Phase I study of low-dose zidovudine and acyclovir in asymptomatic human immunodeficiency virus seropositive individuals.

PURPOSE: The combination of zidovudine and acyclovir has shown in vitro antiretroviral activity and led to short-term improvement in patients with symptomatic human immunodeficiency disease (HIV) disease. We performed a phase I study of zidovudine (500 mg/day) plus acyclovir (2 or 4 g/day) in asymptomatic HIV-seropositive men to investigate pharmacokinetics, safety, tolerance, and immunologic effects of the combination. SUBJECTS AND METHODS: Fifty HIV-seropositive homosexual or bisexual men from the San Francisco City Clinic Cohort Study were recruited for the study; of these, 20 met the eligibility criteria. Treatment with zidovudine and acyclovir was open label. Pharmacokinetic, virologic, immunologic, and clinical data were collected periodically over a 24-week period. RESULTS: Pharmacokinetic analysis showed no drug interaction. The combination was generally well tolerated, and hematologic parameters remained stable through 24 weeks. There were no significant changes in total lymphocytes, T4 lymphocytes, overall skin test reactivity, or ability to culture virus from peripheral blood. CONCLUSION: This combination of agents is safe in this population for at least six months. Conclusions about long-term tolerance and efficacy await the results of larger trials with longer follow-up.

Antiviral susceptibilities of herpes simplex virus isolates from infants with recurrent mucocutaneous lesions after neonatal infection.

Recurrent mucocutaneous lesions occur in many infants after completion of antiviral therapy of neonatal herpes simplex virus (HSV) infection. To determine whether these recurrences were caused by viruses that had become resistant to acyclovir or vidarabine, we tested the antiviral susceptibilities of 22 pretherapy and 32 posttherapy HSV isolates from 22 infants younger than 3 months of age. Sixteen had been treated with acyclovir and six with vidarabine. Antiviral susceptibilities were measured by an enzyme-linked immunosorbent assay and are expressed as the 50% inhibitory dose. All HSV isolates had a 50% inhibitory dose for acyclovir of less than 1.0 micrograms/ml. The mean vidarabine 50% inhibitory dose was 11.4 micrograms/ml for pretherapy isolates and 8.9 micrograms/ml for posttherapy isolates. Antiviral therapy did not select for recurrences with HSV resistant to acyclovir or vidarabine.

Survival experience among patients with AIDS receiving zidovudine. Follow-up of patients in a compassionate plea program.

Through a compassionate plea program (Treatment Investigational New Drug), 4805 patients with acquired immunodeficiency syndrome who previously had experienced Pneumocystis carinii pneumonia (PCP) received zidovudine (Retrovir, formerly azidothymidine). Overall survival at 44 weeks after initiation of therapy was 73% (+/- 2.1%). A positive association was found between survival and pretherapy clinical status as defined by hemoglobin level, functional ability, and stage of disease as measured by time since diagnosis of PCP. For patients with baseline hemoglobin levels of 120 g/L or greater, Karnofsky scores of 90 or greater, and PCP diagnosis within 90 days prior to initiation of therapy, 44-week survival was 88%. Adverse clinical experiences associated with zidovudine therapy were consistent with those from a double-blind, placebo-controlled trial. Survival experience of this large and diverse cohort is consistent with, and extends data from, this clinical trial. Comparison with available natural history data suggests that zidovudine therapy is associated with increased 44-week survival of post-PCP patients with acquired immunodeficiency syndrome.

Effect of zidovudine on serum human immunodeficiency virus core antigen levels. Results from a placebo-controlled trial.

We assessed the effect of antiviral therapy on serum human immunodeficiency virus core antigen (HIV-Ag) levels in patients enrolled in the phase II trial on zidovudine for acquired immunodeficiency syndrome (AIDS) and AIDS-related complex. Human immunodeficiency virus core antigen was detected in 45% of subjects at entry (59% with AIDS and 37% of patients with AIDS-related complex). Median HIV-Ag levels in zidovudine-treated subjects fell from 111 pg/mL at entry to 46 pg/mL at four weeks, while levels in placebo recipients did not change significantly. Decline in HIV-Ag in zidovudine recipients was sustained through 16 weeks of treatment and was significantly different from the placebo group. Anti-p24 antibody levels did not change in either group. We conclude that in patients with HIV-antigenemia changes in HIV-Ag level are an important marker of anti-retroviral activity.

