Human APOBEC3F (huA3F) potently restricts the infectivity of HIV-1 in the absence of the viral accessory protein virion infectivity factor (Vif). Vif functions to preserve viral infectivity by triggering the degradation of huA3F but not rhesus macaque A3F (rhA3F). Here, we use a combination of deletions, chimeras, and systematic mutagenesis between huA3F and rhA3F to identify Glu 324 as a critical determinant of huA3F susceptibility to HIV-1 Vif-mediated degradation. A structural model of the C-terminal deaminase domain of huA3F indicates that Glu 324 is a surface residue within the ␣4 helix adjacent to residues corresponding to other known Vif susceptibility determinants in APOBEC3G and APOBEC3H. This structural clustering suggests that Vif may bind a conserved surface present in multiple APOBEC3 proteins.Human APOBEC3 proteins including APOBEC3F (huA3F) and APOBEC3G (huA3G) are DNA cytidine deaminases that restrict the infectivity of HIV-1 in target cells following virion incorporation in producer cells (recently reviewed in Refs. 1-3). HIV-1 overcomes this restriction activity by utilizing its accessory protein virion infectivity factor (Vif) 4 to facilitate the degradation of APOBEC3 proteins in producer cells, thus preventing particle incorporation and restriction.Previously, several groups identified specific changes in the N-terminal deaminase domain (NTD) of huA3G that affect the ability of HIV-1 Vif to neutralize this restriction factor (4 -10). The first of these studies sought to determine the basis for the observation that the Vif proteins of the lentiviruses infecting different species neutralize the A3G proteins of their natural host species but not the A3G proteins of other species (11). For example, African green monkey A3G (agmA3G) is susceptible to Vif from the simian immunodeficiency virus (SIV) that naturally infects Chlorocebus aethiops (agmSIV) but not to HIV-1 Vif, whereas huA3G is susceptible to HIV-1 Vif but not to agmSIV Vif. By substituting agmA3G residues into huA3G where the two differed, several groups identified Asp 128 as a critical determinant of this species specificity (4 -7). Subsequent mutational analyses have confirmed that huA3G Asp 128 and surrounding residues including Asp 130 impact HIV-1 Vif-mediated degradation (8 -10).More recently, two reports showed that, in contrast with huA3G, huA3F is recognized at its C-terminal deaminase domain (CTD) by HIV-1 Vif (9, 12). One of these groups further narrowed the determinants of this recognition to amino acids 283-300, although individual amino acid changes critical for HIV-1 Vif susceptibility were not identified in a manner analogous to the huA3G studies cited above. Thus, the residues of huA3F critical for the ability of HIV-1 Vif to bind and degrade this restriction factor are presently unknown.Here, we identify a critical determinant of huA3F susceptibility to HIV-1 Vif by comparing huA3F with the closely related but HIV-1 Vif-resistant rhA3F (13,14). Using chimeras between these orthologs as well as single-domain studies, ...

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A237primary target for drug-seeking patients, this pilot study was conducted to validate a survey instrument designed to assess emergency physicians (EPs) intention to use the recently available Texas PMP. Methods: A cross-sectional survey of EPs was conducted at a statewide emergency medicine conference. A 34-item questionnaire, based on the Technology Acceptance Model (TAM), was developed to assess EPs intention to use the Texas PMP. Items related to technology acceptance (perceived ease of use, perceived usefulness, attitude, and intention) were assessed using 5-point Likert scale responses (1= strongly disagree to 5= strongly agree). The survey expanded on a previous exploratory survey of EPs. Correlation analyses were used to validate the survey instrument scales. Results: Of the 45 respondents, most were male (68.9%), attending EPs (57.8%), with 10.8±11.1 years in emergency medicine, from a community hospital setting (55.6%), and were users of the Texas PMP (51.2%). Among those who were not registered, 39.2% reported lack of awareness as the primary reason for not being registered. Standardized Cronbach's alphas for the constructs of perceived ease of use, perceived usefulness, attitude, and intention for PMP users were 0.88, 0.90, 0.74, and 0.84, respectively; and 0.77, 0.87, 0.84, and 0.74, respectively for PMP non-users. ConClusions: Considering the ED as a source of diversion, it is important to understand EPs utilization of PMPs. EPs use of PMPs may help to mitigate the economic burden associated with the non-medical use of prescription opioids, while improving patient outcomes. Future studies using this survey instrument are needed to further assess the predictive utility.