Preliminary evaluation of probiotic properties of Lactobacillus strains isolated from Sardinian dairy products

Twenty-three Lactobacillus strains of dairy origin were evaluated for some functional properties relevant to their use as probiotics. A preliminary subtractive screening based on the abilities to inhibit the growth of microbial pathogens and hydrolyze conjugated bile salts was applied, and six strains were selected for further characterization including survival under gastrointestinal environmental conditions, adhesion to gut epithelial tissue, enzymatic activity, and some safety properties. All selected strains maintained elevated cell numbers under conditions simulating passage through the human gastrointestinal tract, well comparable to the values obtained for the probiotic strain Lactobacillus rhamnosus GG, and were able to adhere to Caco-2 cells to various extents (from 3 to 20%). All strains exhibited high aminopeptidase, and absent or very low proteolytic and strong β-galactosidase activities; none was found to be haemolytic or to produce biogenic amines and all were susceptible to tetracycline, chloramphenicol, erythromycin, ampicillin, and amoxicillin/clavulanic acid. Our results indicate that the Lactobacillus strains analyzed could be considered appropriate probiotic candidates, due to resistance to GIT simulated conditions, antimicrobial activity, adhesion to Caco-2 cell-line, and absence of undesirable properties. They could be used as adjunct cultures for contributing to the quality and health related functional properties of dairy products

Increased Hepatitis E Virus Seroprevalence Correlates with Lower CD4+Cell Counts in HIV-Infected Persons in Argentina

Hepatitis E virus (HEV) is a single-stranded RNA virus that can cause hepatitis in an epidemic fashion. HEV usually causes asymptomatic or limited acute infections in immunocompetent individuals, whereas in immunosuppressed individuals such as transplant recipients, HEV can cause chronic infections. The risks and outcomes of HEV co-infection in patients infected with human immunodeficiency virus (HIV) are poorly characterized. We used a third generation immunoassay to measure serum IgG antibodies specific for HEV in 204 HIV-infected individuals from Argentina and a control group of 433 HIV-negative individuals. We found 15 of 204 (7.3%, 95% CI 3.74-10.96%) individuals in the HIV-positive group to have positive HEV IgG levels suggestive of previous infection, compared to 19 of 433 (4.4%, 95% CI 2.5-6.3%) individuals in the HIV-negative control group (p = 0.12). Among HIV-positive individuals, those with HEV seropositivity had lower CD4 counts compared to those that were HEV seronegative (average CD4 count of 234 vs 422 mm(3), p = 0.01), indicating that patients with lower CD4 counts were more likely to be HEV IgG positive. Moreover, HEV seropositivity in patients with CD4 counts <200 mm(3) was 16%, compared to 4.5% in those with CD4 counts >200 mm(3) (p = 0.012). We found a positive PCR result for HEV in one individual. Our study found that increased seroprevalence of HEV IgG correlated with lower CD4 counts in HIV-infected patients in Argentina

