Highly reliable heterologous system for evaluating resistance of clinical herpes simplex virus isolates to nucleoside analogues

Clinical resistance of herpes simplex virus (HSV) types 1 and 2 to acyclovir (ACV) is usually caused by the presence of point mutations within the coding region of the viral thymidine kinase (TK) gene. The distinction between viral TK mutations involved in ACV resistance or part of viral polymorphism can be difficult to evaluate with current methodologies based on transfection and homologous recombination. We have developed and validated a new heterologous system based on the expression of the viral TK gene by the protozoan parasite Leishmania, normally devoid of TK activity. The viral TK genes from 5 ACV-susceptible and 13 ACV-resistant clinical HSV isolates and from the reference strains MS2 (type 2) and KOS (type 1) were transfected as part of an episomal expression vector in Leishmania. The susceptibility of TK-recombinant parasites to ganciclovir (GCV), a closely related nucleoside analogue, was evaluated by a simple measurement of the absorbance of Leishmania cultures grown in the presence of the drug. Expression of the TK gene from ACV-susceptible clinical isolates resulted in Leishmania susceptibility to GCV, whereas expression of a TK gene with frameshift mutations or nucleotide substitutions from ACV-resistant isolates gave rise to parasites with high levels of GCV resistance. The expression of the HSV TK gene in Leishmania provides an easy, reliable, and sensitive assay for evaluating HSV susceptibility to nucleoside analogues and for assessing the role of specific viral TK mutations.

Incorporation and distribution of strontium in bone

The distribution and incorporation of strontium into bone has been examined in rats, monkeys, and humans after oral administration of strontium (either strontium chloride or strontium ranelate). After repeated administration for a sufficient period of time (at least 4 weeks in rats), strontium incorporation into bone reaches a plateau level. This plateau appears to be lower in females than in males due to a difference in the absorption process. Steady-state plasma strontium levels are reached more rapidly than in bones, and within 10 days in the rat. The strontium levels in bone vary according to the anatomical site. However, strontium levels at different skeletal sites are strongly correlated, and the strontium content of the lumbar vertebra may be estimated from iliac crest bone biopsies in monkeys. The strontium levels in bone also vary according to the bone structure and higher amounts of strontium are found in cancellous bone than in cortical bone. Furthermore, at the crystal level, higher concentrations of strontium are observed in newly formed bone than in old bone. After withdrawal of treatment, the bone strontium content rapidly decreases in monkeys. The relatively high clearance rate of strontium from bone can be explained by the mechanisms of its incorporation. Strontium is mainly incorporated by exchange onto the crystal surface. In new bone, only a few strontium atoms may be incorporated into the crystal by ionic substitution of calcium. After treatment withdrawal, strontium exchanged onto the crystal is rapidly eliminated, which leads to a rapid decrease in total bone strontium levels. In summary, incorporation of strontium into bone, mainly by exchange onto the crystal surface, is dependent on the duration of treatment, dose, gender, and skeletal site. Nevertheless, bone strontium content is highly correlated with plasma strontium levels and, in bone, between the different skeletal sites.

Evaluation of a rapid optical immunoassay for influenza viruses (FLU OIA test) in comparison with cell culture and reverse transcription-PCR

The FLU OIA test was evaluated with 146 throat swab specimens from subjects with a flu-like illness in six Canadian clinics during the 1999-2000 flu season. The rate of positivity of the FLU OIA test (41.5%) was significantly lower than that of cell culture (55.2%) or reverse transcription-PCR (55.9%) during a season in which only influenza A virus was detected.

Quantitative analysis of cytomegalovirus (CMV) viremia using the pp65 antigenemia assay and the COBAS AMPLICOR CMV MONITOR PCR test after blood and marrow allogeneic transplantation

The performance of a commercially available qualitative PCR test for plasma (AMPLICOR CMV Test; Roche Diagnostics) and a quantitative PCR test for plasma and leukocytes (COBAS AMPLICOR CMV MONITOR Test; Roche Diagnostics) was evaluated with samples from 50 blood or marrow allogeneic transplant recipients who received short courses of sequential ganciclovir therapy (2 weeks intravenously followed by 2 weeks orally) based on a positive cytomegalovirus (CMV) pp65 antigenemia (AG) assay. The number of persons with a positive CMV test was significantly higher for leukocyte-based assays (AG, 67.5%; PCR, 62.5%) compared to both quantitative and qualitative PCR tests of plasma (42.5 and 35%, respectively). One person developed CMV disease during the study despite a negative AG assay; in this particular case, all PCR assays were found to be positive 10 days before his death. There was a trend for earlier positivity after transplantation and more rapid negativity after initiation of ganciclovir for the tests performed on leukocytes. The mean number of CMV copies as assessed by PCR was significantly higher in leukocytes than in plasma (P = 0.02). Overall, excellent agreement (kappa coefficient, >0.75) was found only between the two PCR assays (qualitative and quantitative) based on plasma. These results suggest that either the pp65 AG assay or the COBAS AMPLICOR CMV MONITOR Test using leukocytes could be used to safely monitor CMV viremia in related allogeneic blood or marrow transplant recipients. Such a strategy will result in preemptive treatment for about two-thirds of the persons with a relatively low rate (<33%) of secondary viremic episodes following short courses of ganciclovir therapy.

