Frank E. Brewster

X-linked lymphoproliferative syndrome. Natural history of the immunodeficiency.

The X-linked lymphoproliferative syndrome is characterized by immunodeficiency to Epstein-Barr virus (EBV) manifested by severe or fatal infectious mononucleosis and acquired immunodeficiency. We studied immune responses in six males of a well-characterized kindred with the X-linked lymphoproliferative syndrome. Two males were studied before and during acute fatal EBV infection. Both individuals demonstrated normal cellular and humoral immunity before EBV infection. During acute EBV infection, both individuals developed vigorous cytotoxic cellular responses against EBV-infected and -uninfected target cells. Anomalous killer and natural killer T cell activity was demonstrated against a variety of lymphoid cell lines, autologous fibroblasts and autologous hepatocytes. Effector cells responsible for anomalous killing reacted with a pan-T cell monoclonal antibody, and belonged to the OKT.8 T cell subset. Death in each case was caused by liver failure, but one patient developed extensive liver necrosis, whereas the other developed a massive infiltration of the liver with EBV-infected immunoblasts after aggressive immunosuppressive therapy. Immunological studies were performed on four males who had survived EBV infection years previously. They demonstrated global cellular immune defects with deficiencies of lymphocyte proliferative responses to mitogens and antigens, humoral immune deficiencies, abnormalities of regulatory T cell subsets and deficient natural killer cell activity. We propose that an aberrant immune response triggered by acute EBV infection results in unregulated anomalous killer and natural killer cell activity against EBV infected and uninfected cells. These studies suggest that global immune defects appearing in males with X-linked lymphoproliferative syndrome who survive EBV infection are epiphenomenon.

Hemophiliac immunodeficiency: Influence of exposure to factor VIII concentrate, LAV/HTLV-III, and herpesviruses

The relationship between hemophiliac immunodeficiency and exposures to factor VIII concentrate, LAV/HTLV-III retrovirus, and infection with Epstein-Barr virus and cytomegalovirus was examined. Exposure to factor VIII concentrate was significantly correlated with decreased percentages of T helper/inducer cells, decreased T helper/suppressor cell ratios, and decreased proliferative responses to plant mitogens. LAV/HTLV-III seropositivity was the primary predictor of increased percentages of HLA-DR-bearing mononuclear cells and decreased proliferative responses to pokeweed mitogen. Epstein-Barr virus and cytomegalovirus infections acted in a synergistic manner with LAV/HTLV-III to produce immunoregulatory defects. Increased percentages of T suppressor cells and decreased delayed cutaneous hypersensitivity skin test responses were observed in LAV/HTLV-III seropositive hemophiliacs infected with Epstein-Barr or cytomegalovirus. We conclude that hemophiliacs receiving commercial factor VIII concentrate experience several stepwise incremental insults to the immune system: alloantigens in factor VIII concentrate, LAV/HTLV-III infections, and herpesvirus infections.

Treatment of life-threatening Epstein-Barr virus infections with acyclovir☆

Two pediatric patients with life-threatening Epstein-Barr virus infections were studied immunologically and treated with acyclovir [9-(2-hydroxyethoxymethyl) guanine]. The patient with chronic active Epstein-Barr virus infection who experienced massive hepatosplenomegaly, pancytopenia, and failure to thrive demonstrated abnormalities of T and B lymphocytes. A second patient, with the X-linked lymphoproliferative syndrome, experienced a rapidly fatal course of acute Epstein-Barr virus infection which typifies this yet undefined immunodeficiency to Epstein-Barr virus. In each case, objective evidence for clinical improvement or antiviral effect of acyclovir treatment was not apparent. Abnormally productive Epstein-Barr virus infections did not appear to play a major role in the clinical syndromes observed. Current studies are focused on treatment of immunologically normal patients with early complicated Epstein-Barr virus infection.