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Abstract:  Although the nasopharyngeal swab (NPS) is considered the optimal sample for the diagnosis of SARS-CoV-2 infection, the nasal swab (NS) is usually used since it is less invasive and of greater adherence. Our aim was to evaluate the performance of the nasal antigen detection test as a massive testing strategy in outpatients in Córdoba. Two hundred and forty-eight samples from persons (symptomatic n=126, asymptomatic n=122) who voluntarily agreed to the simultaneous collection of samples of NPS, NS and oropharyngeal swab (OPS) for the detection of the rapid antigen PanbioTM COVID-19 Ag Rapid Test (Ag-NS), PanbioTM COVID-19 Ag Rapid Test (Ag-NPS) and real time RT-PCR for RNA detection in OPS (DisCoVery SARS-CoV-2 Nucleic Acid Detection Kit) were included. Fifty samples resulted positive for RNA-SARS-CoV-2 molecular detection, from which 45 and 40 were positive for Ag-NPS and Ag-NS, respectively. Five samples were positive only for Ag-NPS and negative for Ag-NS [symptomatic n=4 and asymptomatic n=1, mean Ct=30.7 (28.3-32.6)]. One sample was false positive for Ag-NPS. Five samples were false negative by both rapid Ag tests [symptomatic n=3, asymptomatic n=2, mean Cts=33.3 (30.8-36.2)]. The Ag-NPS rapid test yielded a sensitivity of 90.0% (95% CI: 80.7-99.3) and the Ag-NS rapid test a sensitivity of 80.0% (95% CI: 67.9 -92.1), kappa index = 0.89. In symptomatic patients, the Ag-NPS test presented a sensitivity of 91.9% (95% CI: 81.8-100.0), while the Ag-NS test had a sensitivity of 81.1% (95% CI: 67.1-95.1), kappa index=0.90. In asymptomatic patients, the sensitivity for the Ag-NPS test was 86.6% (95% CI: 61.2-100.0) and 76.9% (95% CI: 50.2-100.0) for Ag-NS, kappa index=0.82. The results obtained show an adequate sensitivity of the Ag-NPS (90%) and Ag-NS (80%) tests for the detection of SARS-CoV-2 infection. Although the use of NS has lower sensitivity, in accordance with previous studies, the results found indicate that its use would be acceptable, due to its operative capacity as it is less invasive, increasing adherence and the evaluation of a greater number of patients, improving efficient contact management and early isolation.Resumen:  Si bien el hisopado nasofaríngeo (HNF) es considerado la muestra óptima para el diagnóstico de la infección por SARS-CoV-2, el hisopado nasal (HN) es usualmente utilizado ya que resulta menos invasivo y de mayor adherencia. El objetivo fue evaluar el rendimiento de la prueba de detección de antígeno nasal como estrategia de testeos masivos en pacientes ambulatorios de Córdoba. Se incluyeron 248 muestras de personas (sintomáticas n=126, asintomáticas n=122) que accedieron voluntariamente a la toma simultánea de muestras de HNF, HN e hisopado orofaríngeo (HOF) para la detección de antígeno rápido PanbioTM COVID-19 Ag Rapid Test (Ag-HN), PanbioTM COVID-19 Ag Rapid Test (Ag-HNF) y qPCR para la detección de RNA en HOF (DisCoVery SARS-CoV-2 Nucleic Acid Detection Kit). Cincuenta muestras resultaron RNA-SARS-CoV-2 positivas, de las cuales 45 y 40 fueron positivas para las pruebas de Ag-HNF y Ag-HN, respectivamente. Cinco muestras resultaron positivas sólo para Ag-HNF y negativas para Ag-HN [sintomáticas n=4 y asintomáticas n=1, Cts promedio=30,7 (28,3-32.6)]. Una muestra resultó falsa positiva para Ag-HNF. Cinco muestras resultaron falsas negativas por ambos test rápidos de Ag [sintomáticas n=3, asintomáticas n=2, Cts promedio=33,3 (30,8-36,2)]. El test rápido de Ag-HNF arrojó una sensibilidad del 90,0% (IC 95%: 80,7-99,3) y el test rápido Ag-HN una sensibilidad del 80,0% (IC 95%: 67,9-92,1), índice kappa=0,89. En pacientes sintomáticos, el test de Ag-HNF presentó una sensibilidad del 91,9% (IC 95%: 81,8-100,0), mientras que el de Ag-HN una sensibilidad del 81,1% (IC 95%: 67,1-95,1), índice kappa=0,90. En pacientes asintomáticos, la sensibilidad para el test de Ag-HNF fue 86,6% (IC 95%: 61,2-100,0) y 76,9% (IC 95%: 50,2-100,0) para Ag-HN, índice kappa=0,82. Los resultados obtenidos muestran una adecuada sensibilidad de los tests Ag-HNF (90%) y Ag-HN (80%) para la detección de la infección por SARS-CoV-2. Si bien el uso de HN posee menor sensibilidad, en concordancia con estudios previos, los resultados hallados indican que su uso sería aceptable, debido a su capacidad operativa por ser menos invasivo, aumentando la adherencia y la evaluación de una mayor cantidad de pacientes, mejorando la eficiencia en el manejo de los contactos y el aislamiento precoz.