Predicting influenza infections during epidemics with use of a clinical case definition

Combined pharyngeal and nasal swab specimens were collected from 100 subjects who presented with a flu-like illness (fever >37.8 degrees C plus 2 of 4 symptoms: cough, myalgia, sore throat, and headache) of <72 hours' duration at 3 different clinics in the province of Quebec, Canada, during the 1998-1999 flu season. The rate of laboratory-confirmed influenza infection was 72% according to cell culture findings and 79% according to the results of multiplex reverse-transcription polymerase chain reaction (RT-PCR) analysis (85%, influenza AH3; 15%, influenza B). All subjects for whom these results were discordant (negative culture and positive PCR) presented with a temperature > or =38.2 degrees C as well as 3 or 4 of the symptoms in the clinical case definition. Stepwise logistic regression showed that cough (odds ratio [OR], 6.7; 95% confidence interval [CI], 1.4-34.1; P=.02) and fever (OR, 3.1; 95% CI, 1.4-8.0; P=.01) were the only factors significantly associated with a positive PCR test for influenza. The positive predictive value, negative predictive value, sensitivity, and the specificity of a case definition including fever (temperature of >38 degrees C) and cough for the diagnosis of influenza infection during this flu season were 86.8%, 39.3%, 77.6%, and 55.0%, respectively.

Evaluation of the human herpesvirus 8 DNA load in blood and Kaposi's sarcoma skin lesions from AIDS patients on highly active antiretroviral therapy

OBJECTIVES

To evaluate the human herpesvirus 8 (HHV-8) DNA load in peripheral blood mononuclear cells (PBMC) and Kaposi's sarcoma (KS) skin lesions of subjects with AIDS and to correlate these measures with the tumour load.

DESIGN

Assessment of the HHV-8 DNA load was performed every 3 months in PBMC and every 6 months in KS skin lesions from seven subjects with AIDS who were receiving highly active antiretroviral therapy (HAART).

METHODS

The HHV-8 DNA load was determined by a quantitative-competitive PCR using 0.2 microg of DNA from PBMC or KS skin biopsies. Staging of KS was performed by evaluating the number and type of cutaneous KS lesions.

RESULTS

The three subjects with the most extensive and active (nodular) KS had the highest amounts of HHV-8 DNA in KS skin lesions and the lowest CD4 T cell counts (< 200 x 10(6)/l). In contrast, the four other subjects with regressing KS while on HAART had a low viral load in their KS lesions. All but one subject who also had multicentric Castleman's disease had low amounts of HHV-8 DNA in PBMC.

CONCLUSION

There is a strong relationship between the tumour burden and the HHV-8 viral load in KS skin lesions of subjects with AIDS, reinforcing the causal link between this herpesvirus and AIDS-related KS.

Recent advances in management of genital herpes

OBJECTIVE

To provide an update on new diagnostic tests and antiviral strategies for managing genital herpes.

QUALITY OF EVIDENCE

Treatment guidelines are based on randomized clinical trials and recommendations from the Expert Working Group on Canadian Guidelines for Sexually Transmitted Diseases. Recommendations concerning other aspects of managing genital herpes (e.g., indications for using type-specific serologic tests) are mainly based on expert opinion.

MAIN MESSAGE

Genital herpes is one of the most common sexually transmitted diseases, affecting about 20% of sexually active people; up to 80% of cases are undiagnosed. Because of frequent atypical presentation and the emotional burden associated with genital herpes, clinical diagnosis should be confirmed by viral culture. Type-specific serologic assays are now available, but their use is often restricted to special situations and requires adequate counseling. New antivirals (valacyclovir and famciclovir) with improved pharmacokinetic profiles have now been approved for episodic treatment of recurrences and suppressive therapy.

CONCLUSION

Wise use of new diagnostic assays for herpes simplex coupled with more convenient treatment regimens should provide better management of patients with genital herpes.

Rapid antiviral effect of inhaled zanamivir in the treatment of naturally occurring influenza in otherwise healthy adults

The antiviral and clinical effects of inhaled zanamivir (10 mg twice daily for 5 days, started within the first or second day of a flulike illness) were evaluated in a randomized, placebo-controlled trial during the 1997-1998 influenza season in Canada. Pharyngeal secretions were collected with swabs every 12 h during 6 days, and symptoms were self-evaluated twice daily during 14 days. After only 12 h of treatment (1 dose), median virus titers decreased by 1.0 log10 TCID50/mL in the zanamivir group (n=17), compared with a 0. 42-log10 increase in the placebo group (n=10; P=.08). This was associated with a 4.5-day (47.4%) reduction in the median time to alleviation of all significant flu symptoms in the zanamivir recipients (P=.03 after adjusting for the initial virus titer and the time between onset of symptoms and treatment). Resistance to zanamivir was not detected in virus isolates by either phenotypic or genotypic assays.

Geographical origin of an introduced pest species, Delia radicum (Diptera: anthomyiidae), determined by RAPD analysis and egg micromorphology

The origin of introduction of the cabbage root fly, Delia radicum Linnaeus to the north-eastern coast of North America in the 19th century has been assumed to be from Europe. From that point of introduction, D. radicum gradually spread westward to occupy available ecological niches. DNA fingerprinting and egg micromorphology were used to determine the most likely geographical origin of the North American populations of this species. Forty-five informative RAPD loci obtained from ten primers and three criteria for egg micromorphology were studied. These characters indicated a common origin for the North American populations and a high similarity between populations from North America and north-western Europe. The results suggest a single entrance point of D. radicum into North America, probably via the north-eastern coast (New York area) from north-western Europe. The implications of this study in assisting selection of natural enemies of this important agricultural pest are discussed.

Human cytomegalovirus glycoprotein B genotypes in blood of AIDS patients: lack of association with either the viral DNA load in leukocytes or presence of retinitis

It has been suggested that human cytomegalovirus (HCMV) glycoprotein B (gB) genotypes could be used as a marker for viral virulence in patients with AIDS. The present study was designed to evaluate a possible association between specific gB genotypes, the presence of HCMV retinitis, and the HCMV viral load. Fifty-four blood samples were obtained from 54 HIV- and HCMV-infected patients. Twenty-seven of these patients were asymptomatic for HCMV, whereas the other 27 patients had been diagnosed recently with HCMV retinitis. HCMV gB genotyping was carried out by using restriction enzyme analysis of PCR-amplified PMNL extracts. Determination of the HCMV viral load in the same specimens was carried out using a quantitative-PCR. HCMV gB genotype 2 was found more frequently than other genotypes in PCR-amplified polymorphonuclear leukocytes (PMNL) of patients with AIDS (P < 0.05) but not more frequently in samples from patients with HCMV retinitis. No significant association was found between any HCMV gB genotypes and the viral load in blood. In conclusion, the actual HCMV gB genotyping system using PMNL provides no additional benefit over the viral load in blood for identification of HIV-infected subjects at risk of HCMV disease.

