Drug-resistant HIV-1 in the semen of men receiving antiretroviral therapy with acute sexually transmitted infections

Sexually transmitted infections may enhance the sexual transmission of HIV-1. It is possible that loss of virological control in patients with such infections receiving antiretroviral therapy (ART) may even facilitate the transmission of drug-resistant HIV. We have recently demonstrated that in those on maximally suppressive ART this effect is reduced. We have examined the virus obtained from the blood plasma and seminal plasma of six HIV-1-infected men receiving poorly suppressive ART with acute urethritis for the presence of drug resistance-associated mutations. In four men with gonorrhoea the blood and seminal plasma HIV-1 had mutations conferring reduced susceptibility to one or more available drugs. In one of these men the viral load of drug-resistant virus in seminal plasma was 20-fold higher during gonorrhoea than following antibiotic treatment, with no change in blood plasma viral load. We conclude that in the presence of suboptimal ART, sexually transmitted infections may enhance the spread of drug-resistant HIV-1.

Drug resistance genotypes predict response to amprenavir-containing regimens in highly drug-experienced HIV-1-infected patients

We have undertaken a study of virological responses to amprenavir-containing antiretroviral regimens, during the expanded access programme within the UK. Ninety-five HIV-1-infected patients were included for which virological and immunological follow-up was available for 75, and baseline drug resistance data available for 51. These were highly drug-experienced patients, having previously received a median of nine antiviral drugs, within all available classes. Eighty-eight percent of patients had a virological response to the new regimen, with a median maximal decline of 1.45 log10 copies/ml, and 34% of patients reached <400 copies/ml on treatment. Although 68% of patients with resistance data had protease inhibitor resistance mutations, only 10% patients had key amprenavir resistance mutations, and virological response was predicted by the number of active drugs utilized in the amprenavir-containing regimen, as determined by the baseline genotypic resistance test. Other independent predictors of viral load decline were a higher baseline viral load and fewer previous antiviral drugs. We conclude that amprenavir can contribute to antiviral efficacy in salvage regimens, and that resistance testing may help to optimize its use in this scenario. New formulations of amprenavir, together with boosted regimens, may enhance the activity in the presence of protease inhibitor-resistant virus.

Drug-Resistant HIV-1 in the Semen of Men Receiving Antiretroviral Therapy with Acute Sexually Transmitted Infections

Sexually transmitted infections may enhance the sexual transmission of HIV-1. It is possible that loss of virological control in patients with such infections receiving antiretroviral therapy (ART) may even facilitate the transmission of drug-resistant HIV. We have recently demonstrated that in those on maximally suppressive ART this effect is reduced. We have examined the virus obtained from the blood plasma and seminal plasma of six HIV-1-infected men receiving poorly suppressive ART with acute urethritis for the presence of drug resistance-associated mutations. In four men with gonorrhoea the blood and seminal plasma HIV-1 had mutations conferring reduced susceptibility to one or more available drugs. In one of these men the viral load of drug-resistant virus in seminal plasma was 20fold higher during gonorrhoea than following antibiotic treatment, with no change in blood plasma viral load. We conclude that in the presence of suboptimal ART, sexually transmitted infections may enhance the spread of drug-resistant HIV-1.

Drug Resistance Genotypes Predict Response to Amprenavir-Containing Regimens in Highly Drug-Experienced HIV-1-Infected Patients

We have undertaken a study of virological responses to amprenavir-containing antiretroviral regimens, during the expanded access programme within the UK. Ninety-five HIV-1-infected patients were included for which virological and immunological follow-up was available for 75, and baseline drug resistance data available for 51. These were highly drug-experienced patients, having previously received a median of nine antiviral drugs, within all available classes. Eighty-eight percent of patients had a virological response to the new regimen, with a median maximal decline of 1.45 log10 copies/ml, and 34% of patients reached <400 copies/ml on treatment. Although 68% of patients with resistance data had protease inhibitor resistance mutations, only 10% patients had key amprenavir resistance mutations, and virological response was predicted by the number of active drugs utilized in the amprenavir-containing regimen, as determined by the baseline genotypic resistance test. Other independent predictors of viral load decline were a higher baseline viral load and fewer previous antiviral drugs. We conclude that amprenavir can contribute to antiviral efficacy in salvage regimens, and that resistance testing may help to optimize its use in this scenario. New formulations of amprenavir, together with boosted regimens, may enhance the activity in the presence of protease inhibitor-resistant virus.

