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IntroductionSerological detection of antibodies against SARS-CoV-2 has become an essential tool to test vaccine efficacy and epidemiological surveillance of COVID-19. There have been limited published studies documenting the performance of SARS-CoV-2 antibody assays within hispanic populations.Materials and methodsWe evaluated the diagnostic performance of a chemiluminescence enzyme immunoassay (CLIA) on a set of 1,035 samples including pre-pandemic samples, healthcare workers (HCW), blood donors (BD) and COVID-19 positive confirmed by RT-PCR collected from April to December 2020.ResultsThrough a ROC curve the CLIA test had a high diagnostic performance, with an AUC of 0.9854 (CI95%95.68-100), P 95%95 91.54-99.9), and specificity of 93.8% (CI95%79.8 - 98.9). The diagnostic performance was also evaluated comparing the results with those obtained using other diagnostic techniques. Substantial agreement with the lateral flow chromatography and RT-PCR tests was found, and a high level of agreement with ELISA, with %PPA of 91.3 (CI95%84.0-95.5), % NPA of 97.7 (CI95%96.3-98.6), % OPA of 97.7 (CI95%96.3-98.6) and Cohen’s kappa value of 90.4 (CI95%85.8-94.9). A logistic regression was used to determine which of the independent variables predicted reactivity to CLIA test. A higher age was associated with an odds ratio (OR) of 1.043 (CI95%1.022-1.065), while the presence of at least one chronic disease was associated with an OR of 5.649 (CI95%3.089-10.329) greater likelihood of reactivity.ConclusionsCLIA test exhibited excellent performance making it a suitable test for seroprevalence surveillance at the community level.

There is a dearth of research in Latin America regarding risk and protective factors affecting older adults’ cognition. This study aimed to investigate the factors mediating the association between occupational complexity and late-life cognition and daily function in a sample of Hispanic older adults. Participants (n = 588) aged 65 years and older underwent clinical, functional, and cognitive assessments. Mediation analyses revealed that depressive symptoms mediated the relationship between occupational complexity and cognitive as well as functional outcomes. Results provide evidence that depression may act as a risk factor for worse outcomes, even if older adults had a cognitively demanding occupation.

13 Pág. Centro de Investigación en Sanidad Animal (CISA), Foot and mouth disease is a highly contagious disease affecting cattle, sheep, and swine among other cloven-hoofed animals that imposes serious economic burden by its direct effects on farm productivity as well as on commerce of farmed produce. Vaccination using inactivated viral strains of the different serotypes is an effective protective measure, but has several drawbacks including a lack of cross protection and the perils associated with the large-scale growth of infectious virus. We have previously developed chimeric virus-like particles (VLPs) bearing an FMDV epitope which induced strong specific humoral responses in vaccinated pigs but conferred only partial protection against homologous challenge. While this and other FMD vaccines under development mostly rely on the induction of neutralizing responses, it is thought that induction of specific T-cell responses might improve both cross protective efficacy as well as duration of immunity. Therefore, we here describe the development of a recombinant adenovirus expressing the highly conserved nonstructural FMDV 3D protein as well as its capacity to induce specific T-cell responses in a murine model. We further describe the generation of an FMDV serotype C-specific chimeric VLP and analyze the immunogenicity of two different prime-boost strategies combining both elements in mice. This combination can effectively induce both humoral and cellular FMDV-specific responses eliciting high titers of ELISA and neutralizing antibodies anti-FMDV as well as a high frequency of IFNγ-secreting cells. These results provide the basis for further testing of this anti FMD vaccination strategy in cattle or pig, two of the most relevant natural host of this pathogen., This work as well as the APC were funded by Spanish Ministry of Science and Innovation grant AGL2016-76445-R and Comunidad de Madrid co-financed EC-FEDER funds S2018/BAA-4370 (to E.B. and A.A.) as well as by PID2019-107145RB-100 (to E.B.). G.R. was a holder of a PhD fellowship from the Spanish Ministry of Science and Innovation (FPI programme)