Characterization of the DNA polymerase and thymidine kinase genesof herpes simplex virus isolates from AIDS patients in whom acyclovirand foscarnet therapy sequentially failed

Herpes simplex virus (HSV) isolates were characterized from 8 AIDS patients in whom acyclovir and foscarnet therapy sequentially failed. The 6 postacyclovir (prefoscarnet) HSV isolates were resistant to acyclovir and susceptible to foscarnet. Of the 9 postfoscarnet isolates, 8 were foscarnet-resistant and acyclovir-susceptible, 1 was resistant to both drugs. Acyclovir- or foscarnet-resistant isolates retained susceptibility to cidofovir. The acyclovir-resistant isolates contained single-base substitutions or frameshift mutations in G or C homopolymer nucleotide repeats of the thymidine kinase gene. In contrast, the foscarnet-resistant strains contained single-base substitutions in conserved (II, III, or VI) or, more rarely, nonconserved (between I and VII) regions of the DNA polymerase (pol) gene. The single isolate exhibiting resistance to acyclovir and foscarnet contained mutations in both genes. In this study of clinical HSV isolates, DNA pol mutations conferring foscarnet resistance were not associated with decreased acyclovir or cidofovir susceptibility.

Expression of the late cytomegalovirus (CMV) pp150 transcript in leukocytes of AIDS patients is associated with a high viral DNA load in leukocytes and presence of CMV DNA in plasma

The expression of a late cytomegalovirus (CMV) transcript (pp150) was sought in peripheral blood leukocytes (PBL) of subjects with AIDS and correlated with the amounts of CMV DNA in PBL and plasma, by means of quantitative polymerase chain reaction (PCR). The detection of the late CMV transcript was associated with a high number of CMV DNA copies in PBL (P=.0015) and with a positive CMV PCR assay in plasma (P<.001). Expression of CMV pp150 mRNA was best predicted by viral DNA thresholds corresponding to 7058 and 30 copies in PBL and plasma, respectively. The detection of CMV pp150 mRNA was associated with the presence of CMV disease in a univariate analysis but not in a multivariate analysis after controlling for the viral DNA load in PBL. Thus, active viral replication as determined by a high CMV DNA load in PBL is reflected by expression of the late CMV transcript in the same cells and by the presence of CMV DNA in plasma.

Human herpesvirus 8 DNA load in leukocytes of human immunodeficiency virus-infected subjects: correlation with the presence of Kaposi's sarcoma and response to anticytomegalovirus therapy

Specific human herpesvirus 8 (HHV-8) DNA sequences were found in leukocytes of 12 of 29 (41.4%) AIDS subjects with Kaposi's sarcoma (KS), whereas they were found in 4 of 43 (9.3%) AIDS subjects without KS (P = 0.003), although the peak HHV-8 DNA load in PCR-positive subjects with KS (mean, 425 copies per 0.2 microgram of DNA) did not significantly differ from the one found in PCR-positive patients without KS (mean, 218 copies). The use of intravenous ganciclovir or foscarnet therapy to treat cytomegalovirus disease did not affect the HHV-8 DNA load in seven patients for whom serial samples were analyzed.

Influence of magnesium substitution on a collagen-apatite biomaterial on the production of a calcifying matrix by human osteoblasts

The induction of a calcifying matrix is of great interest in the restoration of bone defects. In a previous in vitro study we demonstrated that a collagen sponge constituted of type I collagen fibrils, chondroitin sulfates, and hydroxyapatite crystals induces an earlier and a more abundant synthesis of a new extracellular calcifying matrix than do other biomaterials such as collagen or hydroxyapatite alone. Bone mineral contains various amounts of magnesium ions, either adsorbed at the surface of apatite crystals or incorporated inside the crystal structure. Magnesium is known to reduce the degradation rate of tricalcium phosphate ceramics and to influence the crystallization of mineral substance. Thus we evaluated two sponges modified with different substituted apatites. The substituted low magnesium-containing apatite sample decreased the osteoinductive properties of the sponge whereas the substituted high magnesium-containing apatite sample had a toxic effect on bone cells and prevented the formation of any extracellular matrix. Such a toxic effect can be explained by the presence of large numbers of magnesium ions released into the culture medium even though at physiological level magnesium is able to promote bone mineralization and to control the growth of hydroxyapatite crystals. Thus collagen sponges containing hydroxyapatite remain one of the most appropriately evaluated biomaterials used for the restoration of periodontal pockets and bone defects.

Evaluation of the AMPLICOR cytomegalovirus test with specimens from human immunodeficiency virus-infected subjects

The AMPLICOR cytomegalovirus (CMV) test, a new qualitative assay for the detection of CMV DNA in plasma, was compared to conventional methods and quantitative PCR (Q-PCR) assays by using leukocytes and plasma from 179 blood samples from subjects with AIDS. For the diagnosis of CMV disease, cell-based assays such as a Q-PCR with polymorphonuclear leukocytes (Q-PCR-PMNL) and a pp65 antigenemia assay had the highest sensitivities but suffered from a lack of specificity. The best agreement between the results of the Q-PCR-PMNL assay and those of the AMPLICOR test was found when a threshold diagnostic value of 690 copies per 10(5) cells was selected for the Q-PCR-PMNL assay. In that context, the AMPLICOR CMV test had a sensitivity of 96.4% and a specificity of 95.3% when results were compared to results of the cell-based PCR assay. This threshold was close to the one described as associated with the best sensitivity and specificity for the diagnosis of CMV disease in a recently published study (4). Blood samples that tested positive by the Q-PCR-PMNL assay but negative by the AMPLICOR CMV test were associated with viral loads (mean, 785 copies, median, 96 copies per 10(5) leukocytes) lower than the viral loads of blood samples that tested positive by both assays (mean, 21,452 copies; median, 9,784 copies per 10(5) leukocytes) (P = 0.003). The AMPLICOR CMV test gave positive results at least 48 days before the development of symptomatic CMV disease in a longitudinal analysis of a limited subset of patients (n = 6) from whom sequential specimens were available for testing. In conclusion, the AMPLICOR CMV test is a very convenient assay combining rapidity, simplicity, and the possibility of batch testing. A positive result by this test seems particularly important since this implies, in most instances, the presence or the imminence of CMV disease, although a negative test result does not rule out disease.