Genotypic and functional properties of early infant HIV-1 envelopes

BackgroundUnderstanding the properties of HIV-1 variants that are transmitted from women to their infants is crucial to improving strategies to prevent transmission. In this study, 162 full-length envelope (env) clones were generated from plasma RNA obtained from 5 HIV-1 Clade B infected mother-infant pairs. Following extensive genotypic and phylogenetic analyses, 35 representative clones were selected for functional studies.ResultsInfant quasispecies were highly homogeneous and generally represented minor maternal variants, consistent with transmission across a selective bottleneck. Infant clones did not differ from the maternal in env length, or glycosylation. All infant variants utilized the CCR5 co-receptor, but were not macrophage tropic. Relatively high levels (IC50 ≥ 100 μg/ml) of autologous maternal plasma IgG were required to neutralize maternal and infant viruses; however, all infant viruses were neutralized by pooled sera from HIV-1 infected individuals, implying that they were not inherently neutralization-resistant. All infant viruses were sensitive to the HIV-1 entry inhibitors Enfuvirtide and soluble CD4; none were resistant to Maraviroc. Sensitivity to human monoclonal antibodies 4E10, 2F5, b12 and 2G12 varied.ConclusionsThis study provides extensive characterization of the genotypic and functional properties of HIV-1 env shortly after transmission. We present the first detailed comparisons of the macrophage tropism of infant and maternal env variants and their sensitivity to Maraviroc, the only CCR5 antagonist approved for therapeutic use. These findings may have implications for improving approaches to prevent mother-to-child HIV-1 transmission.

Nevirapine synergistically inhibits HIV-1 replication in combination with zidovudine, interferon or CD4 immunoadhesin

Objective:To determine whether synergistic inhibition of HIV-1 replication would result from the in vitro use of nevirapine in combination with zidovudine, interferon (IFN)-α 2C, and CD4 immunoadhesin. Design and methods:The non-nucleoside reverse transcriptase inhibitor nevirapine (formerly BI-RG-587) was tested in combination with the other antiretroviral agents. Assays were performed on stimulated peripheral blood lymphocytes infected with HIV-1. Virus replication was assessed by the release of viral p24 antigen into culture supernatants. The median-effect principle was used to assess for synergistic interactions of the combined agents. Results:Zidovudine, IFN-α 2C and CD4 immunoadhesin, when used in combination with nevirapine, synergistically inhibited HIV-1 replication in human peripheral blood lymphocytes compared with each agent used alone. Some analyses were also consistent with additive effects, but antagonism was not noted. Conclusion:These in vitro findings provide a scientific basis for future trials with similar drug combinations.

Delayed cutaneous hypersensitivity reactions in hemophiliac subjects treated with factor concentrate

Cutaneous delayed-type hypersensitivity was measured using the Multitest CMI in a group of 97 patients with hemophilia who were enrolled in the New England Area Comprehensive Clinic. The Multitest CMI is a multipuncture system that dispenses seven test antigens including tetanus, diphtheria, Streptococcus, Proteus, tuberculin, Candida, and Trichophyton, and a glycerine-saline control solution. A reaction was considered positive if there was induration of at least 2 mm. If the results of one or more skin tests were positive, the patient was considered to have a positive reaction. Of the 83 patients with severe or moderate hemophilia A, 51 percent had negative reactions. No study control subject and only one patient with hemophilia B had a negative reaction. The 42 patients with hemophilia A who showed no reaction used a significantly greater amount of factor VIII concentrate than did those with hemophilia A who responded positively (1,960 units/kg per year versus 1,360 units/kg per year; p less than 0.025) and included a higher percent of patients who had seropositive results for human T lymphotropic virus type III (HTLV-III) antibody (89 percent versus 69 percent, p less than 0.025).

Isolation of human immunodeficiency virus from hemophiliacs: Correlation with clinical symptoms and immunologic abnormalities

As part of a prospective study of human immunodeficiency virus (HIV) infection in hemophilia, peripheral blood mononuclear cells (PBMs) from 72 individuals without acquired immune deficiency syndrome (AIDS) or AIDS-related complex (ARC) were cultured for virus. HIV was isolated from PBMs from 16 (24%) of 66 patients with hemophilia who were seropositive for HIV and from none of six seronegative patients. Cells from five of six patients from which HIV was isolated were again successfully cultured for virus 3 to 12 months later. HIV core P24 antigen was detected in serum from seven of 15 patients with HIV-positive cells and from eight of 50 with HIV-negative cells. Patients with hemophilia with isolation-positive cells had significantly fewer T helper cells and significantly lower T helper/T suppressor ratios, pokeweed mitogen responsiveness, and total platelet counts than did those whose cells did not yield HIV on cultivation. HIV neutralizing antibody titers did not differ between hemophiliacs with or without HIV-positive PBMs. Three of the 16 patients with virus-positive cells developed AIDS, and two ARC, within 18 months of the study, compared with three of 50 seropositive hemophiliacs whose cells did not yield virus, who developed ARC during the same period. The significant decrease in the number of T helper cells, decreased platelet counts, and higher rate of progression to AIDS in the group with HIV isolation may reflect a heavier virus load, indicating that the ability to culture HIV may be an early marker of more significant disease.