Nearly 50 different mouse retinal ganglion cell (RGC) types sample the visual scene for distinct features. RGC feature selectivity arises from its synapses with a specific subset of amacrine (AC) and bipolar cell (BC) types, but how RGC dendrites arborize and collect input from these specific subsets remains poorly understood. Here we examine the hypothesis that RGCs employ molecular recognition systems to meet this challenge. By combining calcium imaging and type-specific histological stains we define a family of circuits that express the recognition molecule Sidekick 1 (Sdk1) which include a novel RGC type (S1-RGC) that responds to local edges. Genetic and physiological studies revealed that Sdk1 loss selectively disrupts S1-RGC visual responses which result from a loss of excitatory and inhibitory inputs and selective dendritic deficits on this neuron. We conclude that Sdk1 shapes dendrite growth and wiring to help S1-RGCs become feature selective.

22 Pág. Centro de Investigación en Sanidad Animal (CISA), Currently there is a clear trend towards the establishment of virus-like particles (VLPs) as a powerful tool for vaccine development. VLPs are tunable nanoparticles that can be engineered to be used as platforms for multimeric display of foreign antigens. We have previously reported that VLPs derived from rabbit hemorrhagic disease virus (RHDV) constitute an excellent vaccine vector, capable of inducing specific protective immune responses against inserted heterologous T-cytotoxic and B-cell epitopes. Here, we evaluate the ability of chimeric RHDV VLPs to elicit immune response and protection against Foot-and-Mouth disease virus (FMDV), one of the most devastating livestock diseases. For this purpose, we generated a set of chimeric VLPs containing two FMDV-derived epitopes: a neutralizing B-cell epitope (VP1 (140-158)) and a T-cell epitope [3A (21-35)]. The epitopes were inserted joined or individually at two different locations within the RHDV capsid protein. The immunogenicity and protection potential of the chimeric VLPs were analyzed in the mouse and pig models. Herein we show that the RHDV engineered VLPs displaying FMDV-derived epitopes elicit a robust neutralizing immune response in mice and pigs, affording partial clinical protection against an FMDV challenge in pigs., This work was supported by Spanish Ministry of Science and Innovation (grants AGL2016-76445-R to EB and AA; PID2019-107145RB-I00 to EB and BFU2017-88736- to JRC) and Comunidad de Madrid co-financed with ECFEDER funds (P2018/BAA-4370 PLATESA 2 to EB and P2018/NMT-4389 to JRC). GR and NM were holders of a PhD fellowship from the Spanish Ministry of Science and Innovation (FPI programme) and CPM was a PhD fellow of the La Caixa Foundation International Fellowship Program (La Caixa/CNB).

Novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiologic agent of the ongoing coronavirus disease 2019 (COVID-19) pandemic, which has reached 28 million cases worldwide in eight months. The serological detection of antibodies against the virus will play a pivotal role in complementing molecular tests to improve diagnostic accuracy, contact tracing, vaccine efficacy testing and seroprevalence surveillance. Here, we aimed first to evaluate a lateral flow assay’s ability to identify specific IgM and IgG antibodies against SARS-CoV-2 and second, to report the seroprevalence of these antibodies among health care workers and healthy volunteer blood donors in Panama. We recruited study participants between April 30thand July 7th, 2020. For the test validation and performance evaluation, we analyzed serum samples from participants with clinical symptoms and confirmed positive RT-PCR for SARS-CoV-2, participants with other confirmed infectious diseases, and a set of pre-pandemic serum samples. We used two by two table analysis to determine the test sensitivity and specificity as well as the kappa agreement value with a 95% confidence interval. Then, we used the lateral flow assay to determine seroprevalence among serum samples from COVID-19 patients, potentially exposed health care workers, and healthy volunteer donors. Our results show this assay reached a positive percent agreement of 97.2% (95% CI 84.2-100.0%) for detecting both IgM and IgG. The assay showed akappaof 0.898 (95%CI 0.811-0.985) and 0.918 (95% CI 0.839-0.997) for IgM and IgG, respectively. The evaluation of serum samples from hospitalized COVID-19 patients indicates a correlation between test sensitivity and the number of days since symptom onset; the highest positive percent agreement (87% (95% CI 67.0-96.3%)) was observed at ≥15 days post-symptom onset. We found an overall antibody seroprevalence of 11.6% (95% CI 8.5-15.8%) among both health care workers and healthy blood donors. Our findings suggest this lateral flow assay could contribute significantly to implementing seroprevalence testing in locations with active community transmission of SARS-CoV-2.