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Abstract:  Hepatitis E virus (HEV), which causes acute hepatitis, can progress to chronicity in immunosuppressed patients. Transfusion transmission has been reported, being asymptomatic carriers a virus reservoir and a potential threat to transfusion safety. In Argentina, HEV is not tested in blood banks and its control is a matter of debate. Our objective was to determine HEV serological and molecular prevalence in blood donors from Córdoba. Five hundred and forty-seven plasma samples from blood donors (229 women, 318 men; median age: 35 years), obtained between February and May 2016 (n = 147), 2019 (n = 200), and 2020 (n = 200) were analyzed. IgG and IgM anti-HEV detection were performed by ELISA, and RNA detection was carried out by real-time RT-PCR and nested-PCR. Statistical analyzes were performed using R3.6.3 (statistical significance of p <0.05). The global prevalence of anti-HEV IgG was 3.7% (19/547), being similar in all years: 2.05% in 2016 (3/147), 3.50% in 2019 (7/200) and 4.50% in 2020 (9/200) (p=0,47). A greater trend in HEV seroprevalence was observed in men than in women (4.72 vs 1.75%, p=0.06), and an increase with age (p=0,07), without statistical significance. Two positive samples for anti-HEV IgG were also IgM positive (2/19, 10.53%). RNA-HEV was detected in 1/547 (0.18%) samples, which corresponded to a 37-year-old male donor, without liver signs or symptoms or serological evidence of infection. The resulted seroprevalences were similar to those previously described in the general population, reporting the first molecular finding in blood donors from Argentina. The local molecular prevalence is within the range described (0.012% to 0.6%) in blood donors from other non-endemic countries, in which immunocompetent RNA-HEV positive donors without serological evidence of infection were identified, highlighting: 1) the existence of the potential risk of transfusion transmission, particularly important for immunosuppressed patients; 2) the detection of HEV-RNA as the best option for screening in blood banks, although this would imply a high cost (thus pooling could be an appropriate option for HEV screening); and 3) the importance of continue HEV hemovigilance.Resumen:  El virus de hepatitis E (HEV), causante de hepatitis aguda, puede progresar a hepatitis crónica en inmunosuprimidos. Se ha reportado transmisión por vía transfusional, siendo los portadores asintomáticos reservorios del virus y una potencial amenaza para la seguridad transfusional. En Argentina, el HEV no es testeado en bancos de sangre y su control es un tema de debate. Nuestro objetivo fue determinar la prevalencia serológica y molecular para HEV en donantes de sangre de Córdoba. Se estudiaron 547 muestras de plasma de donantes de sangre (229 mujeres, 318 hombres; mediana edad: 35 años), obtenidas entre febrero y mayo de 2016 (n=147), 2019 (n=200) y 2020 (n=200). Se realizó detección de IgG e IgM anti-HEV por ELISA, y de RNA mediante RT-PCR en tiempo real y nested-PCR. Se realizaron análisis estadísticos utilizando R3.6.3 (significancias estadísticas: p <0.05). La prevalencia global de IgG anti-HEV fue 3,47% (19/547) resultando similar en todos los años:  2,05% en 2016 (3/147), 3,50% en 2019 (7/200) y 4,50% en 2020 (9/200) (p=0,47). Se observó una tendencia mayor en hombres que en mujeres (4,72 vs 1,75%, p=0,06), y un aumento con la edad (p=0,07), sin significancia estadística. Dos muestras positivas para IgG anti-HEV resultaron IgM positivas (2/19, 10,53%). Se detectó RNA-HEV en 1/547 (0,18%) muestras, la cual correspondió a un donante masculino de 37 años, sin signos ni síntomas hepáticos ni evidencia serológica de infección.   Las seroprevalencias obtenidas fueron similares a las descriptas previamente en población general, reportando el primer hallazgo molecular en donantes de sangre de Argentina. La prevalencia molecular local se encuentra dentro del rango descripto (0,012% a 0,6%) en donantes de sangre de otros países no endémicos, en los que se identificaron donantes inmunocompetentes RNA-HEV positivos sin evidencia serológica de infección, destacando: 1) la existencia del potencial riesgo de transmisión transfusional, particularmente importante para inmunosuprimidos; 2) la detección de RNA-HEV como la mejor opción para el screening en bancos de sangre, aunque esto implicaría un elevado costo, por lo que el agrupamiento en pools podría ser una opción apropiada para el tamizaje de HEV; y 3) la importancia de continuar la hemovigilancia de HEV.

