These data indicate that the catabolism of IUDR and related analogs alters antiviral activity in human keratinocytes.

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.

Evaluation of immunofluorescent reagents, centrifugation, and conventional cultures for the diagnosis of adenovirus infection

In this study we have evaluated four fluorescent antibody reagents, three monoclonal and one polyclonal, for identification of adenovirus isolates and compared four conventional cultures (human embryonic kidney, A549, HEp-2, and MRC-5 cells) with centrifugation culture for rapid diagnosis. For identification of adenovirus isolates by immunofluorescence, CDC reagent and Adenoclone, both monoclonal antibodies to the hexon group-reactive antigen, were more sensitive and easier to interpret than the other two reagents tested. HEK and A549 cells were the most sensitive for isolation of adenovirus. Although A549 cells were an inexpensive alternative to HEK, A549 cell monolayers deteriorated more rapidly and passages were more often required. Centrifugation cultures with A549 cells detected 77% of positives within 2 days and 100% within 5 days, whereas isolation in conventional culture required up to 10 days for HEK and up to 20 days for MRC-5 cells.

In vitro amplification techniques for the detection of nucleic acids: new tools for the diagnostic laboratory

The acceptance of nucleic acid probes as diagnostic tools for the clinical laboratory has been hampered by a number of factors, including laborious techniques and limited sensitivity. The focus of this review is on the recent development of amplification techniques to enhance the signal generated by nucleic acid-based detection systems. Three general areas are discussed: (1) amplification of target sequences using the polymerase chain reaction or the transcript amplification system, (2) amplification of the probe sequences using Q beta replicase, and (3) amplification of probe-generated signals with compound or "Christmas tree" probes. The hope of these new technologies is to simplify yet improve on the sensitivity of nucleic acid-based tests to enable them to attain a more prominent place in the diagnostic repertoire of the clinical laboratory.

G.D. Edith Hsiung, Ph.D.: virologist and teacher

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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.

Ability of herpes simplex virus (HSV) types 1 and 2 to induce clinical disease and establish latency following previous genital infection with the heterologous HSV type

Guinea pigs were infected intravaginally with either herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2). One month postinoculation, animals were inoculated with the heterologous HSV type and observed for clinical disease and shedding of virus. One month after superinfection, animals were killed, and tissues were cocultivated to detect latent virus. Although the severity of clinical disease and the degree of shedding of virus were greatly reduced by prior infection with the heterologous virus type, superinfection did occur in 82%-90% of animals. Nervous system latency with the superinfecting virus was established in 20% of animals superinfected with HSV-2 and 55% superinfected with HSV-1. Of 21 animals tested, 5 had latent infection with both viruses, 6 with the superinfecting virus only, and 6 with the initial virus only. Protection from nervous system latency with the superinfecting virus correlated best with levels of serum neutralizing HSV antibody before superinfection.

Replication of human adenoviruses in guinea pig embryo cells: an ultrastructural study

Guinea pig embryo (GPE) cells showed different degrees of susceptibility to human adenovirus types as determined by virus infectivity assay and electron microscopic examination. Adenovirus 2 and 5 induced extensive cellular changes and produced high titers of infectious virus in GPE cells as in human cells. Mature progeny virus and protein crystals were observed in both cell types. Adenovirus 7 induced some cellular changes in GPE cells but only a small number of cells yielded progeny virus as determined by electron microscopy. Adenovirus 3, 8 and 31 induced some cellular changes but no progeny virus was found under electron microscopic examination. Characteristic fibers were observed in nuclei of adenovirus 31 infected cells. The ability of human adenovirus 2 and 5 to replicate in GPE cells is an example of an unusual cross-species biological property of certain adenovirus types. This property may be useful as a biological marker for these virus types.

