Stinging the Conscience: A Case of Severe Hymenoptera Anaphylaxis and the Need for Provider Awareness.

Hymenoptera venom allergy accounts for approximately 17% of all cases of anaphylaxis. Insect stings are a common occurrence across the world, with significant impact on active duty personnel. Venom immunotherapy (VIT) provides an effective treatment for those with systemic reactions to insect stings and other similar indications. We present a case of severe reaction to hymenoptera venom requiring an epinephrine drip and provide an overview for primary care providers on who should be referred to allergy or an allergist, carry an epinephrine auto-injector, and be a candidate for VIT. As this case demonstrates, such a framework is critical as even patients with a history of severe reactions may have a delay in referral to specialty care. The preventable morbidity and mortality associated with hymenoptera venom allergy represents a clear imperative to identify those service members at risk for future systemic symptoms and to refer them for assessment and VIT therapy. Allergy evaluation and treatment with VIT affords the opportunity for service members to be retained in the military and remain medically fit and ready for deployment around the world.

Campylobacter fetus bacteremia in an immunocompetent traveler.

Campylobacter fetus bacteremia is a rare human infection that occurs almost exclusively in the setting of advanced age, immunosuppression, human immunodeficiency virus infection, alcoholism, or recent gastrointestinal surgery. This report of C. fetus bacteremia in a 39-year-old immunocompetent traveler who ate raw beef identifies C. fetus as a potential emerging pathogen in normal hosts.

The structure of AAVrh32.33, a novel gene delivery vector.

The Adeno-associated viruses (AAVs) are being developed as gene delivery vectors for therapeutic clinical applications. However, the host antibody immune response directed against their capsid, prevalent in ∼40-70% of the general population, depending on serotype, negatively impacts efficacy. AAVrh32.33, a novel vector developed from rhesus macaques isolates, has significantly lower seroprevalence in human populations compared to AAV2 and AAV8, which are both in clinical use. To better understand the capsid determinants of this differential immune response to AAVrh32.33, its structure was determined by X-ray crystallography to 3.5 Å resolution. The capsid viral protein (VP) structure conserves the eight-stranded ß-barrel core and αA helix reported for other parvoviruses and the distinct capsid surface topology of the AAVs: a depression at the icosahedral twofold axis, three protrusions surrounding the threefold axis, and a depression surround a cylindrical channel at the fivefold axis. A comparison to AAV2, AAV4, and AAV8, to which AAVrh32.33 shares ∼61%, ∼81%, and ∼63% identity, respectively, identified differences in previously defined AAV VP structurally variable regions (VR-1 to VR-IX) which function as receptor attachment, transduction efficiency, and/or antigenic determinants. This structure thus provides a 3D platform for capsid engineering in ongoing efforts to develop AAVrh32.33, as well as other AAV serotypes, for tissue targeted gene-therapy applications with vectors that can evade pre-existing antibody responses against the capsid. These features are required for full clinical realization of the promising AAV gene delivery system.

Mapping the structural determinants responsible for enhanced T cell activation to the immunogenic adeno-associated virus capsid from isolate rhesus 32.33.

Avoiding activation of immunity to vector-encoded proteins is critical to the safe and effective use of adeno-associated viral (AAV) vectors for gene therapy. While commonly used serotypes, such as AAV serotypes 1, 2, 7, 8, and 9, are often associated with minimal and/or dysfunctional CD8(+) T cell responses in mice, the threshold for immune activation appears to be lower in higher-order species. We have modeled this discrepancy within the mouse by identifying two capsid variants with differential immune activation profiles: AAV serotype 8 (AAV8) and a hybrid between natural rhesus isolates AAVrh32 and AAVrh33 (AAVrh32.33). Here, we aimed to characterize the structural determinants of the AAVrh32.33 capsid that augment cellular immunity to vector-encoded proteins or those of AAV8 that may induce tolerance. We hypothesized that the structural domain responsible for differential immune activation could be mapped to surface-exposed regions of the capsid, such as hypervariable regions (HVRs) I to IX of VP3. To test this, a series of hybrid AAV capsids was constructed by swapping domains between AAV8 and AAVrh32.33. By comparing their ability to generate transgene-specific T cells in vivo versus the stability of transgene expression in the muscle, we confirmed that the functional domain lies within the VP3 portion of the capsid. Our studies were able to exclude the regions of VP3 which are not sufficient for augmenting the cellular immune response, notably, HVRs I, II, and V. We have also identified HVR IV as a region of interest in conferring the efficiency and stability of muscle transduction to AAVrh32.33.