Antiviral chemotherapy and chemoprophylaxis.

Antiviral compounds have been developed for use in chemoprophylaxis and chemotherapy of a variety of infections in humans, including those caused by influenza viruses, respiratory syncytial virus, and herpesviruses. The efficacy of several of these compounds has been demonstrated in rigorously controlled trials. Advances in molecular virology have led to the identification of biochemically defined, virus-specific functions that serve as appropriate targets for the future development of antiviral compounds. Clinical investigators and practicing physicians are now confronting questions previously raised with the use of antibacterial antibiotics. These questions concern appropriate routes of administration for antiviral compounds, optimal dosage regimens, risks of long-term prophylaxis, and the emergence of resistant organisms.

A Pharmacogenomics Clinical Decision Support Service Based on FHIR and CDS Hooks.

OBJECTIVES: Pharmacogenomics (PGx) is often considered a low-hanging fruit for genomics-electronic health record (EHR) integrations, and many have expressed the notion that drug-gene interaction checking might one day become as much a commodity in EHRs as drug-drug and drug-allergy checking. In addition, the U.S. Office of the National Coordinator has recognized the trend toward storing complete sequencing data outside the EHR in a Genomic Archiving and Communication System (GACS) and has emphasized the need for "pilots that test Fast Healthcare Interoperability Resources (FHIR) Genomics for GACS integration with EHRs." We sought to develop a PGx clinical decision support (CDS) service, leveraging the emerging FHIR and CDS Hooks standards, and based on an assumption that pharmacogene sequencing data would be stored alongside the EHR in a GACS. METHODS: We developed a PGx CDS service as a functional prototype. The service is triggered by a medication order in the EHR. When evoked, the service looks for relevant genetic data in a GACS and returns corresponding recommendations back to the ordering clinician. Where the patient has no genetic data on file, the service can recommend pretreatment genetic testing where applicable. RESULTS: Overall, we were able to meet our objectives and deploy a functional prototype, interfaced with a commercial EHR. We identified several areas where FHIR or CDS Hooks lacked necessary semantics or have implementation ambiguity. Primary FHIR challenges included multiple ways to say the same thing, which exacerbated the complexity of variant to allele conversion and lack of representation of deoxyribonucleic acid region(s) studied. Primary CDS Hooks challenges included the complexity of executing an authenticated query against one system (GACS) upon being triggered by a different system (the EHR), and limitations in the types of actionable recommendations that can be returned to the EHR. CONCLUSIONS: In conclusion, we have found that PGx CDS based on FHIR and CDS Hooks appears to represent a promising means of genomics-EHR integration. More real-world testing along with a set of use-case driven GACS interface requirements will push us closer to the U.S. National Human Genome Research Institute vision of a plug-in PGx app.

Serum antibody levels as risk factors in the dissemination of herpes zoster.

Serum antibody levels against varicella-zoster virus (VZV) were examined by immune adherence hemagglutination assay (IAHA), indirect fluorescent antibody (IFA) assay, and complement fixation techniques in 67 immunocompromised patients with localized and disseminated herpes zoster. In the serum obtained initially, undetectable IAHA titers were found in 56.5% of the patients with disseminated zoster compared with 18.2% of those with localized zoster. When serum obtained within the first seven days of illness was analyzed, undetectable IAHA titers and IFA titers of less than 32 were noted in 77.8% of those with disseminated zoster but in only 18.5% of those with localized disease. Peak serum antibody titers in patients with disseminated zoster were eventually equal to or greater than those in localized zoster. The patient groups were comparable in age, underlying disease, and therapy, although Hodgkin's disease was more frequent in patients with disseminated zoster. Thus, the absent IAHA or low IFA levels of circulating antibody early in illness were highly significant risk factors in dissemination of virus in herpes zoster.

Pneumonic and nonpneumonic forms of legionellosis. The result of a common-source exposure to Legionella pneumophila.

