Signal Peptide Cleavage from GP5 of PRRSV: A Minor Fraction of Molecules Retains the Decoy Epitope,a Presumed Molecular Cause for Viral Persistence

Porcine reproductive and respiratory syndrome virus (PRRSV) is the major pathogen in the pig industry. Variability of the antigens and persistence are the biggest challenges for successful control and elimination of the disease. GP5, the major glycoprotein of PRRSV, is considered an important target of neutralizing antibodies, which however appear only late in infection. This was attributed to the presence of a “decoy epitope” located near a hypervariable region of GP5. This region also harbors the predicted signal peptide cleavage sites and (dependent on the virus strain) a variable number of potential N-glycosylation sites. Molecular processing of GP5 has not been addressed experimentally so far: whether and where the signal peptide is cleaved and (as a consequence) whether the “decoy epitope” is present in virus particles. We show that the signal peptide of GP5 from the American type 2 reference strain VR-2332 is cleaved, both during in vitro translation in the presence of microsomes and in transfected cells. This was found to be independent of neighboring glycosylation sites and occurred in a variety of porcine cells for GP5 sequences derived from various type 2 strains. The exact signal peptide cleavage site was elucidated by mass spectrometry of virus-derived and recombinant GP5. The results revealed that the signal peptide of GP5 is cleaved at two sites. As a result, a mixture of GP5 proteins exists in virus particles, some of which still contain the “decoy epitope” sequence. Heterogeneity was also observed for the use of glycosylation sites in the hypervariable region. Lastly, GP5 mutants were engineered where one of the signal peptide cleavage sites was blocked. Wildtype GP5 exhibited exactly the same SDS-PAGE mobility as the mutant that is cleavable at site 2 only. This indicates that the overwhelming majority of all GP5 molecules does not contain the “decoy epitope”.     

High Levels of Asymmetric Dimethylarginine Are Strongly Associated with Low HDL in Patients with Acute Myocardial Infarction

Objectives

Low levels of high-density lipoprotein (HDL) cholesterol are associated with an increased risk of acute myocardial infarction possibly through impaired endothelial atheroprotection and decreased nitric oxide (NO) bioavailability. Asymmetric dimethylarginine (ADMA) mediates endothelial function by inhibiting nitric oxide synthase activity. In patients with acute myocardial infarction, we investigated the relationship between serum levels of HDL and ADMA.

Approach and Results

Blood samples from 612 consecutive patients hospitalized for acute MI <24 hours after symptom onset were taken on admission. Serum levels of ADMA, its stereoisomer, symmetric dimethylarginine (SDMA) and L-arginine were determined using high-performance liquid chromatography. Patients with low HDL (<40 mg/dL for men and <50 mg/dL for women) were compared with patients with higher HDL. Most patients (59%) had low HDL levels. Median ADMA levels were markedly higher in the low HDL group (0.69 vs. 0.50 µmole/L, p<0.001). In contrast, SDMA and L-arginine levels were similar for the two groups (p = 0.120 and p = 0.064). Notably, ADMA, but not SDMA or L-arginine, was inversely correlated with HDL (r = −0.311, p<0.001). In stratified analysis, this relationship was only found for low HDL levels (r = −0.265, p<0.001), but not when HDL levels were higher (r = −0.077, p = 0.225). By multivariate logistic regression analysis, ADMA level was strongly associated with low HDL levels (OR(95%CI):6.06(3.48–10.53), p<0.001), beyond traditional confounding factors.

Conclusions

Our large population-based study showed for the first time a strong inverse relationship between HDL and ADMA in myocardial infarction patients, suggesting a functional interaction between HDL and endothelium, beyond metabolic conditions associated with low HDL levels.     

Similarity of Cortical Activity Patterns Predicts generalization Behavior

Humans and animals readily generalize previously learned knowledge to new situations. Determining similarity is critical for assigning category membership to a novel stimulus. We tested the hypothesis that category membership is initially encoded by the similarity of the activity pattern evoked by a novel stimulus to the patterns from known categories. We provide behavioral and neurophysiological evidence that activity patterns in primary auditory cortex contain sufficient information to explain behavioral categorization of novel speech sounds by rats. Our results suggest that category membership might be encoded by the similarity of the activity pattern evoked by a novel speech sound to the patterns evoked by known sounds. Categorization based on featureless pattern matching may represent a general neural mechanism for ensuring accurate generalization across sensory and cognitive systems.     