Phenotypic and genotypic characterization of acyclovir-resistant herpes simplex viruses from immunocompromised patients

Phenotypic and genotypic analyses were done on 30 acyclovir-resistant and 5 acyclovir-susceptible herpes simplex virus (HSV) isolates (22 HSV type 1 and 13 HSV type 2) recovered from 24 subjects. All isolates were susceptible to foscarnet. The phenotypes of the acyclovir-resistant HSV isolates were as follows: 17 were thymidine kinase (TK) deficient, 12 had decreased TK activity (produced low amounts of viral TK) or TK with altered substrate specificity, and 1 was undetermined. Sequencing analysis of the HSV TK gene revealed that 14 (46.7%) of 30 acyclovir-resistant isolates had an insertion or deletion of 1 or 2 nucleotides, especially in homopolymer runs of Gs, Cs, and rarely in As. On the other hand, 16 (53.3%) of 30 acyclovir-resistant isolates had point mutations in conserved or nonconserved regions of the TK gene. In conclusion, HSV can develop multiple strategies to exhibit acyclovir resistance, including, in about half of the cases, frameshift mutations in homopolymer nucleotide stretches of the TK gene.

Quantitation of cytomegalovirus: methodologic aspects and clinical applications

Cytomegalovirus (CMV) is an important pathogen in transplant recipients and human immunodeficiency virus (HIV)-infected individuals. Major progress has been made in developing quantitative detection methods for CMV in recent years. Due to their high sensitivity, these assays can detect CMV early, and quantitation may be useful in predicting the patient's risk for disease and in monitoring the effect of antiviral therapy. This review discusses methodological aspects of currently used quantitative assays for CMV (i.e., viral culture techniques, antigen detection assays, DNA detection assays including PCR, branched-DNA assay, and the DNA hybrid capture assay) and addresses the correlation of systemic and site-specific CMV load and CMV disease in different populations of immunosuppressed patients as well as the response to antiviral treatment. To date, direct antigen detection and molecular techniques have largely replaced traditional culture-based techniques for CMV quantitation. In general, a high systemic CMV load is correlated with CMV disease. This correlation is strong in the HIV-infected population and in solid-organ transplant recipients but less clear in allogeneic marrow transplant recipients. Measuring the viral load at specific anatomic sites may be an alternative way to assess disease activity in situations where the systemic viral load correlates poorly with disease activity. A reduction of the systemic CMV load also correlates with a response to antiviral treatment, but more research is needed to evaluate the role of viral load as a surrogate marker for drug resistance. Due to the widespread use of quantitative CMV detection techniques to direct and monitor antiviral treatment, there is a great need for an assessment of the reproducibility of test results and better standardization of the assays.

Comparative evaluation of the cytomegalovirus DNA load in polymorphonuclear leukocytes and plasma of human immunodeficiency virus-infected subjects

The cytomegalovirus (CMV) DNA load was determined in polymorphonuclear leukocytes (PMNL) and plasma samples from 106 human immunodeficiency virus-infected subjects at risk of developing CMV disease (group 1) and from 27 AIDS patients with documented CMV disease (group 2). For both groups, the number of CMV copies in PMNL was significantly higher than in plasma when results were derived from an equivalent blood volume (P < .001, PMNL vs. plasma). Additionally, group 2 (symptomatic) patients had a greater viral DNA load than group 1 (asymptomatic) subjects (P < .001 for both PMNL and plasma). The sensitivity, specificity, and positive and negative predictive values of qualitative polymerase chain reaction using PMNL (PCR-PMNL) for the presence of CMV disease were 100%, 58%, 38%, and 100%, respectively, compared with 70%, 93%, 74%, and 92% for qualitative PCR-plasma and 93%, 92%, 76%, and 98% for quantitative PCR-PMNL using a cutoff of 16,000 copies/mL. Thus, the best strategy for diagnosing CMV disease in these individuals relies on quantitative assessment of the viral DNA load in PMNL.

Emergence and prevalence of cytomegalovirus UL97 mutations associated with ganciclovir resistance in AIDS patients

OBJECTIVES

To evaluate the prevalence of the most common cytomegalovirus (CMV) UL97 mutations associated with ganciclovir resistance directly in polymorphonuclear leukocytes (PMNL) of patients with AIDS and CMV retinitis. Also to correlate the presence (or absence) of these mutations with the systemic CMV viral load and the ophthalmologic outcome of these subjects.

METHODS

Monthly blood samples were obtained from 19 patients with AIDS and CMV retinitis who had been treated with systemic ganciclovir for > or = 2 months. Detection of CMV UL97 mutations was done using nested PCR amplification followed by restriction enzyme analysis. The viral load was assessed with a polymerase chain reaction-based assay and non-isotopic hybridization detection.

