Daniel M. Chafets

High-level long-term white blood cell microchimerism after transfusion of leukoreduced blood components to patients resuscitated after severe traumatic injury

BACKGROUND: Long‐term white blood cell (WBC) microchimerism (MC), of at least 2 years, has been reported in trauma patients receiving fresh nonleukoreduced (non‐LR) blood. It is unknown, however, whether this occurs with LR blood products that are nearly devoid of WBCs. Twenty‐seven patients transfused with LR and non‐LR blood products were studied after severe traumatic injury. A secondary aim was to explore donor‐recipient mixed lymphocyte reactivity in vitro.

A Prospective Study of Sexual Transmission of Human T Lymphotropic Virus (HTLV)–I and HTLV-II

BACKGROUND Cross-sectional studies support sexual transmission of human T lymphotropic virus (HTLV)-I/II; however, prospective incidence data, particularly for HTLV-II, are limited. METHODS A cohort of 85 HTLV-positive (30 with HTLV-I and 55 with HTLV-II) blood donors and their stable (>or=6 months) heterosexual sex partners were followed biannually over the course of a 10-year period. RESULTS Four of 85 initially seronegative sex partners of HTLV-I and -II carriers seroconverted, for an incidence rate (IR) of 0.6 transmissions/100 person-years (py) (95% confidence interval [CI], 0.2-1.6). This includes 2 HTLV-I transmissions/219 py (IR, 0.9 transmissions/100 py [95% CI, 0.1-3.3]) and 2 HTLV-II transmissions/411 py (IR, 0.5 transmissions/100 py [95% CI, 0.06-1.8]), with no significant difference by HTLV type. There were 2 male-to-female (IR, 1.2 transmissions/100 py [95% CI, 0.1-4.3]) and 2 female-to-male (IR, 0.4 transmissions/100 py [95% CI, 0.05-1.6) transmissions. HTLV-I or -II proviral load was 2 log10 lower in newly infected partners than in index positive partners who transmitted HTLV (P=.007). CONCLUSIONS The incidence of sexual transmission of HTLV-II may be similar to that of HTLV-I, and female-to-male transmission may play a more important role than previously thought. HTLV-I and -II proviral load may be lower in sexually acquired infection, because of a small infectious dose.

Enhanced ascertainment of microchimerism with real-time quantitative polymerase chain reaction amplification of insertion-deletion polymorphisms

BACKGROUND: The characterization of microchimerism (MC) by gene amplification has been limited by few allogeneic markers, ascertainment bias, and assay analytic performance. To address this, a panel of 12 MC assays based on insertion‐deletion (InDel) polymorphisms had been optimized.

Higher Human T Lymphotropic Virus (HTLV) Provirus Load Is Associated with HTLV-I versus HTLV-II, with HTLV-II Subtype A versus B, and with Male Sex and a History of Blood Transfusion

BACKGROUND High human T lymphotropic virus (HTLV)-I provirus load (VL) has been associated with an increased risk of HTLV-associated myelopathy, but little is known about variation in HTLV-I or -II VLs by demographic characteristics and risk behaviors. METHODS We measured HTLV-I and HTLV-II VLs in a large cohort of 127 HTLV-I-seropositive and 328 HTLV-II-seropositive former blood donors, by use of real-time polymerase chain reaction using tax primers. Multivariable linear regression was used to control for confounding by relevant covariates. RESULTS The mean VLs were 3.28 log(10) copies/10(6) peripheral blood mononuclear cells (PBMCs) (range, 0.5-5.3 log(10) copies/10(6) PBMCs) for HTLV-I and 2.60 log(10) copies/10(6) PBMCs (range, 0.05-5.95 log(10) copies/10(6) PBMCs) for HTLV-II (P<.0001). HTLV-II VLs were higher in those subjects with subtype A infection (mean, 2.82 log(10) copies/10(6) PBMCs) than in those with subtype B infection (mean, 2.29 log(10) copies/10(6) PBMCs) (P=.005). Higher HTLV-I VL was associated with previous receipt of a blood transfusion (P=.04), and lower HTLV-II VL was associated with female sex (P=.007). These associations persisted in virus-specific multivariate linear regression models controlling for potential confounding variables. CONCLUSIONS VL was significantly higher in HTLV-I than in HTLV-II infection and was higher in HTLV-II subtype A than in HTLV-II subtype B infection. Chronic HTLV VLs may be related to the infectious dose acquired at the time of infection, with higher VLs following acquisition by blood transfusion and lower VLs following sexual acquisition.