Two male maintenance workers contracted legionellosis while cleaning the interior of a cooling tower contaminated with Legionella pneumophila. In one man severe, life-threatening Legionnaires' disease developed, whereas the other experienced a comparatively mild, self-limiting illness that was consistent with previous descriptions of cases of Pontiac fever. This report represents the first documentation of the development of both of these syndromes following exposure to a common source of the organism. The implications of this observation for the pathogenetic mechanisms that underly the different clinical manifestations of legionellosis are discussed.

Zidovudine compared with didanosine in patients with advanced HIV type 1 infection and little or no previous experience with zidovudine. AIDS Clinical Trials Group.

BACKGROUND: We conducted a trial to compare treatment with zidovudine or didanosine in patients with advanced human immunodeficiency virus type 1 (HIV-1) infection who had received little or no previous therapy with zidovudine. METHODS: Six hundred seventeen patients with acquired immunodeficiency syndrome (AIDS), advanced AIDS-related complex (CD4 cell count, < or = 0.30 x 10(9)/L [300/microL]), or asymptomatic HIV (CD4 cell count, < or = 0.20 x 10(9)/L) received zidovudine, 500 mg/d of didanosine, or 750 mg/d of didanosine in a randomized, double-blind allocation, with cross-over to alternative medication after development of an end point or serious toxic effect. To be eligible, patients must have received either no or up to 16 weeks of zidovudine therapy before entry into the study. Primary end points were development of a new AIDS-defining event or death. Secondary clinical end points were new or recurrent AIDS-defining events, or death, and survival. RESULTS: In the study as a whole, there were no differences in the relative risks (RRs) of the development of end points between treatment groups. However, there was a strong interaction between the relative efficacies of zidovudine and didanosine and previous experience with zidovudine. Among 380 patients with no previous zidovudine therapy, zidovudine was more effective than 750 mg/d of didanosine (RR, 1.43; 90% confidence interval [CI], 1.02 to 2.00), with a similar trend for zidovudine compared with 500 mg/d of didanosine (RR, 1.21; 90% CI, 0.86 to 1.71). However, among 118 patients with more than 8 weeks but no more than 16 weeks of previous zidovudine therapy, 500 mg/d of didanosine was more effective than zidovudine (RR, 0.48; 90% CI, 0.27 to 0.86); there was a similar trend for increased effectiveness of 750 mg/d of didanosine compared with zidovudine (RR, 0.61; 90% CI, 0.36 to 1.03). Among 119 patients who had some but no more than 8 weeks of previous zidovudine therapy, there were no significant differences among the treatment arms. Similar findings were noted in the analysis of the two secondary clinical end points. No significant differences were found in efficacy between the groups receiving 500 and 750 mg/d of didanosine. The major toxic effect associated with zidovudine was hematopoietic (granulocytopenia) and that associated with didanosine was pancreatitis (dosage, 750 mg/d). CONCLUSIONS: In patients with advanced HIV disease, zidovudine appears to be more effective than didanosine as initial therapy; however, some patients with advanced HIV disease may benefit from a change to didanosine therapy after as little as 8 to 16 weeks of therapy with zidovudine.

Health level seven interoperability strategy: big data, incrementally structured.

OBJECTIVES: Describe how the HL7 Clinical Document Architecture (CDA), a foundational standard in US Meaningful Use, contributes to a "big data, incrementally structured" interoperability strategy, whereby data structured incrementally gets large amounts of data flowing faster. We present cases showing how this approach is leveraged for big data analysis. METHODS: To support the assertion that semi-structured narrative in CDA format can be a useful adjunct in an overall big data analytic approach, we present two case studies. The first assesses an organization's ability to generate clinical quality reports using coded data alone vs. coded data supplemented by CDA narrative. The second leverages CDA to construct a network model for referral management, from which additional observations can be gleaned. RESULTS: The first case shows that coded data supplemented by CDA narrative resulted in significant variances in calculated performance scores. In the second case, we found that the constructed network model enables the identification of differences in patient characteristics among different referral work flows. DISCUSSION: The CDA approach goes after data indirectly, by focusing first on the flow of narrative, which is then incrementally structured. A quantitative assessment of whether this approach will lead to a greater flow of data and ultimately a greater flow of structured data vs. other approaches is planned as a future exercise. CONCLUSION: Along with growing adoption of CDA, we are now seeing the big data community explore the standard, particularly given its potential to supply analytic en- gines with volumes of data previously not possible.