Chronic suppression for six months compared with intermittent lesional therapy of recurrent genital herpes using oral acyclovir: effects on lesions and nonlesional prodromes.

Forty-seven patients with frequently recurrent genital herpes were treated with 200 mg of acyclovir or placebo capsules taken orally three times daily for six months; the drug was then withdrawn. Active lesional events were treated with open-labeled 200-mg acyclovir capsules five times daily for five days during the six months of suppression and for six months thereafter if the patient returned to the clinic for culture and treatment. During the six months of treatment, seven of 24 acyclovir recipients and none of 23 placebo recipients reported no lesions (P less than 0.01), while 17 of 24 acyclovir and none of 23 placebo recipients failed to return for lesion assessment (P less than 0.0001). The median time to first recurrence was 72 days in the acyclovir recipients vs. 14 days in placebo recipients (P less than 0.0001). Home-recorded prodromes without lesion development were common in both groups but occurred more often in the acyclovir-treated group (P less than 0.05). During follow-up all patients experienced lesional episodes, and no differences could be detected between the acyclovir- and the placebo-treated groups. Resistance to acyclovir was not encountered either before, during, or after suppression by this drug. Adverse events were not significantly different between the groups. We conclude that suppression by oral acyclovir of frequently recurrent genital herpes remains effective for at least six months. Nonlesional prodromes have undetermined significance but are more common during acyclovir suppression.

HIV-1 inhibition by azidothymidine in a concurrently randomized placebo-controlled trail.

Two independent measures of human immunodeficiency virus type 1 (HIV-1) infection, virus isolation, and serum levels of p24 antigen were evaluated in a double-blind randomized clinical trial of the safety and efficacy of a nucleoside analogue, 3'-azido-3'-deoxythymidine (AZT) versus placebo in a single center. Pretreatment studies from 38 AIDS and AIDS-related complex (ARC) patients were comparably positive for virus isolation from their lymphocytes; all patients were qualitatively virus positive. Before AZT treatment, there was significantly decreased virus recovery in patients with higher numbers of CD4-positive lymphocytes. Within 1 month of AZT therapy, the time in culture required to register virus positivity was increased markedly in the AZT-treated group, and over the following several months progressive diminution in virus recovery was noted. Similar changes were not seen in patients concurrently receiving placebo treatment. Before treatment, 16 of 20 and 12 of 16 patients in the AZT and placebo groups, respectively, were p24 antigen positive. Marked reduction in serum p24 levels were noted in 11 of 16 (69%) of the p24 antigen-positive AZT-treated patients compared to 3 of 12 (25%) of the p24 antigen-positive placebo-treated patients (p = 0.02). There was a marked virologic response in 14 of 20 (70%) of the AZT-treated patients compared to 4 of 18 (22%) placebo-treated patients (p = 0.004). A higher frequency of positive clinical and immunological effects also were noted in the AZT-treated patients relative to placebo-treated patients (p = 0.02 and p = 0.06, respectively).

Nucleotide sequence changes in thymidine kinase gene of herpes simplex virus type 2 clones from an isolate of a patient treated with acyclovir.

To identify the nucleotide changes that occur in drug-induced thymidine kinase (TK) mutants of herpes simplex virus type 2 (HSV-2), we compared the nucleotide sequences of the tk genes of two mutant HSV-2 clones isolated from a patient who had been treated with acyclovir [9-(2-hydroxyethoxymethyl)guanine; ACV] with the nucleotide sequence of the parental TK+ HSV-2(8703) strain isolated from the same patient. One of the mutants, TK-altered (TKA) HSV-2(9637), was ACV resistant but induced the incorporation of [14C]thymidine into the DNA of infected rabbit skin cells. The nucleotide sequence of the tk gene of mutant TKA HSV-2(9637) had a single change (G to A) at nucleotide 668, which would cause an arginine-to-histidine substitution at amino acid residue 223 of the TK polypeptide. The second ACV-resistant mutant, TK- HSV-2(8710), did not induce detectable incorporation of [14C]thymidine into the DNA of infected rabbit skin cells. This mutant exhibited a deletion of a single base at nucleotide 217 of its nucleotide sequence. This deletion would cause a frameshift mutation at amino acid residue 73 and chain termination at amino acid residue 86 of the TK polypeptide. The nucleotide sequence of TK+ HSV-2(8703) was the same as that of the laboratory strain, TK+ HSV-2(333). The nucleotide sequence of a bromodeoxyuridine-resistant TK- HSV-2(333) mutant of TK+ HSV-2(333) also exhibited a single-base deletion, but at nucleotide 439. This deletion would cause a frameshift mutation at amino acid residue 147 and chain termination at amino acid residue 182. The frameshift mutations of TK- HSV(8710) and TK- HSV-2(333), respectively, occurred in sequences in which C was repeated three times and G was repeated seven times. The results raise the possibility that TK- frameshift mutations of HSV-2 may be common.