RESULTS

CMV UL97 mutations were detected in PMNL of four of 13 (30.8%) patients who had been treated with ganciclovir for > or = 3 months but in none of six patients who had been treated for < 3 months. All four patients with detectable UL97 mutations were presenting evidence of retinitis progression at the time those mutations were first detected (mean, 145.7 days of ganciclovir) and three of four patients had a viral DNA load > 10000 copies per 10(5) PMNL contrasting with the copy numbers in the 15 subjects without mutations (mean, 492.9 copies per 10(5) PMNL after a mean of 146.8 days of ganciclovir).

CONCLUSIONS

The prevalence of the most common CMV UL97 mutations associated with ganciclovir resistance in PMNL of patients with AIDS treated for > or = 3 months (30.8%) appears to be higher than the rate of emergence of ganciclovir-resistant CMV isolates as previously reported using phenotypic assays (about 8%). Moreover, the detection of these mutations is associated with a considerable increase in the CMV DNA load in the blood as well as with progression of CMV retinitis during ganciclovir therapy.

Molecular and physiological effects of alpha-tropomyosin ablation in the mouse

Tropomyosin (TM) is an integral component of the thin filament in muscle fibers and is involved in regulating actin-myosin interactions. TM is encoded by a family of four alternatively spliced genes that display highly conserved nucleotide and amino acid sequences. To assess the functional and developmental significance of alpha-TM, the murine alpha-TM gene was disrupted by homologous recombination. Homozygous alpha-TM null mice are embryonic lethal, dying between 8 and 11.5 days post coitum. Mice that are heterozygous for alpha-TM are viable and reproduce normally. Heterozygous knockout mouse hearts show a 50% reduction in cardiac muscle alpha-TM mRNA, with no compensatory increase in transcript levels by striated muscle beta-TM or TM-30 isoforms. Surprisingly, this reduction in alpha-TM mRNA levels in heterozygous mice is not reflected at the protein level, where normal amounts of striated muscle alpha-TM protein are produced and integrated in the myofibril. Quantification of alpha-TM mRNA bound in polysomal fractions reveals that both wild-type and heterozygous knockout animals have similar levels. These data suggest that a change in steady-state level of alpha-TM mRNA does not affect the relative amount of mRNA translated and amount of protein synthesized. Physiological analyses of myocardial and myofilament function show no differences between heterozygous alpha-TM mice and control mice. The present study suggests that translational regulation plays a major role in the control of TM expression.

A case of ganciclovir-resistant cytomegalovirus (CMV) retinitis in a patient with AIDS: longitudinal molecular analysis of the CMV viral load and viral mutations in blood compartments

OBJECTIVE

To study the temporal relationships between cytomegalovirus (CMV) viral load and specific UL97 mutations in polymorphonuclear leukocytes (PMNL) and plasma samples from a patient with AIDS who developed ganciclovir-resistant CMV retinitis.

METHODS

Sequential PMNL and plasma samples were analysed for determination of the CMV viral load using non-molecular methods and a quantitative polymerase chain reaction (PCR) assay. Screening of the same samples for the most common mutations conferring ganciclovir resistance was performed using nested PCR and restriction enzyme analysis.

RESULTS

At the time of progression of CMV retinitis (after 6 months of ganciclovir), a rapid increase in the CMV DNA load was found in both PMNL and plasma samples. This increase paralleled the emergence of a specific mutation (V594) in the same samples and recovery of ganciclovir-resistant blood isolates. In this patient, however, the only tests that substantially predicted the progression of CMV disease were the quantitative PCR assay using PMNL and to a lesser extent the pp65 antigenemia assay.

CONCLUSIONS

Quantitative evaluation of the CMV viral load in PMNL using sensitive assays such as PCR appears to be a promising approach for monitoring antiviral therapy in subjects with AIDS. In addition, common mutations conferring ganciclovir resistance can be detected directly in PMNL and plasma samples.

Antiviral susceptibilities and analysis of UL97 and DNA polymerase sequences of clinical cytomegalovirus isolates from immunocompromised patients

Antiviral susceptibilities to ganciclovir, foscarnet, and cidofovir and sequencing of UL97 and DNA polymerase were done on 23 cytomegalovirus (CMV) isolates from 10 immunocompromised persons with end-organ CMV disease who were treated with ganciclovir alone or ganciclovir followed by foscarnet. Screening of UL97 for ganciclovir resistance mutations was done by restriction digest analysis. Of 14 isolates resistant to ganciclovir, 11 (79%) contained one or more UL97 mutations at codons known to confer resistance to this compound, and 10 (91%) had a concordant mutant pattern by restriction digest analysis. Of 9 isolates containing mutations in conserved regions of the DNA polymerase, 8 were resistant to ganciclovir, and 4 were cross-resistant to cidofovir. All isolates were susceptible to foscarnet. It is concluded that ganciclovir-resistant clinical CMV isolates may contain UL97 mutations, DNA polymerase mutations, or mutations in both genes. Ganciclovir therapy may select for CMV isolates that are cross-resistant to cidofovir.

The fine structure of the egg shells of the cabbage maggot,Delia radicumL. (Diptera: Anthomyiidae), and its relation with developmental conditions and oviposition site

The fine structure and evolution of the egg shells of the cabbage maggot, Delia radicum, were studied in a French strain. The chorion did not undergo any modification at oviposition and consisted of three layers, except for the longitudinal strip, where the outer layer was lacking. The vitelline membrane of the oocyte was transformed by densification after oviposition. Differences in the longitudinal strip of the chorion were found between three strains of D. radicum. The strip was 650 μm long in the French strain and a Canadian strain, but only 250 μm long in a Moroccan strain. We also studied the effect of relative humidity on the hatching rate of eggs of the French strain and found that low relative humidity decreased the hatching rate. Finally, the function of the longitudinal strip was discussed in relation to climatic conditions.

Early effects of ganciclovir therapy on the quantity of cytomegalovirus DNA in leukocytes of immunocompromised patients

The cytomegalovirus (CMV) DNA load in leukocytes was measured in 26 immunocompromised patients with CMV disease before and after 10 days of intravenous ganciclovir therapy. Before therapy, the circulating DNA burden of bone marrow transplant recipients was significantly lower than that of other transplant or AIDS patients. Ganciclovir induction therapy significantly decreased the viral DNA load in the leukocyte populations of most patients.