Pancreatitis and pancreatic dysfunction in patients taking dideoxyinosine.

OBJECTIVE: To describe the incidence, clinical characteristics and dose relationship of dideoxyinosine (ddI)-associated pancreatitis. DESIGN: Patients enrolled in a Phase I dose escalation trial of ddI [AIDS Clinical Trials Group (ACTG) 064] were evaluated for signs and symptoms of pancreatic dysfunction. SETTING: Two ACTG sites. PATIENTS: Forty-four patients with AIDS or AIDS-related complex (ARC) and a CD4 cell count less than or equal to 400 x 10(6)/l. MAIN OUTCOME MEASURES: Seven patients developed pancreatitis that lasted from 1 to 7 weeks and varied in severity from mild to life-threatening. Seven other patients had evidence of hyperamylasemia or hypertriglyceridemia. Six patients who developed pancreatitis were able to tolerate rechallenge with lower doses of ddI. RESULTS: Development of pancreatitis correlated with cumulative dose of ddI but not with stage of disease or concomitant medications. Cumulative dose was not significantly associated with development of hyperamylasemia or hypertriglyceridemia in patients without clinical pancreatitis. CONCLUSIONS: The development of pancreatitis in AIDS or ARC patients receiving ddI varies in severity and time course and is associated with cumulative dose. Patients who develop pancreatitis may be able to tolerate therapy with a lower dose after resolution of their symptoms. Patients receiving ddI require careful monitoring for the development of this complication.

Pharmacokinetics of didanosine in patients with acquired immunodeficiency syndrome or acquired immunodeficiency syndrome-related complex.

The pharmacokinetics of didanosine (2',3'-dideoxyinosine) after intravenous and oral administration were evaluated in an open, escalating-dose phase I study in patients with acquired immunodeficiency syndrome (AIDS) or severe AIDS-related complex. Didanosine was administered twice a day for 2 weeks as an intravenous infusion of 60 minutes duration at doses ranging from 0.4 to 16.5 mg/kg, followed by 4 weeks of oral treatment at twice the intravenous dose. Serial blood and urine samples were obtained on the first and final day of intravenous administration and after the first oral dose, as well as at steady state. Didanosine demonstrated linear pharmacokinetic behavior over the dose ranges of 0.4 to 16.5 mg/kg intravenously and 0.8 to 10.2 mg/kg orally. There was no indication of significant changes in pharmacokinetic parameters with repeated administration. The apparent elimination half-life after oral administration was approximately 1.4 hour. Renal clearance values exceeded the glomerular filtration rate, indicating that active tubular secretion of didanosine occurs. Bioavailability of didanosine when administered as a solution with an antacid was approximately 43% for doses from 0.8 to 10.2 mg/kg in patients with AIDS and advanced AIDS-related complex. Bioavailability of didanosine from the citrate-phosphate-buffered solution, the formulation currently used in phase II and expanded access studies, was comparable to the formulation used in the phase I trials.

Extended follow-up of peripheral neuropathy in patients with AIDS and AIDS-related complex treated with dideoxyinosine.

