A Germline-Targeting Chimpanzee SIV Envelope Glycoprotein Elicits a New Class of V2-Apex Directed Cross-Neutralizing Antibodies.

HIV-1 and its SIV precursors share a broadly neutralizing antibody (bNAb) epitope in variable loop 2 (V2) at the envelope glycoprotein (Env) trimer apex. Here, we tested the immunogenicity of germ line-targeting versions of a chimpanzee SIV (SIVcpz) Env in human V2-apex bNAb heavy-chain precursor-expressing knock-in mice and as chimeric simian-chimpanzee immunodeficiency viruses (SCIVs) in rhesus macaques (RMs). Trimer immunization of knock-in mice induced V2-directed NAbs, indicating activation of V2-apex bNAb precursor-expressing mouse B cells. SCIV infection of RMs elicited high-titer viremia, potent autologous tier 2 neutralizing antibodies, and rapid sequence escape in the canonical V2-apex epitope. Six of seven animals also developed low-titer heterologous plasma breadth that mapped to the V2-apex. Antibody cloning from two of these animals identified multiple expanded lineages with long heavy chain third complementarity determining regions that cross-neutralized as many as 7 of 19 primary HIV-1 strains, but with low potency. Negative stain electron microscopy (NSEM) of members of the two most cross-reactive lineages confirmed V2 targeting but identified an angle of approach distinct from prototypical V2-apex bNAbs, with antibody binding either requiring or inducing an occluded-open trimer. Probing with conformation-sensitive, nonneutralizing antibodies revealed that SCIV-expressed, but not wild-type SIVcpz Envs, as well as a subset of primary HIV-1 Envs, preferentially adopted a more open trimeric state. These results reveal the existence of a cryptic V2 epitope that is exposed in occluded-open SIVcpz and HIV-1 Env trimers and elicits cross-neutralizing responses of limited breadth and potency. IMPORTANCE An effective HIV-1 vaccination strategy will need to stimulate rare precursor B cells of multiple bNAb lineages and affinity mature them along desired pathways. Here, we searched for V2-apex germ line-targeting Envs among a large set of diverse primate lentiviruses and identified minimally modified versions of one chimpanzee SIV Env that bound several human V2-apex bNAb precursors and stimulated one of these in a V2-apex bNAb precursor-expressing knock-in mouse. We also generated chimeric simian-chimpanzee immunodeficiency viruses and showed that they elicit low-titer V2-directed heterologous plasma breadth in six of seven infected rhesus macaques. Characterization of this antibody response identified a new class of weakly cross-reactive neutralizing antibodies that target the V2-apex, but only in occluded-open Env trimers. The existence of this cryptic epitope, which in some Env backgrounds is immunodominant, needs to be considered in immunogen design.

Markers for intimate partner violence in the emergency department setting.

PURPOSE: Intimate partner violence (IPV) is a serious, under-reported public health problem in the United States. Pilot studies suggested that injury location, that is, head, neck, or face, was a sensitive but nonspecific marker for IPV-related injuries. This study's goal was to determine whether adding a second element to the diagnostic protocol-response to an IPV-screening questionnaire-improved the specificity of the protocol. MATERIALS AND METHODS: We used a cross-sectional study design and a sample composed of women presenting to the emergency department for evaluation and management of injuries of non-verifiable etiology. The predictor study variables were injury location (head, neck, or face vs other), responses to a verbal questionnaire (Partner Violence Screen or Woman Abuse Screening Tool), and the combination of both elements. By combining both elements, the probability for IPV-related injury was classified as high or low. The outcome variable was self-report of injury etiology (IPV or other etiology). Appropriate univariate and bivariate statistics were computed, including estimates of sensitivity, specificity, positive and negative predictive values, and relative risk. RESULTS: The sample was composed of 300 women with a mean age of 36.5 years. The frequency of self-reported IPV-related injury was 32.3%. The sensitivities and specificities for injury location and the questionnaires combined ranged from 86.5% to 91.8% and 93.1% to 96.1%, respectively. CONCLUSIONS: The study findings suggest that combining information regarding injury location and the results of a screening questionnaire was a better predictor of a woman's likelihood to report IPV-related injuries than either modality alone.