Quantitation of cytomegalovirus (CMV) DNA in leukocytes of human immunodeficiency virus-infected subjects with and without CMV disease by using PCR and the SHARP Signal Detection System

We report the development of a simple and rapid PCR assay for quantitation of the cytomegalovirus (CMV) DNA load in polymorphonuclear leukocytes. Using this system, a very good correlation was found between a high number of CMV copies in the blood and the presence of CMV disease in subjects with AIDS.

Effect of foscarnet on quantities of cytomegalovirus and human immunodeficiency virus in blood of persons with AIDS

Four intravenous dosages of foscarnet given for 10 days were compared with no therapy in persons with AIDS who had asymptomatic cytomegalovirus (CMV) viremia. CMV viremia was quantitated by endpoint cell dilution microcultures, pp65 antigenemia assay, and measurement of CMV DNA in peripheral blood leukocytes by a quantitative-competitive PCR. Human immunodeficiency virus type 1 (HIV-1) viremia was quantitated by endpoint cell dilution microculture, serum p24 antigen assay, and PCR for HIV-1 RNA in plasma. Twenty-seven subjects who had received a median of 22 months of nucleoside antiretroviral therapy were enrolled. Twenty-two subjects received foscarnet, which was well tolerated and decreased the CMV burden, as reflected by all three indicator assays. During the 10 days of dosing, the level of CMV viremia, as measured by 50 percent tissue culture infective doses, decreased from 117.5 to 12.7 (P = 0.001), the amount of CMV DNA decreased from 20,328 copies to 622 copies per 150,000 leukocytes (P = 0.02), and the level of CMV pp65 antigenemia decreased from 14.9 to 1.6 positive peripheral blood mononuclear cells per 50,000 leukocytes (P = 0.008). A significant pharmacodynamic relationship was found between the peak foscarnet concentration and a decrease in the level of CMV antigenemia (P < 0.05). Foscarnet had no effect on quantitative HIV-1 microcultures during the 10 days of treatment, but the HIV-1 p24 antigen level in serum decreased significantly, from 454 to 305 pg/ml (P = 0.01). Also, a significant pharmacodynamic relationship was seen between plasma HIV-1 RNA concentrations and both peak foscarnet concentration (P < 0.01) and the area under the foscarnet time-concentration curve (P < 0.05). Reductions in the levels of CMV and HIV-1 viremia correlated quantitatively with systemic exposure to foscarnet, whereas control subjects actually experienced an increase in CMV and HIV-1 burdens. The dual antiviral activity of foscarnet shown in this trial encourages investigation of its use in combination with other antiretroviral therapies for persons with AIDS.

Chemical and X-ray analysis of fluoride, phosphorus, and calcium in human foetal blood and hard tissues

To evaluate the beneficial effect of prenatal fluoride supplementation, the presence of fluoride in hard tissues in two populations of human foetuses coming from fluoridated (> or = 0.7 parts/10(6) F in drinking water) and non-fluoridated areas (< or = 0.1 parts/10(6) F in drinking water) were compared by chemical analysis and X-ray microanalysis. The fluoride concentrations measured in maternal and venous cord blood confirmed that placental transfer of fluoride was passive when fluoride intake was low. Total fluoride contents of tooth germs and mandibular bone appeared to increase with fluoride level in drinking water. However, these concentrations were too low to be detected by X-ray microanalysis. Phosphorus and calcium total contents were identical in mandibular and femoral bone of both populations. In incisor germs, phosphorus and calcium concentrations in enamel and dentine close to the amelodentinal junction did not differ significantly between the two populations. It is suggested that the low fluoride concentrations in enamel and dentine formed in utero would not have a significant effect on acid solubility.

Ablation of the murine alpha myosin heavy chain gene leads to dosage effects and functional deficits in the heart

The alpha-myosin heavy chain (alpha-MyHC) is the major contractile protein expressed in the myocardium of adult mice. We have produced mice carrying a null mutation of alpha-MyHC by homologous recombination in murine ES cells. Homozygous null animals die between 11 and 12 d in utero of gross heart defects, while alpha-MyHC+/- heterozygotes survive and appear externally normal. The presence of a single functional alpha-MyHC+ allele in heterozygous animals results in reduced levels of the transcript and protein as well as fibrosis and alterations in sarcomeric structure. Examination of heart function using a working heart preparation revealed severe impairment of both contractility and relaxation in a subset of the alpha-MyHC+/- animals. Thus, two alpha-MyHC+ alleles are necessary for normal cardiac development, and hemizygosity for the normal allele can result in altered cardiac function.

HPRT-APRT-deficient mice are not a model for lesch-nyhan syndrome

Complete hypoxanthine-guanine phosphoribosyl-transferase (HPRT) deficiency in humans results in the Lesch-Nyhan syndrome which is characterized, among other features, by compulsive self-injurious behavior. HPRT-deficient mice generated using mouse embryonic stem cells exhibit none of the behavioral symptoms associated with the Lesch-Nyhan syndrome. Administration of drugs that inhibit adenine phosphoribosyltransferase (APRT) in HPRT-deficient mice has produced the suggestion that deficiency of APRT in combination with HPRT-deficiency in mice may lead to self-mutilation behavior [C.L. Wu and D.W. Melton (1993) Nature Genet. 3, 235-240]. To test this proposition, we bred HPRT-APRT-deficient mice. Although the doubly-deficient mice excrete adenine and its highly insoluble derivative, 2,8-dihydroxyadenine, which are also associated with human APRT deficiency, additional abnormalities or any self-injurious behavior were not detected. Thus, APRT-HPRT-deficient mice, which are devoid of any purine salvage pathways, show no novel phenotype and are not a model for the behavioral abnormalities associated with the Lesch-Nyhan syndrome as previously suggested.