Heavy fermions and two loop electroweak corrections to b→s+γb\rightarrow s+\gamma

Applying effective Lagrangian method and on-shell scheme, we analyze the electroweak corrections to the rare decay $b\rightarrow s+\gamma$ from some special two loop diagrams in which a closed heavy fermion loop is attached to the virtual charged gauge bosons or Higgs. At the decoupling limit where the virtual fermions in inner loop are much heavier than the electroweak scale, we verify the final results satisfying the decoupling theorem explicitly when the interactions among Higgs and heavy fermions do not contain the nondecoupling couplings. Adopting the universal assumptions on the relevant couplings and mass spectrum of new physics, we find that the relative corrections from those two loop diagrams to the SM theoretical prediction on the branching ratio of $B\rightarrow X_{_s}\gamma$ can reach 5% as the energy scale of new physics $\Lambda_{_{\rm NP}}=200$ GeV.Comment: 30 pages,4 figure

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Abstract:  The study of the SARS-CoV-2 genome allows to evaluate its evolutionary pattern, identify mutations, lineages and variants that may have an impact on public health. Variants of concern (VOC) and variants of interest (VOI), which have different biological characteristics, have been identified worldwide. The objective of this work is to describe the lineages and variants of SARS-CoV-2 circulating in Córdoba using different strategies. Three strategies were implemented from positive SARS-CoV-2 RNA samples (Cts<30): 1)-whole genome sequencing (WGS) (ONT-MinION): 203 samples analysed from March 2020 to June 2021; 2)-partial sequencing of the Spike protein gene (Sanger): 54 samples analysed between February and April 2021 of travellers from abroad; and 3)-real time RT-PCR for detection of relevant VOC mutations (TaqMan™ SARS-CoV-2 Mutation Panel, Applied Biosystems): 816 samples analysed between May and June 2021.   Results were the following: 1)-circulation of 7 lineages with a greater predominance of B.1.1.33.3 (N3) (40.5%) and B.1.499 (38.8%), between March 2020 and January 2021; and circulation of 12 lineages with presence of VOC [P.1 (Gamma, 28.4%), B.1.1.7 (Alpha, 6.9%)] and VOI [C.37 (Lambda, 20.6%), B.1.427 (Epsilon, 10.8%), P2 (Zeta, 2.9%), B.1.526 (Iota, 2%)], between February and June 2021; 2)-presence of VOC Alpha (26.4%) and Gamma (17%), and samples compatible with VOI Epsilon and Zeta; 3)-presence of VOC Gamma (56%) and Alpha (11%), and other variants which could not be typified by this methodology. Results show the circulation of many SARS-CoV-2 lineages in Córdoba, which varied their distribution over time, according to the different introductions occurred, the population movement and the evolutionary advantages of some variants over others. In March 2021, the first VOC detections were realized in the province (Alpha and Gamma), being Gamma the one that mostly circulates at present. Although the WGS is the technique which provides more information, the other 2 strategies implemented were and are very useful tools for molecular epidemiological surveillance, obtaining the information in real time. Strategy 3 is a simpler, faster and more operative tool for molecular VOC screening.Resumen:  El estudio del genoma de SARS-CoV-2 permite evaluar su dinámica evolutiva, identificar mutaciones, linajes y variantes que puedan impactar en la salud pública. A nivel mundial se identificaron variantes de preocupación (VOC) y variantes de interés (VOI), que presentan características biológicas diferentes. El objetivo del trabajo es describir los linajes