Long-Term Variations in Human T Lymphotropic Virus (HTLV)–I and HTLV-II Proviral Loads and Association with Clinical Data

BACKGROUND The human T lymphotropic virus (HTLV)-I or -II proviral load (VL) may be linked to viral pathogenesis, but prospective data on VL and disease outcomes are lacking. METHODS Using data from a prospective cohort study of HTLV disease outcomes, we examined baseline VLs with real-time quantitative polymerase chain reaction in 122 HTLV-I- and 319 HTLV-II-infected subjects and serial VLs over the course of 6 visits in a subset of 30 HTLV-I- and 30 HTLV-II-infected subjects. Cox and logistic-regression models were used to test baseline associations, and repeated-measures analysis was used to study variations in VL over time. RESULTS Over the course of a median of 10.4 years, HTLV-I VLs decreased slightly (slope, -0.017 log(10) copies/10(6) peripheral blood mononuclear cells [PBMCs]/year; P=.042) and HTLV-II VLs did not change (slope, -0.019 log(10) copies/10(6) PBMCs/year; P=.165). Changes in VL over time were associated positively with alcohol use (P=.07) and negatively with black race (P=.03) for HTLV-I and positively with smoking (P=.08) for HTLV-II. In the larger group, there was no association between baseline VL and disease outcomes. In the smaller group with serial VL data, there was an association between increasing VL and bladder or kidney infections for both HTLV-I (P=.005) and HTLV-II (P=.022). CONCLUSIONS HTLV VLs are stable over time, but alcohol and tobacco intake may affect the progression of VLs. The association between increasing VLs and bladder/kidney infection may be explained by early HTLV-related neuropathologic progression.

Development of a real-time polymerase chain reaction assay for sensitive detection and quantitation of Babesia microti infection

Babesia microti, the most frequently implicated pathogen in transfusion‐transmitted babesiosis, is widely endemic in the Northeast and upper Midwestern United States. High seroprevalence in endemic areas limits antibody‐based donor screening. A high‐performance molecular test is needed to identify donors in the preseroconversion window phase as well as to discriminate past serologic exposure with parasite clearance from continued parasitemia.

Microchimerism decades after transfusion among combat-injured US veterans from the Vietnam, Korean, and World War II conflicts.

BACKGROUND: Blood transfusion after traumatic injury can result in microchimerism (MC) of donor white cells (WBCs) in the recipient as late as 2 to 3 years postinjury, the longest prospective follow‐up to date. The purpose of this study was to determine how long transfusion‐associated MC lasts after traumatic injury.

Manufacturing method affects mitochondrial DNA release and extracellular vesicle composition in stored red blood cells

Damage‐associated molecular patterns (DAMPs) are found in transfusion products, but their potential impacts are not fully understood. We examined the influence of manufacturing method on levels of mitochondrial (mt) DNA and extracellular vesicle (EV) DAMPs in red cell concentrates (RCCs).

Neutralizing Monoclonal Antibodies Block Chikungunya Virus Entry and Release by Targeting an Epitope Critical to Viral Pathogenesis

We evaluated the mechanism by which neutralizing human monoclonal antibodies inhibit chikungunya virus (CHIKV) infection. Potently neutralizing antibodies (NAbs) blocked infection at multiple steps of the virus life cycle, including entry and release. Cryo-electron microscopy structures of Fab fragments of two human NAbs and chikungunya virus-like particles showed a binding footprint that spanned independent domains on neighboring E2 subunits within one viral spike, suggesting a mechanism for inhibiting low-pH-dependent membrane fusion. Detailed epitope mapping identified amino acid E2-W64 as a critical interaction residue. An escape mutation (E2-W64G) at this residue rendered CHIKV attenuated in mice. Consistent with these data, CHIKV-E2-W64G failed to emerge in vivo under the selection pressure of one of the NAbs, IM-CKV063. As our study suggests that antibodies engaging the residue E2-W64 can potently inhibit CHIKV at multiple stages of infection, antibody-based therapies or immunogens that target this region might have protective value.

Development of a mitochondrial DNA real-time polymerase chain reaction assay for quality control of pathogen reduction with riboflavin and ultraviolet light

Transfusion is associated with a risk of infection and alloimmunization. Pathogen reduction using riboflavin and UV light (Mirasol treatment) inactivates pathogens and leucocytes. With increasing adoption of the technology in clinical use, regulatory agencies have recommended the introduction of quality control measures to monitor pathogen reduction efficacy. We sought to develop a real‐time PCR‐based assay to document the impact of pathogen reduction on the mitochondrial genome in blood components.