Disseminated adenovirus infection in an immunocompromised host. Pitfalls in diagnosis

In this report, a bone marrow transplant recipient with rapidly fatal gastroenteritis is presented. The presence of intranuclear inclusions on postmortem light microscopic examination of liver, lung, and small bowel tissue was considered diagnostic of cytomegalovirus infection. However, electron microscopic examination of liver tissue demonstrated adenovirus infection. This was confirmed by isolation of an adenovirus type 2 with unusual laboratory features from liver, lung, colon contents, serum, esophageal swab, and oral ulcerations. Results of a complement fixation test for antibodies to adenovirus performed on postmortem serum samples were negative, and a titer of 1:4 was noted for antibody against cytomegalovirus. This case illustrates the diagnostic pitfalls that may be encountered in establishing a specific viral diagnosis in severely ill patients.

Impact of cell culture sensitivity and virus concentration on rapid detection of herpes simplex virus by cytopathic effects and immunoperoxidase staining

Tremendous interest has been generated in the commercial kits now available that incorporate herpes simplex virus isolation in cell culture with immunoperoxidase staining for viral antigen detection. Most studies comparing commercial kits with conventional cell culture techniques have found the kits to be less sensitive. However, different cell cultures were used for the two methods. In this study, mink lung, rabbit kidney, MRC-5, and Vero cells were compared for reisolation of herpes simplex virus from clinical specimens in which viral infectivity titers were concurrently determined. When specimens contained high titers of infectious virus, the cell system used made little difference and all specimens were detected by immunoperoxidase staining at 48 h postinoculation. However, when specimens contained low concentrations of virus, the differences in sensitivity between cell systems became apparent in rapidity of detection and overall isolation rate. Mink lung and rabbit kidney cells were both more sensitive than MRC-5 cells; Vero cells were significantly less sensitive than the other cells tested. The application of immunoperoxidase staining shortened the time to virus detection and lessened, but did not eliminate, the differences between the cell systems. Cytopathic effects alone in the most sensitive cell system equaled or exceeded immunoperoxidase staining applied in less-sensitive cell cultures.

Comparison of fluorescent-antibody-to-membrane-antigen test, indirect immunofluorescence assay, and a commercial enzyme-linked immunosorbent assay for determination of antibody to varicella-zoster virus

The demand for sensitive and specific assays to determine immune status to varicella can be expected to increase with the anticipated availability of a varicella-zoster virus vaccine for use in nonimmune adults, especially health care personnel, and in immunosuppressed children. Although the fluorescent-antibody-to-membrane-antigen (FAMA) test remains the reference standard to which other tests are compared, simpler alternative assays are needed. In this study, the FAMA was compared with a simple indirect immunofluorescence assay (IFA) and a commercially available enzyme-linked immunosorbent assay (ELISA) for the detection of antibody to varicella-zoster virus. One hundred and twelve serum samples were screened by the FAMA test and IFA at a 1:5 dilution, and 100% agreement was found. Of these samples, 101 were available for testing by ELISA, and identical results were obtained with 97 samples (96% agreement). When the samples were screened at a 1:2 dilution, 99 of 101 results agreed. In addition, 31 spinal fluid samples were tested by all three methods. When screening was at a 1:2 dilution, there was 96.8% agreement between the FAMA test and IFA. When the cutoff value established for sera was used for the spinal fluid samples, there was 90.3% agreement between the ELISA and the FAMA test. Thus, both IFA and ELISA can be considered sensitive and specific alternatives to the FAMA test, and in addition, both use commercially available reagents.

Comparison of in situ hybridization and immunologic staining with cytopathology for detection and identification of herpes simplex virus infection in cultured cells

Two recently developed sensitive techniques, in situ hybridization with a biotinylated cloned DNA probe and an avidin-biotin complex immunoperoxidase assay, were compared with the appearance of cytopathic changes for the early detection of herpes simplex virus infection in cell culture. By using commercially made reagents, these detection methods were evaluated in two different cell culture systems inoculated with both high- and low-input multiplicity of virus. The results revealed that both viral antigen and viral DNA detection methods could shorten the time to diagnosis of herpes simplex virus infection in cell culture; however, these methods were most useful in specimens containing low titers of virus when a less sensitive cell system was used. In this study, the avidin-biotin immunoperoxidase method was more sensitive and much cheaper than hybridization with a biotinylated probe. Significantly, when a highly sensitive cell system was used, cytopathic changes alone were comparable in rapidity and sensitivity to viral antigen or DNA detection methods applied in a less sensitive cell system.

