W. Lawrence Drew

OUTBREAK OF BURKITT'S-LIKE LYMPHOMA IN HOMOSEXUAL MEN

Four cases of Burkitts-like lymphoma (undifferentiated, monoclonal, B-cell tumours) in homosexual men were seen in a 9-month period in San Francisco. One tumour contained both Epstein-Barr-virus nuclear antigen (EBNA) and cytomegalovirus (CMV) antigen. Another tumour contained EBNA, and a third contained no viral antigen, but EBNA and CMV antigens were detected in the overlying epithelium. This outbreak widens the array of neoplasms affecting immunosuppressed homosexual men and provides further evidence of an oncogenic role for EBV and CMV.

CYTOMEGALOVIRUS AND KAPOSI'S SARCOMA IN YOUNG HOMOSEXUAL MEN

10 homosexual men with Kaposis sarcoma (KS) were studied for evidence of cytomegalovirus (CMV) infection. IgG and IgM antibodies to CMV were detected in 9 out of 9 and in 7 out of 9 of these patients, respectively. CMV was recovered from body secretions or peripheral blood of 7 patients. Viral cultures of KS tumour biopsy specimens were negative in 8 out of 8 patients, but CMV RNA was detected by in-situ hybridisation in 2 out of 3 and CMV antigen(s) by immunofluorescence in 6 out of 9. Normal tissue specimens from 3 KS patients were negative for CMV antigen. These observations suggest an association of CMV with KS.

Viral DNA Polymerase Mutations Associated with Drug Resistance in Human Cytomegalovirus

Certain mutations in the viral DNA polymerase (pol) gene are known to confer drug resistance when transferred to susceptible human cytomegalovirus (CMV) strains, whereas other putative resistance mutations remain unproven. A new marker-transfer technique was used to produce recombinant CMV strains, to determine the drug susceptibility phenotypes conferred by 10 pol mutations (9 observed in clinical isolates). Various degrees of resistance to ganciclovir and cidofovir were conferred by mutations D301N, N410K, D413E, T503I, and L516R, which are located within exonuclease functional domains where D301N and D413E affect highly conserved residues. Mutations A692S, E756K, and E756D, which are not located within recognized functional domains, each conferred foscarnet resistance. This study significantly increases the number of confirmed CMV pol resistance mutations, at both conserved and nonconserved loci, with implications for molecular mechanisms and the genotypic diagnosis of antiviral resistance.

Cytomegalovirus UL97 Phosphotransferase Mutations That Affect Susceptibility to Ganciclovir

Most ganciclovir (GCV)-resistant cytomegalovirus (CMV) isolates contain UL97 gene mutations at codon 460 or 520 or between codons 590 and 607, where an increasing variety of mutations have been detected, including deletions. To determine their phenotypic effect, 9 UL97 mutations not previously studied were transferred to drug-sensitive laboratory CMV strains that contained unique restriction sites developed for this purpose. Deletion of the entire codon range 591-607 conferred a 6-fold increase in GCV resistance, with little effect on viral replication. Some mutations found in clinical isolates, including C592G and A594T, conferred only 2-3-fold decreases in GCV susceptibility. For C592G, this phenotype was confirmed by transfer to different CMV strains and by restoration of full drug susceptibility after removal of the mutation. Low drug levels resulting from oral GCV therapy may predispose the virus to the initial selection of these low-grade UL97 resistance mutations and to later accumulation of other mutations and greater resistance.

Evolution of Mutations Conferring Multidrug Resistance during Prophylaxis and Therapy for Cytomegalovirus Disease

In a human immunodeficiency virus-infected subject, cytomegalovirus (CMV) isolated 9 months after the patient began oral ganciclovir prophylaxis was resistant to ganciclovir and cidofovir and contained mutations in both UL97 and Pol coding regions. At 1 year, retinitis developed, which progressed despite intravenous ganciclovir followed by foscarnet and then cidofovir. A subsequent buffy coat virus isolate was resistant to all three drugs and contained new mutations in UL97 and Pol. By individually transferring the observed mutations to laboratory strain AD169, it was shown that a mutation at codon 603 of UL97 conferred resistance to ganciclovir, a mutation at codon 412 of Pol conferred resistance to both ganciclovir and cidofovir, and a mutation at codon 802 of Pol conferred resistance to ganciclovir and foscarnet. This case illustrates the development of multidrug resistance during prolonged exposure to antiviral therapy for CMV and cross-resistance arising from point mutations in the CMV Pol gene.

An Outbreak of Pneumocystis carinii Pneumonia in Homosexual Men

Pneumocystis carinii pneumonia has rarely been reported in previously healthy persons over the age of 6 months. Five cases of P. carinii pneumonia in adult homosexual men, confirmed by biopsy results, are reported. All five patients were seropositive when tested for antibodies to cytomegalovirus and four had evidence of active concurrent cytomegalovirus infections. Kaposis sarcoma was shown in two of the patients and one had possible Pneumocystis infection of the central nervous system as well as P. carinii pneumonia. Three patients had second episodes of Pneumocystis pneumonia. Four of the five patients have died. Past or concurrent cytomegalovirus infection and homosexuality were the only common epidemiologic features in all five patients.