During development, neurons navigate a tangled thicket of thousands of axons and dendrites to synapse with just a few specific targets. This phenomenon termed wiring specificity, is critical to the assembly of neural circuits and the way neurons manage this feat is only now becoming clear. Recent studies in the mouse retina are shedding new insight into this process. They show that specific wiring arises through a series of stages that include: directed axonal and dendritic growth, the formation of neuropil layers, positioning of such layers, and matching of co-laminar synaptic partners. Each stage appears to be directed by a distinct family of recognition molecules, suggesting that the combinatorial expression of such family members might act as a blueprint for retinal connectivity. By reviewing the evidence in support of each stage, and by considering their underlying molecular mechanisms, we attempt to synthesize these results into a wiring model which generates testable predictions for future studies. Finally, we conclude by highlighting new optical methods that could be used to address such predictions and gain further insight into this fundamental process.

COVID-19 is the name of the acute respiratory disease caused by the new coronavirus SARS-CoV-2, a close relative of those that caused the severe outbreaks of SARS and MERS several years ago. Since first appearance on December of 2019, the COVID-19 pandemic has cause extremely high levels of mortality, morbidity, global economic breakdown and the consequent human suffering. While vaccination efforts are not extensive and rapid enough, the main tools to keep the virus under control are still keeping physical distancing, reinforce personal hygiene measures, using masks and early diagnosis of virus infected persons, either symptomatic or not. The main diagnostic test for the confirmation of symptomatic individuals is the detection of viral RNA by reverse transcriptase – quantitative real time PCR (RT-PCR). Additionally, serology techniques, such as ELISA are extremely useful to measure the antibodies generated in humans after virus contact, as well as the direct presence of viral antigens. In this study we aim to assemble and evaluate four ELISAs assays to measure the presence of IgG or IgM specific for the viral Spike protein in COVID-19 patients, using either the full recombinant SARS-CoV-2 Spike protein or the fragment corresponding to the receptor binding domain. As a control, we also analyzed a group of prepandemic serum samples obtained before 2017.Strong reactivity was observed against both antigens. A few prepandemic samples displayed high OD values, suggesting the possibility of some crossreactivity. All four assays show very good repeatability, both intra- and inter-assay; however, no clear relationship could be detected between positivity and time of sample collection for serology. Receiver operating characteristic analysis allowed the definition of cutoffs and evaluation of performance for each ELISA by estimation of the area under the curve. This performance parameter was high for all tests (AUC range: 0.98-0.995). Multiple comparisons between tests revealed no significant difference between each other (P values: 0.24-0.95). Our results show that both antigens are very effective to reveal both specific IgG and IgM antibodies, with high sensitivity (range 0.929-0.99) and specificity (range 0.933-0.977). The estimated congruence with the RT-PCR test, as estimated by Cohen’s Kappa, indicates a high agreement in all cases (range 0.874-0.937). This test will allow health authorities to have a new tool to estimate seroprevalence, and to manage and improve the serious sanitary situation created by this virus.

Ovine interferon tau (IFN-τ) is a unique type I interferon with low toxicity and a broad host range in vivo . We report the generation of a nonreplicative recombinant adenovirus expressing biologically active IFN-τ. Using the B6.A2G-Mx1 mouse model, we showed that single-dose intranasal administration of recombinant Ad5-IFN-τ can effectively prevent lethality and disease induced by highly virulent hv-PR8 influenza virus by activating the interferon response and preventing viral replication.