y variantes de SARS-CoV-2 circulantes en Córdoba mediante tres estrategias. Se implementaron 3 estrategias, a partir de muestras de RNA positivas para el virus (Cts<30): 1)-secuenciación de genoma completo (ONT-MinION): 203 muestras analizadas desde marzo 2020 a junio 2021; 2)-secuenciación de un fragmento genómico de la proteína S (Sanger): 54 muestras analizadas entre febrero y abril 2021 en viajeros provenientes del exterior; y 3)-PCR en tiempo real para detección de VOC (TaqMan™ SARS-CoV-2 Mutation Panel, Applied Biosystems): 816 muestras analizadas entre mayo y junio de 2021.       Los resultados fueron: 1)-circulación de siete linajes con mayor predominancia de B.1.1.33.3 (N3) (40,5%) y B.1.499 (38,8%), entre marzo 2020 y enero 2021; y circulación de 12 linajes con presencia de VOC [P.1 (Gamma, 28,4%), B.1.1.7 (Alpha, 6,9%)] y VOI [C.37 (Lambda, 20,6%), B.1.427 (Epsilon, 10,8%), P2 (Zeta, 2,9%), B.1.526 (Iota, 2%)], entre febrero y junio 2021; 2)-presencia de VOC Alpha (26,4%) y Gamma (17%), y muestras compatibles con las VOI Epsilon y Zeta (9,4%); 3)-presencia de VOC Gamma (56%) y Alpha (11%), y otras variantes no tipificables por esta metodología. Los resultados muestran circulación de diversos linajes de SARS-CoV-2 en Córdoba, que variaron su distribución a lo largo del tiempo, según las distintas introducciones ocurridas, el movimiento poblacional y las ventajas evolutivas de unos sobre otros. En marzo 2021 se realizaron las primeras detecciones de VOC en la provincia (Alpha y Gamma), siendo la variante Gamma la que circula mayoritariamente en la actualidad. Si bien la secuenciación del genoma completo es la técnica que mayor información brinda, las otras 2 estrategias implementadas fueron y son de gran utilidad para la vigilancia epidemiológica molecular, favoreciendo la obtención de información en tiempo real. La estrategia 3 resulta una herramienta más simple, rápida y con mayor capacidad operativa para el screening molecular de VOC.

Pericentromeric location of the telomeric DNA sequences on the European grayling chromosomes

The chromosomal characteristics, locations and variations of the C-band positive heterochromatin and telomeric DNA sequences were studied in the European grayling karyotype (Thymallus thymallus, Salmonidae) using conventional C-banding, endonucleases digestion banding, silver nitrate (AgNO3), chromomycin A(3) and 4',6-diamidino-2-phenylindole staining techniques as well as fluorescence in situ hybridization (FISH) and primed in situ labelling. Original data on the chromosomal distribution of segments resistant to AluI restriction endonuclease and identification of the C-banded heterochromatin presented here have been used to characterize the grayling karyotype polymorphism. Structural and length polymorphism of the chromosome 21 showing a conspicuous heterochromatin block adjacent to the centromere seems to be the result of the deletion and inversion. Two pairs of nuclear organizer regions (NOR)-bearing chromosomes were found to be polymorphic in size and displaying several distinct forms. FISH with telomeric peptide nucleic acid probe enabled recognition of the conservative telomeric DNA sequences. The karyotype of the thymallid fish is thought to experienced numerous pericentric inversions and internal telomeric sites (ITSs) observed at the pericentromeric regions of the six European grayling metacentric chromosomes are likely relics of the these rearrangements. None of the ITS sites matched either chromosome 21 or NOR bearing chromosomes.University of Warmia and Mazury in Olsztyn, Poland (0804.0809)info:eu-repo/semantics/publishedVersio