Strontium distribution and interactions with bone mineral in monkey iliac bone after strontium salt (S 12911) administration

The analysis of the interaction of strontium (Sr) with bone mineral is of interest because a new agent containing Sr (S 12911) has shown positive effects on bone mass in various animal models of osteoporosis and is currently being developed for preventive and curative treatment of postmenopausal osteoporosis. Iliac bone samples were obtained from 20 male monkeys: 4 untreated control animals, 12 animals sacrificed at the end of a 13-week treatment with high dose levels of S 12911 (750, 275, or 100 mg/kg/day orally), and 4 animals sacrificed 6 weeks after the end of a 13-week treatment with S 12911 (750 or 100 mg/kg/day orally). The distribution of Sr was determined and quantified by X-ray microanalysis. Changes at the crystal level were evaluated by X-ray diffraction and Raman microspectrometry. In the control animals, traces of Sr were found to be homogeneously distributed throughout the bone tissue. In the treated monkeys, Sr could only be detected in calcified matrix. In monkeys sacrificed at the end of the treatment, Sr was found to be dose-dependently incorporated into the mineral substance of the compact and cancellous bone. Sr was heterogeneously distributed with three to four times more Sr in new than in old compact bone, and approximately two and a half times more Sr in new than in old cancellous bone. The bone Sr content dramatically decreased in the animals sacrificed 6 weeks after the end of the treatment. Diffraction showed no significant changes in the characteristics of the crystal lattice. Sr appeared to be easily exchangeable from bone mineral and was slightly linked to mature crystals through ionic substitutions. Even at the highest dose level tested, less than 1 calcium ion out of 10 was substituted by 1 Sr ion in each crystal. In conclusion, taken up by bone, Sr was heterogeneously distributed with a higher concentration in new than in old bone but induced no major modifications of the bone mineral (crystallinity, crystal structure) at the crystal level. As a result, a treatment with S 12911 Sr salt should not induce any alteration of bone mineral.

Quantitation of cytomegalovirus DNA and characterization of viral gene expression in bronchoalveolar cells of infected patients with and without pneumonitis

Cytomegalovirus (CMV) is often present in bronchoalveolar lavage (BAL) fluid of immunosuppressed patients without CMV pneumonitis. The amount of viral DNA within BAL cells of patients with definite CMV pneumonitis and of viral shedders was quantitated by polymerase chain reaction (PCR) and the extent of CMV gene expression within BAL cells was defined by reverse transcription - PCR. No viral DNA was detected in 6 viral shedders, and 12 had low copy numbers (mean, 72 copies/10(5) BAL cells; median, 20) compared with numbers in pneumonitis patients (267,580 and 57,000, respectively). When CMV intranuclear inclusions were absent within BAL cells of patients with pneumonitis, copy numbers (mean, 9362; median, 7110) were still significantly higher than among shedders. Expression of viral glycoprotein H mRNA was detected in BAL cells of all 11 pneumonitis patients tested but in 0 of 18 viral shedders. Thus, high-grade infection and viral replication within BAL cells are integral features of CMV pneumonitis but not viral shedding.

Adenine phosphoribosyltransferase-deficient mice develop 2,8-dihydroxyadenine nephrolithiasis

Adenine phosphoribosyltransferase (APRT) deficiency in humans is an autosomal recessive syndrome characterized by the urinary excretion of adenine and the highly insoluble compound 2,8-dihydroxyadenine (DHA) that can produce kidney stones or renal failure. Targeted homologous recombination in embryonic stem cells was used to produce mice that lack APRT. Mice homozygous for a null Aprt allele excrete adenine and DHA crystals in the urine. Renal histopathology showed extensive tubular dilation, inflammation, necrosis, and fibrosis that varied in severity between different mouse backgrounds. Thus, biochemical and histological changes in these mice mimic the human disease and provide a suitable model of human hereditary nephrolithiasis.

Detection of ganciclovir resistance mutations quantitation of cytomegalovirus (CMV) DNA in leukocytes of patients with fatal disseminated CMV disease

Cytomegalovirus (CMV) UL97 mutations associated with ganciclovir resistance at codons 460, 594, and 595 were detected by polymerase chain reaction (PCR) followed by restriction enzyme analysis in CMV blood isolates and directly in polymorphonuclear leukocyte (PMNL) DNA extracts of 4 subjects who died of progressive disseminated CMV disease due to ganciclovir-resistant CMV strains. The CMV DNA load was also serially determined in leukocyte fractions of these patients using a quantitative-competitive PCR assay. There was excellent concordance between specific UL97 mutations in blood culture isolates and those detected in PMNL fractions for all patients. Emergence of such UL97 mutations during ganciclovir therapy was associated with an increasing CMV DNA burden in leukocytes of the 2 patients with AIDS but not in the 2 subjects with chronic lymphocytic leukemia. Rapid molecular strategies, including detection of common CMV UL97 mutations and CMV DNA quantitation, can be used directly in leukocytes of immunocompromised subjects with CMV disease to monitor antiviral therapy.