Antibody response after RSV infection in children younger than 1 year of age living in a rural area of Mozambique

Serological responses have been studied in respiratory syncytial virus (RSV) infected children < 1 year of age attending the outpatient department of the Manhiça District Hospital (Mozambique). Molecular characterization of viral RNA in nasopharyngeal aspirates from the infected children indicated a high level of genetic uniformity among the infecting viruses, all of which belonged to a single genotype of RSV group A. A representative virus strain, Moz00, was isolated from one of the infants and was used, together with the group A strain A2 and the group B strain 8/60, as antigens in the quantification of infant antibody responses. In this study, 97.5% (39/40) and 96.4% (27/28) of infected children produced an antibody response against Moz00 detected by the membrane fluorescent antibody test (MFAT) and the neutralization test (NT), respectively. Seroconversion rates decreased when the A2 and 8/60 strains were used as antigen in MFAT (95.4% and 88.2%, respectively) or NT (81.8% and 54.5%, respectively), indicating that antibody responses had both group- and strain-specific components. Antibodies in convalescent sera of infected children were compared with maternally derived antibodies detected in a group of children also < 1 year of age, but with no evidence of RSV infection. The convalescent sera exhibited reduced neutralizing capacity when the 8/60 strain was used as antigen (P = 0.028), suggesting that the infant antibody response lacks neutralizing capacity against strains of the heterologous virus group. Restricted cross-reactivity and neutralizing capacity of antibodies generated by young children might be expected to induce only moderate protection in subsequent epidemics against genetically distant strains.

Human metapneumovirus in a haematopoietic stem cell transplant recipient with fatal lower respiratory tract disease

Respiratory viruses are increasingly recognized as a cause of pneumonitis following haematopoietic stem cell transplantation (HSCT). However, frequently, no pathogen is identified in cases of suspected viral pneumonia. Recently, a previously undescribed paramyxovirus, designated 'human metapneumovirus' (hMPV), was isolated from children with respiratory illness. We have detected hMPV as the sole pathogen in the nasopharyngeal aspirate of an HSCT recipient who succumbed to progressive respiratory failure following an upper respiratory prodrome. This report highlights the importance of further studies to elucidate the role of hMPV in causing respiratory illnesses in the HSCT population.

Analysis of HIV-1 variation in blood and semen during treatment and treatment interruption

The variability of populations of human immunodeficiency virus type 1 (HIV-1) in blood and semen, with respect to envelope and polymerase gene sequences, was examined longitudinally in a patient experiencing treatment failure, interruption of treatment, and successful reintroduction of therapy. During treatment failure, there was little evidence of compartmentalisation between blood and semen, with virus with identical resistance-associated mutations observed in both compartments and lack of clustering with respect to envelope gene sequences. After cessation of treatment, wild-type virus became the predominant population, displaying distinct envelope gene populations, indicating that wild-type virus had overgrown the resistant virus, rather than the resistant virus reverting to wild-type. Once successful therapy had been recommenced, it was possible to distinguish distinct populations of virus in the two compartments. These data support the hypothesis that the male genital tract represents a distinct HIV-1 reservoir.

Minimal variation in T-20 binding domain of different HIV-1 subtypes from antiretroviral-naive and -experienced patients

In-vitro differences in T-20 susceptibility among HIV-1 subtypes have been reported. We therefore studied the T-20 binding domain of a variety of virus subtypes from both antiretroviral-naive and -experienced patients. Minimal variation in the HR-1 region of gp41 was observed, especially within the region responsible for T-20 resistance. Any subtype differences in T-20 susceptibility do not appear to be related to HR-1 genetic variation.

Resistance-associated mutations in the human immunodeficiency virus type 1 subtype c protease gene from treated and untreated patients in the United Kingdom

This work reports the variability of human immunodeficiency virus type 1 (HIV-1) protease from treated and untreated patients infected with HIV-1 subtype C in the United Kingdom. The most common primary mutation observed in treated patients was L90M. D30N, M46I, V82A/F, and I84V were seen rarely. M36I and I93L mutations were observed in nearly all samples from both treated and untreated patients and so cannot be considered as resistance-associated mutations in this subtype.

