Sonia Bakkour

Zika Virus Tissue and Blood Compartmentalization in Acute Infection of Rhesus Macaques.

Animal models of Zika virus (ZIKV) are needed to better understand tropism and pathogenesis and to test candidate vaccines and therapies to curtail the pandemic. Humans and rhesus macaques possess similar fetal development and placental biology that is not shared between humans and rodents. We inoculated 2 non-pregnant rhesus macaques with a 2015 Brazilian ZIKV strain. Consistent with most human infections, the animals experienced no clinical disease but developed short-lived plasma viremias that cleared as neutralizing antibody developed. In 1 animal, viral RNA (vRNA) could be detected longer in whole blood than in plasma. Despite no major histopathologic changes, many adult tissues contained vRNA 14 days post-infection with highest levels in hemolymphatic tissues. These observations warrant further studies to investigate ZIKV persistence and its potential clinical implications for transmission via blood products or tissue and organ transplants.

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).

First Zika-positive donations in the continental United States

Zika virus (ZIKV) has spread in the Americas, including parts of the southern United States, and infection can be associated with serious complications, including congenital brain abnormalities. Probable transfusion transmission of ZIKV has been documented in Brazil.

Relative analytical sensitivity of donor nucleic acid amplification technology screening and diagnostic real-time polymerase chain reaction assays for detection of Zika virus RNA

Zika virus (ZIKV) has spread rapidly in the Pacific and throughout the Americas and is associated with severe congenital and adult neurologic outcomes. Nucleic acid amplification technology (NAT) assays were developed for diagnostic applications and for blood donor screening on high‐throughput NAT systems. We distributed blinded panels to compare the analytical performance of blood screening relative to diagnostic NAT assays.

First cases of Zika virus–infected US blood donors outside states with areas of active transmission

Zika virus (ZIKV) is transmitted by Aedes mosquitos and can result in severe congenital and adult neurologic abnormalities. ZIKV has rapidly spread northward through Central America and the Caribbean and autochthonous cases have been identified in the continental United States. High rates of ZIKA RNA positivity were detected in blood donors during previous epidemics. ZIKV transmission by transfused blood from healthy donor components has been a growing concern.

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.

Assessment of nucleic acid modification induced by amotosalen and ultraviolet A light treatment of platelets and plasma using real-time polymerase chain reaction amplification of variable length fragments of mitochondrial DNA

Pathogen inactivation methods are increasingly used to reduce the risk of infections after transfusion of blood products. Photochemical treatment (PCT) of platelets (PLTs) and plasma with amotosalen and ultraviolet A (UVA) light inactivates pathogens and white blood cells through formation of adducts between amotosalen and nucleic acid that block replication, transcription, and translation. The same adducts block the amplification of nucleic acids using polymerase chain reaction (PCR) in a manner that correlates with the number of adducts formed, providing a direct quality control (QC). Current QC measures for PCT rely on indirect methods that measure the delivered UVA dose or percent residual amotosalen after illumination, rather than directly measuring nucleic acid modification.

Analysis of maternal microchimerism in rhesus monkeys (Macaca mulatta) using real-time quantitative PCR amplification of MHC polymorphisms.

Although pregnancy-associated microchimerism is known to exist in humans, its clinical significance remains unclear. Fetal microchimerism has been documented in rhesus monkeys, but the trafficking and persistence of maternal cells in the monkey fetus and infant have not been fully explored. To investigate the frequency of maternal microchimerism in the rhesus monkey (Macaca mulatta), a real-time polymerase chain reaction (PCR) strategy was developed and validated to target polymorphic major histocompatibility complex (MHC) gene sequences. Informative PCR assays were identified for 19 of 25 dams and their respective offspring. Analyses were performed on tissues (thymus, liver, spleen, lymph nodes, and bone marrow) and peripheral blood mononuclear cells (PBMCs) collected prenatally and postnatally in a subset of animals. Seven of 19 monkeys had detectable maternal microchimerism in at least one compartment (range: 0.001–1.9% chimeric cells). In tissues, maternal microchimerism was found in 2 of 7 fetuses and 3 of 12 juveniles (1–1.5 years of age), and most of the animals that were positive had microchimeric cells in more than one tissue. Maternal microchimerism was detected in PBMCs from all (4 of 4) fetuses. These observations suggest that maternal microchimerism occurs in the rhesus monkey fetus and can be detected in tissues in a subset of offspring after birth.

p38 mitogen-activated protein kinase regulates mitochondrial function and microvesicle release in riboflavin- and ultraviolet light–treated apheresis platelet concentrates

Biochemical analyses of mechanisms triggered in platelets (PLTs) upon pathogen inactivation (PI) are crucial to further understand the impact of PI on PLT functionality and, subsequently, quality.