Cytomegalovirus Infections in Homosexual Men: An Epidemiological Study

Levels of cytomegalovirus antibody (IgG and IgM) were measured and urine viral cultures were done in 237 homosexual men over a mean period of 14.1 months. The initial prevalence of cytomegalovirus IgG antibody was 86.9%. By the 9th month of follow-up, 71% of serosusceptible men had become infected with cytomegalovirus. During the study period cytomegaloviruria was noted in 32% of seropositive men. Cytomegalovirus IgM antibody was intermittently present in the serum of 95% of IgG-seropositive men, suggesting that frequent reactivation of latent infection or reexposure to exogenous virus had occurred. Of seven sexual practices investigated, only passive anal-genital intercourse correlated with the acquisition of cytomegalovirus infection (p = 0.008).

A Randomized, Double-Blind, Placebo-Controlled Trial of Cidofovir Gel for the Treatment of Acyclovir-Unresponsive Mucocutaneous Herpes Simplex Virus Infection in Patients with AIDS

The safety and efficacy of cidofovir gel for treatment of acyclovir-unresponsive herpes simplex virus infections in AIDS patients was evaluated in a randomized, double-blind, multicenter trial. Cidofovir (0.3% or 1%) or placebo gel was applied once daily for 5 days. Ten of 20 cidofovir-treated and none of 10 placebo-treated patients had complete healing or >50% decreased area (P = .008); 30% of cidofovir-treated patients versus 0 placebo recipients had complete healing (P = .031). Viral shedding ceased in 13 (87%) of 15 cidofovir-treated and 0 of 9 placebo-treated patients (P = .00004). For cidofovir-treated patients, median time to complete or good response was 21 days, and median time to negative viral culture was 2 days (P = .025, P = .0001, respectively). Median lesion area decreases were 58% for cidofovir-treated versus 0 for placebo-treated patients (P = .005), and mean pain score changes were -1.84 versus -0.34 (P = .042). Application site reactions occurred in 25% of cidofovir-treated and 20% of placebo-treated patients; none was dose-limiting. Cidofovir therapy provided significant benefits in lesion healing, virologic effect, and pain reduction.

Phase I Dose Escalation Trial Evaluating the Pharmacokinetics, Anti-Human Cytomegalovirus (HCMV) Activity, and Safety of 1263W94 in Human Immunodeficiency Virus-Infected Men with Asymptomatic HCMV Shedding

ABSTRACT 1263W94 [maribavir; 5,6-dichloro-2-(isopropylamino)-1,β-l-ribofuranosyl-1-H-benzimidazole] is a novel benzimidazole compound for treatment of human cytomegalovirus (HCMV) infection and disease, with potent in vitro activity against HCMV and good oral bioavailability. A phase I study was conducted to determine the pharmacokinetics (PK), anti-HCMV activity, and safety of 1263W94 administered as multiple oral doses to human immunodeficiency virus type 1-infected adult male subjects with asymptomatic HCMV shedding. Subjects received one of six dosage regimens (100, 200, or 400 mg three times a day, or 600, 900, or 1,200 mg twice a day) or a placebo for 28 days. 1263W94 demonstrated linear PK, with steady-state plasma 1263W94 profiles predictable based on single-dose data. 1263W94 was rapidly absorbed following oral dosing, and values for the maximum concentration of the drug in plasma and the area under the concentration-time curve increased in proportion to the dose. 1263W94 demonstrated in vivo anti-HCMV activity in semen at all of the dosage regimens tested, with mean reductions in semen HCMV titers of 2.9 to 3.7 log10 PFU/ml among the four regimens evaluated for anti-HCMV activity. 1263W94 was generally well tolerated; taste disturbance was the most frequently reported adverse event over the 28-day dosing period.

Summary of the international consensus symposium on advances in the diagnosis, treatment and prophylaxis of cytomegalovirus infection

CMV infection and CMV disease can be difficult to differentiate and the diagnosis is usually based on a compatible clinical picture and the results of a diagnostic test for CMV. The only exception to this rule is in HIV-infected patients where fundoscopy is sufficient to diagnose CMV retinitis. Of the current diagnostic tests, qualitative and quantitative PCR, branched DNA and Hybrid Capture, are the most promising. The pp65 antigenemia assay has the disadvantage of being more labor-intensive than the DNA based tests. Preliminary data show that a positive qualitative PCR in a HIV-infected patient has a predictive value for the development of CMV retinitis. However, of the patients positive by qualitative PCR, those with high viral loads in quantitative PCR were at the greatest risk of CMV disease. This might make it possible to identify with great certainty the patients who will go on to develop CMV retinitis, thereby decreasing the number of patients eligible for preemptive or prophylactic therapy and increasing the cost-benefit of this therapeutic measure. Quantitative test might also be useful in monitoring response to therapy, but randomized trials comparing the test are needed. Prophylactic antiviral agents should not be used in seronegative transplant recipients receiving organs from seronegative donors. In high-risk transplant recipients, ganciclovir should be used. CMV vaccines are useful for the protection of babies from CMV seronegative mothers against congenital CMV disease. It also may be useful in seronegative transplant recipients receiving a seropositive donor organ, although the benefit of chemo prophylaxis may surpass that of vaccine. HIV-infected patients with CMV retinitis who relapse under either ganciclovir or foscarnet benefit from subsequent combination therapy, rather than switching to the other drug. However, the cost is high in terms of quality of life. Intravitreal therapy for CMV retinitis is very efficacious, suggesting that drug delivery is a problem in systemic therapy. However, intravitreal therapy does not protect against the development of CMV retinitis in the contralateral eye or from CMV disease elsewhere. Therefore, systemic therapy should be added. CMV disease of the CNS should be diagnosed early and treated agressively, possible with combination therapy. A diagnosis of CMV disease should be based on a compatible clinical picture and the demonstration of CMV in CSF by DNA or antigen assays which are more sensitive than culture.