Recombinant strains of HIV type 1 in the United Kingdom

Twenty-five recombinant (mosaic) HIV-1 genomes were detected among 151 samples comprising 118 non-B subtype sequences and 33 samples containing subtype B sequences. Seven of the 25 mosaic patterns were similar to characterized circulating recombinant forms (two A/E, four A/G, and one D/F) and one was a MAL-like A/D recombinant. Eighteen of the recombinants had evidence of subtype A sequences in at least one region of their genome. One sample was found to contain a novel recombinant form (pol F, env K). Two samples could not be characterized unambiguously as recombinant forms and a further one appeared to be a complex C/J/D/A genomic form. The majority of the mosaic genomes were recombinants between gag, pol, or env, whereas the C/J/D/A mosaic had cross-over breakpoints within pol. These findings suggest that almost 20% of non-B subtype isolates of HIV-1 circulating in the United Kingdom have mosaic genomes. This shows the diverse origin of HIV-1 strains circulating in the United Kingdom and may have implications for antiretroviral drug resistance.

Molecular epidemiology of respiratory syncytial virus

Human respiratory syncytial virus (RSV) is the major cause of lower respiratory tract disease in infants. It is unusual in that it causes repeated infections throughout life. Despite considerable efforts there is as yet no satisfactory vaccine available. This paper reviews the molecular epidemiology of the RSV and describes the complex genotypic structure of RSV epidemics. The evolution of the virus is discussed, with particular reference to the antigenic and genetic variability of the attachment glycoprotein.

Evolution of lamivudine-resistant hepatitis B virus and HIV-1 in co-infected individuals: an analysis of the CAESAR study. CAESAR co-ordinating committee

OBJECTIVES

Lamivudine has potent activity against HIV-1 and hepatitis B virus (HBV). Co-infection with these two viruses is common, and this may therefore influence the choice of antiretroviral therapies. A cohort of co-infected patients treated with lamivudine were studied in order to evaluate the differential effects of lamivudine on the two viral populations within the same individual after 44-52 weeks of therapy.

DESIGN AND METHODS

Retrospective virological analysis of an HIV-1/HBV co-infected lamivudine cohort derived from a randomized, placebo-controlled study of lamivudine in HIV infection, the CAESAR study.

RESULTS

Five of thirteen patients with HBV viral load > 10,000 copies/ml after 44-52 weeks of lamivudine therapy had genotypic drug resistance. Four of these five had a rebound of viral replication over the period of study and in one case this was associated with an alanine transaminase serum elevation. Ten of the thirteen patients had a 44-52 week HIV viral load > 1000 copies/ml, all of whom also had HIV reverse transcriptase M184V or M184I mutations.

CONCLUSIONS

Extrapolating these results to the population yields an estimated 1-year incidence of drug-resistant HBV of at least 14% in lamivudine-treated HIV-1/HBV co-infected patients. The clinical and virological benefit of HBV lamivudine monotherapy in co-infected patients should be balanced against the potential for emergence of drug resistance. Further, these data suggest that the determinants of HIV and HBV drug resistance are different and that parallel evolution, rather than co-evolution of HBV and HIV-1 in co-infected individuals occurs.

Resistance to antiviral drugs in herpes simplex virus infections among allogeneic stem cell transplant recipients: risk factors and prognostic significance

Herpes simplex virus (HSV) infections in 75 allogeneic stem cell transplant recipients were analyzed. Sixteen patients developed HSV disease following transplantation. The risk factors were age, sex (females), unrelated donor graft, and graft-versus-host disease (GVHD) grade >/=2. Seven patients did not respond to acyclovir, and 3 patients failed to respond to foscarnet. Isolates from 4 patients developed resistance to acyclovir/penciclovir, and 3 patients had foscarnet-resistant isolates. The remaining 3 patients failed to respond to acyclovir, despite having sensitive isolates. All the isolates were sensitive to cidofovir, for which the IC(50) values correlated inversely with those for acyclovir (P=.01). The risk factors for clinical resistance to antiviral drugs were a GVHD grade >/=2 (P=.001) and the lack of ganciclovir prophylaxis (P=.01), with a higher nonrelapse mortality in the latter group (P<.0001). Clinical as well as in vitro resistance to antiviral drugs is common in patients with severe GVHD and is associated with a poor outcome.