APRT: a versatile in vivo resident reporter of local mutation and loss of heterozygosity

We describe an in vivo mutagenesis model that utilizes reverse mutation and forward mutation at the endogenous Aprt locus. Reverse mutation provides an in situ method for detecting environments or agents that cause point mutations. Forward mutation detects large chromosomal events, including mitotic recombination, chromosome loss, and large multilocus deletion, all of which can lead to loss of heterozygosity. Detection of reverse mutation in vivo is based on the differential capacity of Aprt and Aprt cells to sequester radiolabeled adenine by catalyzing its conversion to adenosine monophosphate with subsequent incorporation into nucleic acids. Cells lacking APRT activity cannot accumulate exogenously administered, tagged adenine, whereas Aprt+ cells can and will thereby become marked. Thus, genetically modified mice with mutant but revertible Aprt alleles should be a useful vehicle for in situ detection of mutagenic activity in the whole animal. the feasibility of this model has been illustrated, first, by showing that APRT-deficient mice are viable and, second, by demonstrating that the minority of Aprt+ cells within a chimeric tumor growing in an Aprt+ mouse can be selectively labeled following IP injection of [14C]-adenine and can be identified by autoradiography. Forward mutation, detected by growth in selective medium of primary cells derived from Aprt+/- heterozygous mice, provides on independent estimate of in vivo mutation frequency. The frequency with which Aprt colonies arise provides a measure of the frequency of Aprt(-)-negative cells in the tissue at that point in time. Culture of skin fibroblasts in 2,6-diaminopurine (DAP) produced Aprt+ colonies with a frequency of about 10(-4). This frequency is similar to that found for human T lymphocytes from individuals heterozygous at the Aprt locus. In both cases, the majority of mutagenic events involved allele loss. Polymerase chain reaction with linked polymorphic microsatellites on mouse chromosome 8 demonstrated that allele loss was mediated mostly by mitotic recombination, as was the case for human T lymphocytes. The high frequency of mitotic recombination and allele loss at a neutral locus has significant implications for the process of tumorigenesis and argues that spontaneous or induced mitotic recombination may play a causal role in the progression to cancer.

Distribution of thrombospondin and integrin alpha V in DCIS, invasive ductal and lobular human breast carcinomas. Analysis by electron microscopy

The ultrastructural distribution of thrombospondin (TSP) and its cell surface receptor, integrin alpha V, was studied in two cases of human breast carcinoma: one of ductal carcinoma in situ (DCIS) with an invasive component, and one of invasive lobular carcinoma. In DCIS, moderate immunolabelling for TSP and integrin alpha V was observed in the rough endoplasmic reticulum and at the plasma membrane of intraductal carcinoma cells. TSP was also associated with extracellular matrix collagen fibrils surrounding in situ carcinoma cells. In the invasive part of this ductal carcinoma, most of the malignant cells were negative for TSP, while integrin alpha V was moderately expressed in these cells. In sharp contrast, typical strands of invasive lobular carcinoma cells in "Indian file" showed moderate TSP immunostaining in the rough endoplasmic reticulum and strong immunoreactivity for TSP at the plasma membrane and in the extracellular matrix. Moderate to strong immunoreactivity for integrin alpha V was also observed in invasive lobular carcinoma cells. Because of the role of TSP during cancer cell invasion, the different expression patterns of TSP in invasive ductal versus lobular carcinoma may well reflect biological differences between these two types of breast carcinoma and could account for the peculiar diffuse invasive behaviour of breast lobular carcinoma cells.

Functional morphology of the mymariform and sacciform larvae of the egg parasitoid Anaphes victus Huber (Hymenoptera: Mymaridae)

The mymariform and sacciform larvae of Anaphes victus Huber (Hymenoptera: Mymaridae), an egg parasitoid of Curculionidae, are apneustic and segmented. We found a perioral cordiform structure around the buccal cavity of the mymariform larva that may have a role in the ingestion of host contents or in fights with conspecific larvae in situations of superparasitism. We observed fights between mymariform larvae, which regulate superparasitism in this strictly solitary species, in which sensorial structures of two distinct types found on the thoracic setae could have played a role. The adaptive value of these larval fights is discussed.

Quantitation of human cytomegalovirus glycoprotein H gene in cells using competitive PCR and a rapid fluorescence-based detection system

A technique is described for quantitation of the human cytomegalovirus (HCMV) glycoprotein H (gH) gene in cells using a quantitative-competitive polymerase chain reaction (QC-PCR). Two recombinant DNA molecules, differing in size due to a 92-bp deletion within the HCMV gH sequence, were used in co-amplification studies to construct a standard curve from which the copy number of the gH gene present in clinical samples could be interpolated. The use of primers labeled with a fluorescent dye allowed direct detection of the amplified products by measuring the amount of fluorescence emitted by each specific PCR fragment with an automated DNA sequencer coupled to a software program. This system was validated subsequently using bronchoalveolar lavage cells obtained from immunocompromised patients and found to be highly sensitive and reproducible over a range of 5-50,000 HCMV gH copies. This rapid procedure could easily be applied to study the pathogenesis of HCMV infection, identify the patients at high risk of developing HCMV disease, and monitor the effects of antiviral therapy at the molecular level.

Phenotypic and genotypic characterization of acyclovir-resistant varicella-zoster viruses isolated from persons with AIDS

Phenotypic and genotypic analyses were done on 17 varicella-zoster virus (VZV) isolates recovered from 10 persons with AIDS (mean CD4 cell count, 16.4/mm3) who had chronic VZV lesions. Eleven acyclovir-resistant isolates were recovered from 10 patients after a mean of 20.1 weeks of therapy. Six susceptible isolates were recovered before acyclovir treatment (n = 1), early during therapy (n = 4; mean time, 4.2 weeks), or after discontinuation of acyclovir (n = 1). Acyclovir-resistant VZV isolates were deficient in thymidine kinase (TK) or induced a TK with altered substrate specificity; all isolates were susceptible to foscarnet. Ten of 11 acyclovir-resistant mutants contained tk gene mutations, including single nucleotide substitutions in highly conserved binding sites (n = 2) as well as nucleotide deletions (n = 4) and insertions (n = 4). These findings suggest that multiple, nonuniform mutations within the tk gene are associated with acyclovir-resistant VZV phenotypes.

[Harvesting thin and semi-thin skin from the scalp: risks and their prevention]

The complications of raising scalp grafts are dominated by the risks of haemorrhage and alopecia, which can be prevented by careful preparation of the donor site, perfect intraoperative coordination and close surveillance of epithelialisation. The authors report their experience in the Freyming-Merlebach burns unit, with particular emphasis on the value of this technique in children.