Overnight Resting of PBMC Changes Functional Signatures of Antigen Specific T- Cell Responses: Impact for Immune Monitoring within Clinical Trials

Polyfunctional CD4 or CD8 T cells are proposed to represent a correlate of immune control for persistent viruses as well as for vaccine mediated protection against infection. A well-suited methodology to study complex functional phenotypes of antiviral T cells is the combined staining of intracellular cytokines and phenotypic marker expression using polychromatic flow cytometry. In this study we analyzed the effect of an overnight resting period at 37°C on the quantity and functionality of HIV-1, EBV, CMV, HBV and HCV specific CD4 and CD8 T-cell responses in a cohort of 21 individuals. We quantified total antigen specific T cells by multimer staining and used 10-color intracellular cytokine staining (ICS) to determine IFNγ, TNFα, IL2 and MIP1β production. After an overnight resting significantly higher numbers of functionally active T cells were detectable by ICS for all tested antigen specificities, whereas the total number of antigen specific T cells determined by multimer staining remained unchanged. Overnight resting shifted the quality of T-cell responses towards polyfunctionality and increased antigen sensitivity of T cells. Our data suggest that the observed effect is mediated by T cells rather than by antigen presenting cells. We conclude that overnight resting of PBMC prior to ex vivo analysis of antiviral T-cell responses represents an efficient method to increase sensitivity of ICS-based methods and has a prominent impact on the functional phenotype of T cells.     

Impacts of Intergroup Interactions on Intragroup Behavioral Changes in Javan Gibbons (Hylobates moloch)

International Journal of Primatology - Agonistic intergroup interactions can cause individual costs such as physical injuries, increased physiological stress, and disrupted intragroup social...     

Corvids avoid odd evaluation by following simple rules in a risky exchange task

In their natural environment, animals often make decisions crucial for survival, such as choosing the best patch or food, or the best partner to cooperate. The choice can be compared to a gamble with an outcome that is predictable but not certain, such as rolling a dice. In economics, such a situation is called a risky context. Several models show that although individuals can generally evaluate the odds of each potential outcome, they can be subject to errors of judgment or choose according to decision-making heuristics (simple decision rules). In non-human primates, similar errors of judgment have been reported and we have recently shown that they also use a decisional heuristics when confronted with a risky choice in an exchange task. This suggests a common evolutionary origin to the mechanisms underlying decision-making under risk in primates. However, whether the same mechanisms are also present in more distantly related taxa needs to be further investigated. Other social species, like corvids, are renowned for their advanced cognitive skills and may show similar responses. Here, we analyse data on corvids (carrion crows, hooded crows, common ravens and rooks) tested in a risky exchange task comparable to the one used in non-human primates. We investigated whether corvids could exchange according to the odds of success or, alternatively, whether they used a heuristic similar to the one used by non-human primates. Instead, most corvids chose a course of action (either a low or high exchange rate) that remained constant throughout the study. In general, corvids’ mean exchange rates were lower compared to non-human primates, indicating that they were either risk-adverse or that they do not possess the cognitive capabilities to evaluate odds. Further studies are required to evaluate the flexibility in exchange abilities of these birds in exchange abilities of these birds.     

Prognostic factors and predictors of outcome in patients with COVID-19 and related pneumonia: a retrospective cohort study

The aim of the present study was to simultaneously assess several potential predictors of outcome (co-morbidity, previous and in-hospital treatment, radiologic Brixia score) in patients with COVID-19.This retrospective cohort study included 258 consecutive patients with confirmed COVID-19 admitted to a medical ward at Montichiari Hospital, Brescia, Italy from February 28th to April 30rd, 2020. Patients had SARS-CoV-2 related pneumonia with respiratory failure, and were treated with hydroxychloroquine and lopinavir plus ritonavir. In some patients, additional treatment with tocilizumab, dexamethasone and enoxaparin was adopted. Outcomes (death or recovery) were assessed at the end of the discharge period or at the end of the follow-up (August 2020).During hospitalization, 59 patients died, while 6 died after discharge. The following variables were demonstrated to be associated with a worse prognosis: Radiologic Brixia score higher than 8, presence at baseline of hypertension, diabetes, chronic obstructive pulmonary disease, heart disease, cancer, previous treatment with ACE-inhibitors or anti-platelet drugs. Anticoagulant treatment during hospital admission with enoxaparin at a dose higher than 4000 U once daily was associated with a better prognosis.In conclusion, our study demonstrates that some co-morbidities and cardiovascular risk factors may affect prognosis. The radiologic Brixia score may be a useful tool to stratify the risk of death at baseline. Anticoagulant treatment with enoxaparin might be associated to a clinical benefit in terms of survival in patients with COVID-19.