ABSTRACT Human immunodeficiency virus type 1 (HIV-1) can evade immunity shortly after transmission to a new host but the clinical significance of this early viral adaptation in HIV infection is not clear. We present an analysis of sequence variation from a longitudinal cohort study of HIV adaptation in 189 acute seroconverters followed for up to 3 years. We measured the rates of variation within well-defined epitopes to determine associations with the HLA-linked hazard of disease progression. We found early reversion across both the gag and pol genes, with a 10-fold faster rate of escape in gag (2.2 versus 0.27 forward mutations/1,000 amino acid sites). For most epitopes (23/34), variation in the HLA-matched and HLA-unmatched controls was similar. For a minority of epitopes (8/34, and generally associated with HLA class I alleles that confer clinical benefit), new variants appeared early and consistently over the first 3 years of infection. Reversion occurred early at a rate which was HLA-dependent and correlated with the HLA class 1-associated relative hazard of disease progression and death (P = 0.0008), reinforcing the association between strong cytotoxic T-lymphocyte responses, viral fitness, and disease status. These data provide a comprehensive overview of viral adaptation in the first 3 years of infection. Our findings of HLA-dependent reversion suggest that costs are borne by some escape variants which may benefit the host, a finding contrary to a simple immune evasion paradigm. These epitopes, which are both strongly and frequently recognized, and for which escape involves a high cost to the virus, have the potential to optimize vaccine design.

Early anti-retroviral treatment (ART) in primary human immunodeficiency virus (HIV) infection (PHI) may have unique, restorative immunological and virological benefits which could enhance clinical outcomes. However, the sustainability of these HIV-specific immune responses and their impact on clinical outcome remains unclear. We present a 3-year longitudinal clinical and immunological follow-up of a single-arm, prospective study assessing the long-term impact of a short-course of ART (SCART) during PHI. Twenty-eight subjects with defined PHI received 3 months of SCART at HIV-1 seroconversion. HIV-specific interferon-gamma(+) CD4(+) T cell responses, CD4 cell counts and plasma viral loads were assessed prospectively. Clinical outcome was defined as the time taken from PHI to a fall in CD4 cell counts < 350 cells/mu l on two or more occasions. Of 28 patients, 25 (89%) had detectable HIV-specific CD4(+) helper responses at baseline. Five of 11 (45%) patients had preserved HIV-specific CD4(+) responses 3 years after stopping SCART. Neither the presence nor magnitude of HIV-1-specific T helper responses either at baseline or 3 years following SCART cessation predicted clinical outcome. Rebound viraemia associated with stopping SCART did not diminish HIV-1-specific CD4(+) responses. Long-term (> 3 years) preservation of virus-specific CD4(+) cells occurred in 45% of patients receiving SCART in PHI. There was no correlation between either the presence or magnitude of these responses and clinical outcome.

Human cytomegalovirus (HCMV) remains an important cause of morbidity after allotransplantation, causing a range of direct effects including hepatitis, pneumonitis, enteritis and retinitis. A dominant risk factor for HCMV disease is high level viral replication in blood but it remains unexplained why only a subset of patients develop such diseases. In this detailed study of 25 renal transplant recipients, we show that functional impairment of HCMV specific CD8 T cells in the production of interferon gamma was associated with a 14-fold increased risk of progression to high level replication. The CD8 T-cell impairment persisted during the period of high level replication and was more prominent in patients above 40 years of age (odds ratio = 1.37, p = 0.01) and was also evident in dialysis patients. Threshold levels of functional impairment were associated with an increased risk of future HCMV replication and there was a direct relationship between the functional capacity of HCMV ppUL83 CD8 T cells and HCMV load (R(2)= 0.83). These results help to explain why a subset of seropositive individuals develop HCMV replication and are at risk of end-organ disease and may facilitate the early identification of individuals who would benefit from targeted anti-HCMV therapy after renal transplantation.

ABSTRACT The possession of some HLA class I molecules is associated with delayed progression to AIDS. The mechanism behind this beneficial effect is unclear. We tested the idea that cytotoxic T-cell responses restricted by advantageous HLA class I molecules impose stronger selection pressures than those restricted by other HLA class I alleles. As a measure of the selection pressure imposed by HLA class I alleles, we determined the extent of HLA class I-associated epitope variation in a cohort of European human immunodeficiency virus (HIV)-positive individuals ( n = 84). We validated our findings in a second, distinct cohort of African patients ( n = 516). We found that key HIV epitopes restricted by advantageous HLA molecules (B27, B57, and B51 in European patients and B5703, B5801, and B8101 in African patients) were more frequently mutated in individuals bearing the restricting HLA than in those who lacked the restricting HLA class I molecule. HLA alleles associated with clinical benefit restricted certain epitopes for which the consensus peptides were frequently recognized by the immune response despite the circulating virus's being highly polymorphic. We found a significant inverse correlation between the HLA-associated hazard of disease progression and the mean HLA-associated prevalence of mutations within epitopes ( P = 0.028; R 2 = 0.34). We conclude that beneficial HLA class I alleles impose strong selection at key epitopes. This is revealed by the frequent association between effective T-cell responses and circulating viral escape mutants and the rarity of these variants in patients who lack these favorable HLA class I molecules, suggesting a significant pressure to revert.