Identification and Characterization of HIV-1 CD8+ T Cell Escape Variants with Impaired Fitness

In this study, amino acid sequence variation in human immunodeficiency virus (HIV)-1 Gag CD8(+) T cell epitopes was examined in untreated mother-infant pairs. Several HIV-1 CD8(+) T cell escape variants were identified within maternal plasma viral p17 and p24 sequences that were either not detected or did not persist in the plasma of their non-HLA-matched HIV-1-infected infants. Viruses constructed with each of these mutations demonstrated reduced viral replication in vitro and reduced expression of p17 and p24 proteins compared with wild type. Reduced recognition of the variant sequences compared with wild-type sequence was also demonstrated by enzyme-linked immunospot assays. Nontransmission or reversion after transmission was thus associated with reduced viral fitness cost in vivo. Better understanding of the balance between CD8(+) T cell selective pressures and viral fitness cost may facilitate the identification of optimal viral sequences for inclusion in HIV-1 vaccines.

Epstein-Barr Virus Latent Membrane Protein 1 Genetic Variability in Peripheral Blood B Cells and Oropharyngeal Fluids

ABSTRACT We report the diversity of latent membrane protein 1 (LMP1) gene founder sequences and the level of Epstein-Barr virus (EBV) genome variability over time and across anatomic compartments by using virus genomes amplified directly from oropharyngeal wash specimens and peripheral blood B cells during acute infection and convalescence. The intrahost nucleotide variability of the founder virus was 0.02% across the region sequences, and diversity increased significantly over time in the oropharyngeal compartment (P = 0.004). The LMP1 region showing the greatest level of variability in both compartments, and over time, was concentrated within the functional carboxyl-terminal activating regions 2 and 3 (CTAR2 and CTAR3). Interestingly, a deletion in a proline-rich repeat region (amino acids 274 to 289) of EBV commonly reported in EBV sequenced from cancer specimens was not observed in acute infectious mononucleosis (AIM) patients. Taken together, these data highlight the diversity in circulating EBV genomes and its potential importance in disease pathogenesis and vaccine design. IMPORTANCE This study is among the first to leverage an improved high-throughput deep-sequencing methodology to investigate directly from patient samples the degree of diversity in Epstein-Barr virus (EBV) populations and the extent to which viral genome diversity develops over time in the infected host. Significant variability of circulating EBV latent membrane protein 1 (LMP1) gene sequences was observed between cellular and oral wash samples, and this variability increased over time in oral wash samples. The significance of EBV genetic diversity in transmission and disease pathogenesis are discussed.

Pilot study on the immunogenicity of paired Env immunogens from mother-to-child transmitted HIV-1 isolates

Recent studies have reported that founder viruses play unique roles in establishing HIV-1 infection. Understanding the biological and immunological features of envelope glycoproteins (Env) from such viruses may facilitate the development of effective vaccines against HIV-1. In this report, we evaluated the immunogenicity of gp120 immunogens from two pairs of clade B and two pairs of clade C mother-to-child transmitted (MTCT) HIV-1 variants that had various levels of sensitivity to broadly neutralizing monoclonal antibodies. Individual gp120 DNA and protein vaccines were produced from each of the eight MTCT Env antigens included in the current study. Rabbits were immunized with these gp120 immunogens by the DNA prime-protein boost approach. High level Env-specific antibody responses were elicited by all MTCT gp120 immunogens. However, their abilities to elicit neutralizing antibody (NAb) responses differed and those from relatively neutralization-resistant variants tended to be more effective in eliciting broader NAb. Results of this pilot study indicated that not all MTCT Env proteins have the same potential to elicit NAb. Understanding the mechanism(s) behind such variation may provide useful information in formulating the next generation of HIV vaccines.