Neuropathic complaints were frequently observed in a Phase I study of dideoxyinosine (ddI) in 44 patients with AIDS and AIDS-related complex. Ten patients (23%) were thought to have a ddI-related peripheral neuropathy. The symptoms were primarily sensory, and there was limited motor involvement. The sensory symptoms improved in all patients with discontinuation of ddI. Some patients tolerated reintroduction of ddI at lower doses without significant recurrence of the neuropathic symptoms. Although the neuropathy was usually seen in patients taking higher doses of ddI than used in current treatment protocols, clinicians must be aware of this potential toxicity as more human immunodeficiency virus-infected patients are being treated with ddI.

Meta-analysis of five randomized controlled trials comparing continuation of zidovudine versus switching to didanosine in HIV-infected individuals.

A meta-analysis of the original data from 2411 patients in the ACTG 116A, ACTG116B/117, ACTG175, BMS010 and CTN002 trials was conducted to improve the estimate of the effect of switching from zidovudine to didanosine on rates of clinical progression, to better quantify the rates of neurological events (including AIDS dementia and peripheral neuropathy) and to examine the effects of switching from zidovudine to didanosine among women and racial subgroups. In total, 1012 patients received zidovudine therapy, 557 received high-dose didanosine and 842 received didanosine. The median duration of follow-up was 15 months. Ninety-one percent of patients were male, 78% were white, mean age was 36.5 years. The median CD4 count was 195 cells/mm3 (range: 0-762) and the median duration of prior zidovudine therapy was 14 months (range: 0.1-94). There were 336 deaths and 686 new AIDS-defining illnesses (ADIs) or deaths. After stratification by study and adjusting for baseline CD4 count and presence of an AIDS diagnosis prior to baseline, the relative risks of death associated with switching from zidovudine to high-dose didanosine or to didanosine were 0.94 (P = 0.64) and 0.77 (P = 0.07), respectively. The relative risks of a new ADI or death associated with switching from zidovudine to high-dose didanosine and didanosine were 0.78 (P = 0.01) and 0.66 (P = 0.0001), respectively. There were 21 documented cases of AIDS dementia complex (ADC) during the entire follow-up period. The rates per 100 person years of follow-up were 0.70, 0.65 and 0.41 for the zidovudine, high-dose didanosine and didanosine arms, respectively. There were no significant differences in risks of ADC between treatment arms (zidovudine versus high-dose didanosine: P = 0.30, zidovudine versus didanosine: P = 0.97, didanosine versus high-dose didanosine: P = 0.41). Our data confirm a clinical benefit and CD4 increase associated with a switch from zidovudine to didanosine therapy. No statistical differences were detected between doses of didanosine with respect to survival or progression to a new ADI or death. Furthermore, there was no statistical difference in the frequency of ADC between treatment arms.

Herpes zoster at the NIH: a 20 year experience.

One hundred and seven cases of herpes zoster in a hospitalized population with a variety of illnesses during a 20 year period were reviewed. Zoster occurred throughout the year, without seasonal predominance, and was most frequent in lymphoproliferative malignancy. In the majority, lesions were confined to the skin in one or more adjacent dermatomes (localized zoster) and were most frequent in the thoracic region. In 15 per cent of the cases, cutaneous dissemination of the lesions developed; this occurred four to 11 days after the onset of dermatomal lesions, and in one-third of these there was central nervous system involvement. Dissemination of zoster, however, directly resulted in only one death. Predisposing factors for zoster included local irradiation and, occasionally, surgery in subsequently involved areas. There were trends for more frequent splenectomies in patients with Hodgkin's disease in whom zoster subsequently developed, and for more frequent corticosteroid therapy in patiens with disseminated zoster. Advanced stage of Hodgkin's disease, in itself, was not associated with development of zoster, and the onset of zoster did not herald a poor prognosis for the underlying disease. Herpes zoster was, thus, largely a source of increased morbidity rather than mortality in the population studied, and multiple factors appeared to predispose to the development of zoster in this group of patients.

Lymphocyte responses to herpes simplex virus isolates from patients with primary and recurrent herpes simplex genitalis.