Suppression of mouse viraemia and retroviral disease by 3'-azido-3'-deoxythymidine.

The retroviruses human T-cell lymphotrophic virus-I (HTLV-I) and HTLV-III/LAV (lymphadenopathy-associated virus) are clearly linked to human diseases. Patients with HTLV-I-positive neoplasms may respond transiently to traditional chemotherapy, but are not cured. For patients with acquired immune deficiency syndrome (AIDS) there is no curative therapy. In retroviruses of different species, viral propagation crucially depends on reverse transcriptase, an enzyme not present in normal mammalian cells and different from mammalian DNA polymerases, making it a target for specific inhibition. Reverse transcriptase has been well conserved through evolution: an LAV isolate contained a 250-amino-acid-long domain, presumably the reverse transcriptase core sequence, which has 21% homology to Moloney murine leukaemia virus (MoMLV). Because HTLV-III infects only humans and chimpanzees, we substituted murine retroviruses for in vivo evaluation of candidate anti-AIDS drugs after ascertaining similar inhibition in vitro of HTLV-III and MLVs, which were chosen for their short incubation time. The triphosphate of 3'-azido-3'-deoxythymidine (AZT) is incorporated into complementary DNA by retroviral reverse transcriptase, causing premature chain termination. Here we show that chronic AZT treatment of mice infected with Rauscher murine leukaemia virus complex (RLV) prevents infection of splenocytes and development of splenomegaly, and suppresses viraemia if started soon after inoculation. Starting AZT late in the course of disease still leads to significant prolongation of life; anaemia, however is a significant side-effect. By analogy, AZT may have a role in preventing retroviral disease in humans if started early after infection, and it may lead to significant survival gains even if started later in the course of disease.

NIH Conference. Herpes simplex virus infection: biology, treatment, and prevention.

Herpes simplex viruses cause common mucocutaneous infections, but many aspects of their epidemiology and transmission are incompletely defined. Although the incidence of oral herpes remains relatively unchanged, the incidence of genital herpes is increasing significantly. Definitive diagnosis of herpes remains dependent on virus isolation, but techniques involving direct examination of clinical specimens are increasingly sensitive and may simplify and speed diagnosis. With the advent of acyclovir, effective therapy and suppression of infection are feasible for immunodeficient and selected normal patients. Unanswered questions remain regarding the long-term safety of acyclovir and the potential for emergence of clinically significant drug resistance. No effective vaccines are yet available for herpes virus infections. Promising strategies for vaccine development include preparation of immunogenic proteins, engineering of specially attenuated live virus strains, and incorporation of selected herpes genes into live vaccinia virus vectors.

Viral resistance, clinical experience.

Over 1500 herpes simplex virus isolates from over 600 patients have been examined in the Wellcome Research Laboratories during the past 5 years using the dye uptake method in Vero cells to determine acyclovir sensitivity. No significant change in sensitivity of those isolates to acyclovir has been noted during that period, and the few isolates whose sensitivity significantly diminished during therapy were generally not associated with a clinical lack of response to therapy. In patients who were severely immunocompromised and who had received prolonged or repeated courses of therapy, however, less sensitive viruses were occasionally associated with poorly healing ulcers. The significance of these findings are discussed, as are problems in the interpretation of results of in vitro antiviral sensitivity testing and their extrapolation to clinical practice.