Estimation of incidence of respiratory syncytial virus infection in schoolchildren using salivary antibodies

An assay for respiratory syncytial virus (RSV)-specific IgG in saliva is described. The assay was used to examine the incidence of RSV infection in schoolchildren 7-10 years old during one RSV season. One hundred and twenty-one volunteer children provided saliva samples in October 1997 and March 1998; 18% of the children showed a fourfold or greater rise in anti-RSV IgG in the second sample. This prevalence of antibody increase is similar to that described in previous studies that measured CFT levels in serum samples. Overall, the children who showed rises in antibody levels, indicating that they had experienced an RSV infection, had lower levels of RSV-specific antibody in their preseason samples than those who showed no increase (P = 0.0018). These results show that saliva is an adequate substitute for serum in some antibody tests and may be useful for community studies. Such studies may provide surrogate markers for susceptibility to infection, which should benefit the planning of vaccination strategies.

Evaluation of the antibody specificities of human convalescent-phase sera against the attachment (G) protein of human respiratory syncytial virus: influence of strain variation and carbohydrate side chains

The C-terminal third of the attachment protein (G) of several human respiratory syncytial virus isolates was obtained as either a glycosylated protease-resistant fragment of the purified protein or a nonglycosylated GST fusion protein expressed in bacteria. The reactivity of human convalescent-phase sera with both forms of the protein segment was evaluated in immunoblots. While all serum samples reacted with the mature intact protein of the different isolates, only certain samples reacted with the nonglycosylated C-terminal segment of some viral isolates. The number of human serum samples reacting with the glycosylated C-terminal fragment was even more limited. These results highlight the heterogeneity of the human antibody response against epitopes located in the C-terminal hypervariable region of the G molecule and the influence of carbohydrate side chains for expression of these epitopes. We also have analysed the specificities of human sera by competitive enzyme-linked immunosorbent assay with murine monoclonal antibodies (MAbs). Most human serum samples inhibited virus binding of MAbs that recognised conserved or group-specific epitopes of the G protein, while only a limited fraction of those samples inhibited binding of MAbs that recognised strain-specific epitopes. These results are discussed in terms of the antibody repertoire induced after human respiratory syncytial virus infection and the relevance of escape mechanisms to preexisting antibodies for the evolution of this virus.

Analysis of hepatitis B virus quasispecies changes during emergence and reversion of lamivudine resistance in liver transplantation

This report describes nucleotide sequence analysis of part of the polymerase gene of hepatitis B virus (HBV) during the development of lamivudine-resistant HBV in five patients who received lamivudine treatment in conjunction with liver transplantation. Samples from patients were analysed before, during and after drug treatment in conjunction with serum HBV quantification by PCR. Lamivudine resistance was found to be associated with L526M and M550V changes in two patients and M550I change in three patients. Other changes associated with lamivudine resistance in some patients were V509I, A546V, S565A and A568T. The effects on HBV surface antigen are also described. Some patients were subsequently treated with famciclovir and/or ganciclovir with variable outcomes. In two out of three patients who stopped lamivudine treatment, reversion (partial or complete) to wild-type virus was observed after about 5 months. In contrast, a complex mixture of mutant viruses emerged in a third patient who stopped lamivudine treatment.

Selection of multiresistant hepatitis B virus during sequential nucleoside-analogue therapy

Hepatitis B virus (HBV) drug resistance to lamivudine is always accompanied by mutations in the viral polymerase gene at position 550, termed group 1 (M550V with L526M) or group 2 (M550I) mutations. The latter mutation has not been associated with famciclovir resistance. Thus, the addition of famciclovir to lamivudine therapy in persons with group 2 lamivudine resistance may lead to virus suppression. The effect of lamivudine/famciclovir combination therapy on HBV infection was monitored in 5 lamivudine-resistant patients by quantitative polymerase chain reaction and polymerase gene sequencing of serum virus. No patients treated with combination therapy had a decline in HBV load >1 log10. Continual evolution of the viral polymerase was detected in association with virologic resistance to both drugs. Cloning experiments identified the preexistence of these multidrug-resistant virus variants as minority species prior to addition of famciclovir therapy. HBV resistance to lamivudine monotherapy is associated with a complex mixture of variants that limit the efficacy of second-line nucleoside-analogue therapy. First-line potent combination therapy may reduce the emergence of HBV drug resistance.