Human immunodeficiency virus type 1 (HIV-1) genetic diversity is a major obstacle for the design of a successful vaccine. Certain viral polymorphisms encode human leukocyte antigen (HLA)-associated immune escape, potentially overcoming limited vaccine protection. Although transmission of immune escape variants has been reported, the overall extent to which this phenomenon occurs in populations and the degree to which it contributes to HIV-1 viral evolution are unknown. Selection on the HIV-1 env gene at transmission favors neutralization-sensitive variants, but it is not known to what degree selection acts on the internal HIV-1 proteins to restrict or enhance the transmission of immune escape variants. Studies have suggested that HLA class I may determine susceptibility to HIV-1 infection, but a definitive role for HLA at transmission remains unproven. Comparing populations of acute seroconverters and chronically infected patients, we found no evidence of selection acting to restrict transmission of HIV-1 variants. We found that statistical associations previously reported in chronic infection between viral polymorphisms and HLA class I alleles are not present in acute infection, suggesting that the majority of viral polymorphisms in these patients are the result of transmission rather than de novo adaptation. Using four episodes of HIV-1 transmission in which the donors and recipients were both sampled very close to the time of infection we found that, despite a transmission bottleneck, genetic variants of HIV-1 infection are transmitted in a frequency-dependent manner. As HIV-1 infections are seeded by unique donor-adapted viral variants, each episode is a highly individual antigenic challenge. Host-specific, idiosyncratic HIV-1 antigenic diversity will seriously tax the efficacy of immunization based on consensus sequences.

The evolution of the human immunodeficiency virus (HIV-1) during chronic infection involves the rapid, continuous turnover of genetic diversity. However, the role of natural selection, relative to random genetic drift, in governing this process is unclear. We tested a stochastic model of genetic drift using partial envelope sequences sampled longitudinally in 28 infected children. In each case the Bayesian posterior (empirical) distribution of coalescent genealogies was estimated using Markov chain Monte Carlo methods. Posterior predictive simulation was then used to generate a null distribution of genealogies assuming neutrality, with the null and empirical distributions compared using four genealogy-based summary statistics sensitive to nonneutral evolution. Because both null and empirical distributions were generated within a coalescent framework, we were able to explicitly account for the confounding influence of demography. From the distribution of corrected P-values across patients, we conclude that empirical genealogies are more asymmetric than expected if evolution is driven by mutation and genetic drift only, with an excess of low-frequency polymorphisms in the population. This indicates that although drift may still play an important role, natural selection has a strong influence on the evolution of HIV-1 envelope. A negative relationship between effective population size and substitution rate indicates that as the efficacy of selection increases, a smaller proportion of mutations approach fixation in the population. This suggests the presence of deleterious mutations. We therefore conclude that intrahost HIV-1 evolution in envelope is dominated by purifying selection against low-frequency deleterious mutations that do not reach fixation.

OBJECTIVE--To test the effect of interferon alfa and tribavirin (ribavirin) in patients with rabies encephalitis. DESIGN--An open trial of chemotherapy and intensive care in patients with early rabies. SETTING--The intensive care unit of a Bangkok hospital. PATIENTS--Four conscious men with clinical rabies encephalitis. INTERVENTIONS--Rapid virological diagnosis of rabies. Treatment with intravenous and intraventricular injections of high doses of lymphoblastoid interferon alfa in three patients and tribavirin in one patient. Intensive care was given throughout. MAIN OUTCOME MEASURES--Rabies infection confirmed by antigen detection and virus isolation. Rabies neutralising antibody and specific IgM sought in serum and cerebrospinal fluid. Interferon concentrations monitored before and during treatment in three patients. RESULTS--Interferon alfa treatment produced high concentrations in serum and cerebrospinal fluid. All four patients died after 5 1/2 to 12 1/2 days of treatment with no evidence of virostatic or clinically beneficial effects from either treatment. CONCLUSION--Interferon alfa treatment is not effective in rabies encephalitis. The use of tribavirin warrants further study, possibly combined with new therapeutic methods.

Quinine dihydrochloride was given intravenously to 12 women with severe falciparum malaria in the third trimester of pregnancy. The initial dose consisted of 10 or 20 mg salt/kg over 4 h and was followed by 10 mg salt/kg every 8 h until patients were fit to swallow, when quinine sulphate tablets were given. Uterine activity showed little or no change despite rising quinine concentrations. Of 3 patients in labour, 2 proceeded normally while a third had a successful caesarean section for fetal distress. Late (type II) decelerations of the fetal heart rate were recorded in 6 patients before treatment but in most patients signs of fetal distress diminished as the maternal temperature fell. Hypoglycaemia and hyperinsulinaemia developed in 7 patients, in 2 before quinine was started. The important toxic effect of quinine in late pregnancy is not an oxytocic action but rather its capacity to release insulin.

SMS 201-995, a new long-acting, synthetic somatostatin analogue, dose 50 μg/h, given as a continuous intravenous infusion, completely abolished quinine-induced insulin release in 9 healthy Thai volunteers. Hyperinsulinaemia, which caused sustained hypoglycaemia in a 32-year-old post-partum Thai patient who was receiving intravenous quinine for falciparum malaria, was suppressed within 30 min of starting SMS 201-995, and the patient became fully conscious. This octapeptide antagonises the stimulatory effect of quinine on the pancreatic beta cell and is a specific therapy for life-threatening hyperinsulinaemic hypoglycaemia complicating falciparum malaria.

Both neutralising antibody and interferon play a part in protection of animals against death from rabies virus infection. Interferon induction was therefore sought in 53 volunteers within 24 hours of receiving human diploid cell strain vaccine or fetal bovine kidney cell vaccine given either intramuscularly or intradermally. Repeat observations were made in 18 subjects following a second dose of vaccine seven days later. No interferon was detected in any sample tested although no subject had any detectable rabies neutralising antibody on day 0. The sensitivity of the interferon assay, and comparison with other studies are discussed. An interferon inducer suitable for human use should be sought as an alternative to, or a replacement for, passive rabies immunization.