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Ahmed, Asim

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Ahmed

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Asim

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Ahmed, Asim
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    Fatal Eastern Equine Encephalitis in a Patient on Maintenance Rituximab: A Case Report
    (Oxford University Press, 2017) Solomon, Isaac H.; Ciarlini, Pedro D. S. C.; Santagata, Sandro; Ahmed, Asim; De Girolami, Umberto; Prasad, Sashank; Mukerji, Shibani
    Abstract A 63-year-old woman on rituximab maintenance for follicular lymphoma presented with headaches, vomiting, and fever, and was diagnosed with eastern equine encephalomyelitis by cerebrospinal fluid polymerase chain reaction. Eastern equine encephalomyelitis immunoglobulin (Ig)G/IgM remained negative due to rituximab treatment, and magnetic resonance imaging showed minimal abnormalities, making this a diagnostically challenging case. Despite therapy with intravenous Ig, the patient rapidly declined and died on hospital day 12. Autopsy revealed perivascular and parenchymal chronic inflammation, with an absence of B lymphocytes, and virally infected neurons throughout the central nervous system.
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    TIM-family Proteins Promote Infection of Multiple Enveloped Viruses through Virion-associated Phosphatidylserine
    (Public Library of Science, 2013) Jemielity, Stephanie; Wang, Jinyize J.; Chan, Ying Kai; Ahmed, Asim; Li, Wenhui; Monahan, Sheena; Bu, Xia; Farzan, Michael; Freeman, Gordon; Umetsu, Dale; DeKruyff, Rosemarie H.; Choe, Hyeryun
    Human T-cell Immunoglobulin and Mucin-domain containing proteins (TIM1, 3, and 4) specifically bind phosphatidylserine (PS). TIM1 has been proposed to serve as a cellular receptor for hepatitis A virus and Ebola virus and as an entry factor for dengue virus. Here we show that TIM1 promotes infection of retroviruses and virus-like particles (VLPs) pseudotyped with a range of viral entry proteins, in particular those from the filovirus, flavivirus, New World arenavirus and alphavirus families. TIM1 also robustly enhanced the infection of replication-competent viruses from the same families, including dengue, Tacaribe, Sindbis and Ross River viruses. All interactions between TIM1 and pseudoviruses or VLPs were PS-mediated, as demonstrated with liposome blocking and TIM1 mutagenesis experiments. In addition, other PS-binding proteins, such as Axl and TIM4, promoted infection similarly to TIM1. Finally, the blocking of PS receptors on macrophages inhibited the entry of Ebola VLPs, suggesting that PS receptors can contribute to infection in physiologically relevant cells. Notably, infection mediated by the entry proteins of Lassa fever virus, influenza A virus and SARS coronavirus was largely unaffected by TIM1 expression. Taken together our data show that TIM1 and related PS-binding proteins promote infection of diverse families of enveloped viruses, and may therefore be useful targets for broad-spectrum antiviral therapies.
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    Distinct Patterns of IFITM-Mediated Restriction of Filoviruses, SARS Coronavirus, and Influenza A Virus
    (Public Library of Science, 2011) Radoshitzky, Sheli R.; Becker, Michelle M.; Chi, Xiaoli; Dong, Lian; Longobardi, Lindsay E.; Boltz, Dutch; Kuhn, Jens H.; Bavari, Sina; Denison, Mark R.; Baric, Ralph S.; Huang, I-Chueh; Bailey, Charles; Weyer, Jessica; Chiang, Jessica; Brass, Abraham L.; Ahmed, Asim; Elledge, Stephen; Choe, Hyeryun; Farzan, Michael
    Interferon-inducible transmembrane proteins 1, 2, and 3 (IFITM1, 2, and 3) are recently identified viral restriction factors that inhibit infection mediated by the influenza A virus (IAV) hemagglutinin (HA) protein. Here we show that IFITM proteins restricted infection mediated by the entry glycoproteins (GP1,2) of Marburg and Ebola filoviruses (MARV, EBOV). Consistent with these observations, interferon-β specifically restricted filovirus and IAV entry processes. IFITM proteins also inhibited replication of infectious MARV and EBOV. We observed distinct patterns of IFITM-mediated restriction: compared with IAV, the entry processes of MARV and EBOV were less restricted by IFITM3, but more restricted by IFITM1. Moreover, murine Ifitm5 and 6 did not restrict IAV, but efficiently inhibited filovirus entry. We further demonstrate that replication of infectious SARS coronavirus (SARS-CoV) and entry mediated by the SARS-CoV spike (S) protein are restricted by IFITM proteins. The profile of IFITM-mediated restriction of SARS-CoV was more similar to that of filoviruses than to IAV. Trypsin treatment of receptor-associated SARS-CoV pseudovirions, which bypasses their dependence on lysosomal cathepsin L, also bypassed IFITM-mediated restriction. However, IFITM proteins did not reduce cellular cathepsin activity or limit access of virions to acidic intracellular compartments. Our data indicate that IFITM-mediated restriction is localized to a late stage in the endocytic pathway. They further show that IFITM proteins differentially restrict the entry of a broad range of enveloped viruses, and modulate cellular tropism independently of viral receptor expression.