The ability of herpes simplex (HSV) isolates from patients with herpes simplex genitalis (HSG) to induce lymphocyte transformation in cells from unrelated, healthy, seropositive donors was examined in a standard lymphocyte transformation assay. All HSV isolates were obtained, before the initiation of therapy, from patients who were enrolled in a placebo-controlled trial of acyclovir in the treatment of HSG. Isolates from patients with primary infections were used, as well as those from patients with frequent (eight or more episodes per year) or infrequent (two or fewer per year) recurrent disease. Blastogenic responses to isolates from patients with infrequent HSG recurrences were significantly less than those to isolates from patients either primary infections or frequent recurrences. No differences between the latter two groups of isolates were seen. These observations demonstrate that differences among naturally occurring HSV isolates exist as determined by this in vitro assay of host-virus interactions. Differences among strains may be important in the pathogenesis of HSV infections, particularly with respect to latency.

Viral gastroenteritis induced by the Hawaii agent. Jejunal histopathology and serologic response.

Peroral jejunal biopsies were performed in seven normal volunteer subjects prior to, 48 hours after and two weeks after the administration of the Hawaii agent of viral gastroenteritis. Light and electron microscopic examination revealed an intact mucosa with blunted villi, shortened and distorted microvilli, swollen mitochondria and intercellular edema. These histologic changes were seen only in acutely ill volunteer subjects and were absent two weeks after illness in three of four who were previously ill. This reversible lesion was similar to, but not identical with, that previously described in viral gastroenteritis induced by the Norwalk agent. Serum antibody increases in response to the Hawaii agent as measured by immune electron microscopy were present in three of four ill volunteer subjects and in none of three who remained well.

Controlled trial of oral acyclovir in the therapy of recurrent herpes simplex genitalis. A preliminary report.

A randomized, placebo-controlled, double-blind study was performed to evaluate the efficacy and toxicity of orally administered acyclovir in the treatment of patients with recurrent herpes simplex genitalis (HSG). A total of 107 patients from centers in Burlington, Vermont, and San Diego, California, were entered into the study within 48 hours of the onset of lesions. Patients who received acyclovir shed virus for 1.8 +/- 0.6 days (mean +/- SEM) compared with 2.8 +/- 1.2 days for those who received placebo. The duration of shedding from genital lesions of patients in the acyclovir-treated group was significantly less than from lesions of patients who received placebo (p = 0.016 by a logrank test). An analysis of the toxicity of the drug was performed in 52 of the study participants. Acyclovir was well-tolerated and no alterations were observed in measurements of bone marrow, liver, or kidney function. Orally administered acyclovir is a promising antiviral compound for the treatment of recurrent HSG.

Foodborne Snow Mountain agent gastroenteritis in a school cafeteria.

In 1984, an outbreak of gastroenteritis occurred at a school with 1,860 students in Brooklyn, NY. In a single-stage cluster sample of 375 students, 129 (34%) had illnesses that met our case definition of vomiting or diarrhea. The mean incubation period was 26 hours, and the mean illness duration was 24 hours. All case students had eaten in the cafeteria on at least one day between Nov 13 and 16, compared with 174/214 (81%) noncase students (P = 10(-8), Fisher exact test). Foods implicated were french fries (relative risk 1.7, 95% confidence limits 1.4, 2.0) and hamburgers (relative risk 1.6, 95%, confidence limits 1.2, 2.1). Two cafeteria employees had served those foods while affected by diarrhea. By a recently developed blocking enzyme-linked immunosorbent assay, six of 11 (55%) case students showed fourfold antibody increases between acute- and convalescent-phase serum samples for Snow Mountain agent, a Norwalk-like virus, compared with one of ten (10%) noncase students (P = .04, Fisher exact test). We strongly suspect, but cannot document conclusively, that the Snow Mountain agent was spread to students on a vector of hot foods contaminated by ill food handlers. Implicated foods conferred low relative risks and could only have accounted for 74% of cases of illness. The strong association between cafeteria exposure and illness, therefore, suggests that additional modes of spread occurred.