Nucleic acid hybridization in the diagnosis of viral infections

Recombinant DNA technology, including molecular cloning and nucleic acid hybridization, is now being applied to problems in clinical virology. Although viral isolation in cell culture remains the most sensitive and specific diagnostic test for many viruses, for some viruses, isolation in cell culture is lengthy or difficult or has not yet been achieved. Utilization of hybridization techniques has already resulted in important new information concerning the pathogenesis of a number of viruses, such as Epstein-Barr virus, hepatitis B virus, and human papillomavirus. In addition, time to diagnosis for viruses such as cytomegalovirus, Epstein-Barr virus, and varicella-zoster virus can be significantly shortened to 36 to 48 hours, a great improvement over standard isolation with obvious importance for patient management. Hybridization techniques have also been applied to screening of antiviral agents. Although results of studies to date have been encouraging, significant problems remain to be solved before these techniques can be applied in a routine diagnostic laboratory. First, more sensitive assays must be developed. One approach is the generation of probes with higher specific activities. Synthesis of single-stranded probes using recombinant M13 bacteriophage as a template results in probes of higher specific activities that also cannot re-anneal to themselves because they are not complementary. Thus, more probe is available to anneal to sample DNA. Synthesis of cRNA probes that form more stable hybrids with DNA is another approach that is receiving attention. A second problem is reagent safety and stability. The most sensitive and commonly used label in the studies reviewed in this article has been 32P. With its half-life of 2 weeks, potential hazards to personnel, and disposal problems, it is probably not suitable for clinical laboratories. A major step in the development of nonradioactive, stable probes has been synthesis of biotinylated nucleotide analogues that can be efficiently incorporated into DNA or RNA. Biotinylated probes are stable for 1 to 2 years at -20 degrees C, and their use obviates the need for autoradiography, thus shortening reaction times. In addition, very high concentrations of probes can be used without the background problems encountered with radiolabels. To date, biotinylated probes have been significantly less sensitive than those labeled with 32P, but continued efforts to improve sensitivity have yielded promising results.(ABSTRACT TRUNCATED AT 400 WORDS)

Genital herpes: pathogenesis and chemotherapy in the guinea pig model

Genital herpes is different from other common venereal diseases in that there is no cure. As yet the natural history of genital herpes is not well understood. There are many unanswered questions regarding the biology of the disease; the virulence of the virus strains, individual host responses, and means for prevention and control all require further investigation. The study of genital herpes has been greatly aided in recent years by the development of animal models. The clinical and pathologic features of acute and recurrent genital disease of guinea pigs inoculated with low doses of herpes simplex virus are similar to those seen in human infection. Therefore, questions not readily studied in human infection--such as latent infection in the nervous system, the natural history, prevention, and treatment of neonatal herpes, the effects of immunosuppression on herpes infection, and the efficacy and toxicity of antiviral drugs and vaccines--are amenable to study in the guinea pig model. The applications of this animal model and its relevance to human disease are herein reviewed.

Herpes simplex encephalitis: analysis of a cluster of cases by restriction endonuclease mapping of virus isolates

In December 1979, there were three deaths from culture-proven herpes encephalitis in 3 weeks in the New Haven area, and a nurse caring for one of these patients developed a herpetic lesion on her nose. The three brain isolates, the isolate from the nurse, and several epidemiologically unrelated strains were analyzed by restriction endonuclease mapping. All were determined to be distinct strains of herpes simplex virus. The possibility that a single strain of virus caused this cluster of cases was therefore examined directly and disproved.