Respiratory viruses in adult liver transplant recipients

BACKGROUND

The contribution of respiratory viruses to respiratory disease in adult liver transplant (LT) recipients has not been studied. We performed a prospective audit to document the incidence of respiratory syncytial viruses ([RSVs], parainfluenza virus, influenza virus, and adenovirus) after LT, and to determine their contribution to respiratory disease in this setting.

METHODS

Consecutive adult recipients were followed for 8 months after LT. Throat swabs were collected weekly for up to 12 weeks after LT, and virological surveillance was performed using conventional techniques (direct immunofluorescence and cell culture). A polymerase chain reaction assay for RSV was subsequently performed on selected specimens. Clinical data, including episodes of respiratory disease, were also recorded.

RESULTS

During the study period, 51 patients received 53 LT. Five patients died, but no viruses were isolated from these patients at any stage. A total of 323 swabs were examined by conventional techniques and yielded 35 viral isolates (10.8%). Herpes simplex virus (type 1) accounted for 33 isolates, none of which were associated with respiratory disease. Two of 323 swabs (0.62%), in 2 patients, yielded respiratory viruses (both RSV); both patients had self-limiting, mild, upper respiratory tract symptoms. In these 2 patients, the polymerase chain reaction assay was more sensitive than conventional techniques and was able to detect extended RSV excretion. Of 51 recipients, 31 (61%) were always negative for viruses. Of 51 recipients, 10 developed respiratory failure, but no respiratory viruses were isolated from any of these patients.

CONCLUSIONS

Respiratory viruses are rarely isolated from adult recipients after LT and are not associated with serious morbidity or with mortality. Routine surveillance for respiratory viruses in this patient population is not justified on the basis of this study.

Use of real-time PCR and fluorimetry to detect lamivudine resistance-associated mutations in hepatitis B virus

Very rapid amplification of DNA by PCR in small volumes can be continuously monitored by the detection of the binding of probes with a rapid cycler with built-in fluorometric detection. Primers were designed to amplify approximately 100 bp of the polymerase gene of hepatitis B virus (HBV) spanning codon 550, where mutations associated with resistance to lamivudine invariably occur. Four hybridization probes were synthesized: one was 3' labelled with fluorescein and hybridized upstream of codon 550. The others were 5' labelled with Cy5 and 3' labelled with biotin and spanned codon 550. The Cy5-labelled oligonucleotides contained either wild-type (ATG) or mutant (GTG or ATT) sequences. A Cy5-labelled probe and either the fluorescein-labelled probe or Sybr Green 1 (a compound that fluoresces when bound to double-stranded DNA) were included in each PCR. After completion of the amplification by using a LightCycler (Idaho Technology), the temperature at which the Cy5 probe melted from the product was determined in a melt program that took ca. 3 min. Pre- and posttreatment samples from eight patients (five chronic and three transplant) who failed lamivudine treatment were amplified, and the presence of mutations in codon 550 was determined by ABI sequencing and by using the LightCycler; in some cases PCR products were also cloned, and multiple clones were sequenced. Concordant results were obtained in all cases. We found the LightCycler to be better at resolving the sequences of genomic mixtures; for example, two samples showed a sequence at codon 550 of (A/G)T(G/T), which was found by fluorimetry to be mixtures of GTG and ATT but no ATG, and this finding was confirmed by the sequencing of clones. However, this approach was not more sensitive than population sequencing for the detection of the presence of mixtures. Overall, this pilot study has demonstrated an approach that could be an extremely rapid and economical method for the detection of lamivudine resistance-associated mutations in HBV.

Molecular epidemiology of respiratory syncytial virus in The Gambia

Respiratory syncytial virus (RSV) infection in The Gambia occurs seasonally in association with the rainy season. This study examined the genetic variability of RSV isolates from four consecutive epidemics from 1993-6. Each epidemic was made up of a number of variants which were replaced in subsequent epidemics. Analysis of attachment (G) protein gene sequences showed that isolates were closely related to those observed in the rest of the world. However, many isolates from 1993 and 1994 were unlike other isolates observed in the developed world during this period and were more similar to isolates from 1984 in Europe. In addition, the most commonly observed genotype in the UK in the 1990s was not detected in The Gambia during this period.