Children with influenza A infection: treatment with rimantadine.

Treatment with rimantadine of influenza in children and the potential development of resistance in clinical isolates associated with therapy have not been previously studied. We compared rimantadine to acetaminophen therapy in a controlled, double-blind study of 91 children with influenza-like illness. Of 69 children with proven influenza A/H3N2 infection, 37 received rimantadine and 32 received acetaminophen for five days. Children receiving rimantadine showed significantly greater reduction in fever and improvement in daily scores for symptoms and severity of illness during the first three days. Viral shedding also diminished significantly during the first two days but subsequently increased such that by days 6 and 7 the proportion of children shedding virus, as well as the quantity of virus shed, was significantly greater in the rimantadine group. During the seven-day study, of the 22 children in the rimantadine group with serial isolates tested, ten (45.5%) had resistant isolates compared with two (12.5%) of those with serial isolates in the acetaminophen group (P less than .03). Thus, of the total 37 children in the rimantadine group, 27% were found to have resistant isolated compared with 6% in the total group receiving acetaminophen (P less than .04). Furthermore, the mean inhibitory concentration of rimantadine increased with time in the rimantadine group (r = .4, P = .002) but not in the acetaminophen group. Rimantadine therapy, thus, appears to be significantly more effective than acetaminophen in ameliorating the clinical signs and symptoms of influenza in children. Treatment with rimantadine was also associated with increased viral shedding after the medication was discontinued and with the development of resistance in the clinical isolates, the significance of which is unknown.

Safety and immunogenicity of Env 2-3, a human immunodeficiency virus type 1 candidate vaccine, in combination with a novel adjuvant, MTP-PE/MF59. NIAID AIDS Vaccine Evaluation Group.

We investigated the safety and immunogenicity of a candidate HIV-1 vaccine, Env 2-3 (Chiron Biocine Co.), in combination with an adjuvant emulsion, MF59, with or without an additional immune modulator, MTP-PE 78 healthy HIV-1-seronegative adults. Sixteen subjects participated in a dose escalation study of MTP-PE in MF59 without Env 2-3, given at 0 and 1 months; 48 subjects participated in a study of a fixed dose of 30 micrograms of Env 2-3 in MF59 with increasing doses of MTP-PE (0, 5, 10, 25, 50, and 100 micrograms), and 14 subjects participated in a study of 100 micrograms of Env 2-3 in MF59 without MTP-PE. Subjects were assigned to study groups under a randomized, double-blind allocation. Subjects received immunization at 0, 1, and 6 months, and had the option of receiving a fourth dose at 12-18 months. Env 2-3 in MTP-PE/MF59 was associated with significant reactogenicity, in that severe, although self-limited systemic and/or local reactions occurred in 15 of 30 vaccinees. In contrast, Env 2-3 in MF59 without MTP-PE was relatively well tolerated, and severe local and/or systemic reactions occurred in only 2 of 18 subjects. Env 2-3 stimulated serum antibodies to HIV-1 envelope protein (gp120) as detected by Western blot in 39 of 43 subjects and to HIV-1 virus lysate by EIA in 28 of 43 subjects after three injections. The majority of subjects also developed EIA antibodies to recombinant gp120 (SF-2), gp120 (LAI), and V3 peptide (SF-2). Neutralizing antibodies to the homologous SF-2 strain developed in 30 of 43 and 27 of 34 subjects, and fusion inhibition antibodies in 25 of 43 and 15 of 36 subjects after three and four injections, respectively. Lymphoproliferative responses to the immunogen, Env 2-3 were observed in over 80% of the vaccinees examined, and CD4+ cytotoxic T cell activity directed against HIV-1 was noted transiently in 2 of 20 vaccinees. Addition of MTP-PE to Env 2-3 or increasing the dose of Env 2-3 from 30 to 100 micrograms did not augment immunogenicity. Env 2-3 in MF59 was well tolerated and immunogenic in HIV-1-seronegative individuals. The addition of MTP-PE significantly increased reactogenicity, but had little, if any, effect on immunogenicity.

