Cytomegalovirus protein m154 perturbs the adaptor protein-1 compartment mediating broad-spectrum immune evasion.

Cytomegaloviruses (CMVs) are ubiquitous pathogens known to employ numerous immunoevasive strategies that significantly impair the ability of the immune system to eliminate the infected cells. Here, we report that the single mouse CMV (MCMV) protein, m154, downregulates multiple surface molecules involved in the activation and costimulation of the immune cells. We demonstrate that m154 uses its cytoplasmic tail motif, DD, to interfere with the adaptor protein-1 (AP-1) complex, implicated in intracellular protein sorting and packaging. As a consequence of the perturbed AP-1 sorting, m154 promotes lysosomal degradation of several proteins involved in T cell costimulation, thus impairing virus-specific CD8+ T cell response and virus control in vivo. Additionally, we show that HCMV infection similarly interferes with the AP-1 complex. Altogether, we identify the robust mechanism employed by single viral immunomodulatory protein targeting a broad spectrum of cell surface molecules involved in the antiviral immune response.

Increased Risk-Taking Behaviour and Brain-Derived Neurotrophic Factor Val66Met Polymorphism Correlates to Decreased Serum Brain-Derived Neurotrophic Factor Level in Heroin Users.

BACKGROUND: This study has examined the relationships and interactions between serum brain-derived neurotrophic factor (BDNF) levels, BDNF Val66Met polymorphism and self-reported risk-taking behaviour in individuals with a history of heroin use undergoing outpatient treatment in comparison to healthy individuals. METHODS: We enrolled 167 heroin users and 86 healthy subjects and examined serum BDNF levels, Val66Met polymorphism, and personal characteristics using Connor Davidson Resilience Scale, Risk-taking (RT) propensity questionnaire, and Personality Assessment Inventory. RESULTS: Heroin users had significantly higher serum BDNF levels than controls. In addition, serum BDNF levels were significantly higher in Val/Val carriers than in Met/Val or Met/Met in all recruited subjects. Furthermore, a stepwise multiple regression analysis of serum BDNF levels as a dependent variable with related factors showed that in heroin users, Alcohol Use Disorder Identification Test score, anxiety and RT score were found as independent contributors to serum BDNF levels. When performing gene-environment interaction it was additionally found that heroin users with self-reported high risk-taking behaviour had significantly lower levels of serum BDNF among heroin users with the Met allele. CONCLUSIONS: These results indicate that genetic variant Met66 decreased the serum BDNF levels in combination with self-reported risk-taking propensity among heroin users. If results of future work confirm the influence of this combined effect between neurotrophic genotype and risk-taking behaviour, 66Met carriers might require higher levels of intervention to overcome their drug use pattern and risky behaviour.

Murine CMV Expressing the High Affinity NKG2D Ligand MULT-1: A Model for the Development of Cytomegalovirus-Based Vaccines.

The development of a vaccine against human cytomegalovirus (CMV) has been a subject of long-term medical interest. The research during recent years identified CMV as an attractive vaccine vector against infectious diseases and tumors. The immune response to CMV persists over a lifetime and its unique feature is the inflationary T cell response to certain viral epitopes. CMV encodes numerous genes involved in immunoevasion, which are non-essential for virus growth in vitro. The deletion of those genes results in virus attenuation in vivo, which enables us to dramatically manipulate its virulence and the immune response. We have previously shown that the murine CMV (MCMV) expressing RAE-1γ, one of the cellular ligands for the NKG2D receptor, is highly attenuated in vivo but retains the ability to induce a strong CD8+ T cell response. Here, we demonstrate that recombinant MCMV expressing high affinity NKG2D ligand murine UL16 binding protein-like transcript (MULT-1) (MULT-1MCMV) inserted in the place of its viral inhibitor is dramatically attenuated in vivo in a NK cell-dependent manner, both in immunocompetent adult mice and in immunologically immature newborns. MULT-1MCMV was more attenuated than the recombinant virus expressing RAE-1γ. Despite the drastic sensitivity to innate immune control, MULT-1MCMV induced an efficient CD8+ T cell response to viral and vectored antigens. By using in vitro assay, we showed that similar to RAE-1γMCMV, MULT-1 expressing virus provided strong priming of CD8+ T cells. Moreover, MULT-1MCMV was able to induce anti-viral antibodies, which after passing the transplacental barrier protect offspring of immunized mothers from challenge infection. Altogether, this study further supports the concept that CMV expressing NKG2D ligand possesses excellent characteristics to serve as a vaccine or vaccine vector.

Cutting Edge: NKG2D Signaling Enhances NK Cell Responses but Alone Is Insufficient To Drive Expansion during Mouse Cytomegalovirus Infection.

NK cells play a critical role in host defense against viruses. In this study, we investigated the role of NKG2D in the expansion of NK cells after mouse CMV (MCMV) infection. Wild-type and NKG2D-deficient (Klrk1-/- ) Ly49H+ NK cells proliferated robustly when infected with MCMV strains engineered to allow expression of NKG2D ligands, which enhanced the response of wild-type NK cells. Naive NK cells exclusively express NKG2D-L, which pairs only with DAP10, whereas NKG2D-S expressed by activated NK cells pairs with DAP10 and DAP12, similar to Ly49H. However, NKG2D alone was unable to drive robust expansion of Ly49H- NK cells when mice were infected with these MCMV strains, likely because NKG2D-S was only transiently expressed postinfection. These findings demonstrate that NKG2D augments Ly49H-dependent proliferation of NK cells; however, NKG2D signaling alone is inadequate for expansion of NK cells, likely due to only transient expression of the NKG2D-DAP12 complex.