A phase II study of two HIV type 1 envelope vaccines, comparing their immunogenicity in populations at risk for acquiring HIV type 1 infection. AIDS Vaccine Evaluation Group.

Several immunogens induce HIV-specific neutralization and in vitro lymphoproliferation in adults at low HIV-1 risk, but responses in persons at high HIV-1 risk are not known. We performed a multicenter, double-blinded, adjuvant-controlled trial with two gp120 vaccines in 296 HIV-1-uninfected volunteers, including 176 reporting higher HIV-1 risk activities. The immunogens were remarkably well tolerated. After three immunizations, 210 of 241 vaccinees (87%) developed neutralizing antibodies, which persisted in 59% after 2 years. The injection drug users receiving SF-2/gp120 had decreased antibody responses relative to the lower risk groups. Envelope-specific lymphoproliferation peaked after two immunizations, and 54% of vaccinees mounted a DTH reaction to gp120 after 4 years. In summary, these immunogens have low adverse reactogenicity and induce durable antibody and T cell responses to the prototype strains. Unexpected differences in antibody responses among diverse HIV-1 risk strata lend support to the conduct of expanded phase II trials in populations other than low-risk volunteers.

Field trial of rhesus rotavirus vaccine in infants.

Orally administered rhesus rotavirus vaccine (RRV) was evaluated in a placebo-controlled study in 176 infants (ages 2 to 4 months). Eighty-eight infants received a dose of 10(4) plaque-forming units of the vaccine, and 88 received the placebo. RRV was well-tolerated but mildly reactogenic in the 10 days after vaccination. There were mild febrile reactions (greater than or equal to 38 degrees C rectally) in 40% of the vaccinees and in 16% of the placebo recipients (P = 0.001). More of the vaccinees had loose stools than did the placebo recipients (P less than 0.05). RRV was immunogenic and induced a 4-fold or greater rise in serum neutralizing antibody responses in 67% of the vaccinees; however, breast-fed infants were less likely to develop a seroresponse than infants who were not breast-fed. Despite the good immunogenicity of RRV the overall incidence of rotavirus-associated illnesses was similar between the vaccine and placebo recipients. The failure of RRV in Rochester may be related to the fact that the circulating rotaviruses were predominantly serotype 1 and RRV is a serotype 3 rotavirus. Because the serotypes of rotavirus that predominate may vary from year to year, a polyvalent preparation may be necessary to provide effective vaccination against rotaviruses.

Didanosine (ddI) and zidovudine (ZDV) susceptibilities of human immunodeficiency virus (HIV) isolates from long-term recipients of ddI.

Thirty HIV isolates, obtained from 15 patients before and after receiving single drug therapy with didanosine (ddI), were examined for sensitivity to ddI and zidovudine (ZDV) using a peripheral blood mononuclear leukocyte (PBML)-based assay. Fourteen of the patients had ARC, one had AIDS and 12 had received previous therapy with ZDV. After a median of 1 year of ddI therapy, isolates were significantly less sensitive to ddI than were isolates obtained prior to therapy (P = 0.03). A decrease in ddI sensitivity was observed in ten of the 15 isolate pairs. In contrast to ddI susceptibilities, sensitivity to ZDV increased over the same period of time (P = 0.03). Additional isolates were obtained from four patients who received ddI monotherapy for 2 years. Three of these isolates demonstrated no change in ddI sensitivity compared to baseline. No correlation could be made in this study between development of decreased ddI sensitivity and serum p24 levels, CD4 counts, or clinical outcome. Decreased ddI sensitivity occurs frequently among HIV isolates obtained from long-term recipients of ddI. This decreased sensitivity is modest in degree and is of unknown clinical significance.