Reactivation of hepatitis B virus with immune-escape mutations after ocrelizumab treatment for multiple sclerosis

Ocrelizumab is an anti-CD20 monoclonal antibody for the treatment of multiple sclerosis (MS) that is closely related to rituximab. We describe a case of hepatitis B virus (HBV) reactivation in an MS patient with resolved HBV infection receiving ocrelizumab. HBV reactivation was monitored with HBV-DNA and HBV surface antigen periodic assessment. Anti-HBV treatment with entecavir was started after HBV-DNA detection. Ocrelizumab can reactivate viral replication in patients with resolved HBV infection. HBV reactivation monitoring seems an effective and safe option for the management of these patients. More studies are needed to assess the optimal management of HBV reactivation in MS patients on ocrelizumab treatment

Removal of cardiac AL-amyloid with positive remodeling of cardiomyocytes and of restrictive cardiomyopathy

Herein, we describe histological mobilization of light chain cardiac amyloid documented by sequential left ventricular endomyocardial biopsies. These findings were associated with positive remodelling of cardiomyocytes and of restrictive cardiomyopathy resulting from 14 courses of chemotherapy over 17 years of time. Histological and ultrastructural findings of light chain cardiac amyloid removal led to increase in cardiomyocyte dimension and electrocardiogram voltages, reduction of biventricular wall thickness with improvement of left ventricular diastolic function, and NYHA class shifting from III to I

A method for semi-field rearing of Varroa destructor (Acari: Varroidae) to obtain mites of controlled age and specific life cycle

Varroa destructor is one of the most devastating ectoparasites of the honey bee, Apis mellifera, worldwide. Given that V. destructor has very low survivability and exhibits no successful reproduction away from their natural environment and host and that the availability of mites for experimental purposes is limited by seasonality, several protocols of mite rearing under laboratory conditions have been developed. However, only one of these rearing systems has been able to yield a fertile second generation with a low mite survival. The aim of this study was to develop a semi-field rearing method to obtain mites of known age and life cycle that can be maintained through several generations. We registered and compared survival and reproductive parameters of mites of controlled age during four generations (P, F1, F2, F3) and evidenced no significant differences between these mite groups for these life-history traits. With present results we demonstrate that it is possible to successfully produce a third generation of mites under semi-field conditions. This study brings useful information about key conditions for the proper reproduction of mites in a controlled rearing system and provides a potential standardized method for V. destructor research, especially for host-parasite interaction experiments.Fil: Muntaabski, Irina. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo | Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo.; ArgentinaFil: Russo, Romina Maria. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo | Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo.; ArgentinaFil: Liendo, María Clara. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo | Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo.; ArgentinaFil: Landi, Lucas. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Recursos Biológicos; ArgentinaFil: Lanzavecchia, Silvia Beatriz. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo | Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo.; ArgentinaFil: Scannapieco, Alejandra Carla. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo | Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo.; Argentin

Infiltration of conduction tissue is a major cause of electrical instability in cardiac amyloidosis

Abstract: Background: Pathology of conduction tissue (CT) and relative arrhythmias in living subjects with cardiac amyloid have never been reported. Aims: Reporting CT pathology and its arrhythmic correlations in human cardiac amyloidosis. Methods and Results: In 17 out of 45 cardiac amyloid patients, a left ventricular endomyocardial biopsy included conduction tissue sections. It was identified by Aschoff-Monckeberg histologic criteria and positive immunostaining for HCN4. The degree of conduction tissue infiltration was defined as mild when ≤ 30%, moderate when 30-70% and severe when > 70% cell area was replaced. Conduction tissue infiltration was correlated with ventricular arrhythmias, maximal wall thickness and type of amyloid protein. Mild involvement was observed in 5 cases, moderate in 3 and severe in 9. Involvement was associated with a parallel infiltration of conduction tissue artery. Conduction infiltration correlated with severity of arrhythmias (Spearman rho=0.8, p <0.001). In particular, major ventricular tachyarrhythmias requiring pharmacologic treatment or ICD implantation occurred in 7 patients with severe, 1 patient with moderate and none with mild conduction tissue infiltration. Pacemaker implantation was required in 3 patients with complete conduction section replacement. No significant correlation was observed between the degree of conduction infiltration and age, cardiac wall thickness or type of amyloid protein. Conclusion: Amyloid-associated cardiac arrhythmias correlate with extent of conduction tissue infiltration. Its involvement is independent from type and severity of amyloidosis, suggesting a variable affinity of amyloid protein to conduction tissue

Pemphigus-associated cardiomyopathy: report of autoimmune myocarditis and review of literature

Pemphigus is a rare disease characterized by bullous lesions of the skin and mucous membranes. The aetiology is autoimmune and related to the formation of IgG autoantibodies against desmogleins, which are structural proteins of desmosomes that ensure the stability of contacts between cells. Cardiac involvement in patients with pemphigus is poorly documented. We report the data in the literature on this topic and a case of pemphigus-associated autoimmune myocarditis with damage of intercalated disc responding to immunosuppressive therapy. The occurrence of cardiomyopathy with left ventricular dysfunction in patients affected by pemphigus should be appropriately screened with endomyocardial biopsy as it could be the myocardial extension of a potentially reversible autoimmune disorder

Reactivation of hepatitis B virus with immune-escape mutations after ocrelizumab treatment for multiple sclerosis

Ocrelizumab is an anti-CD20 monoclonal antibody for the treatment of multiple sclerosis (MS) that is closely related to rituximab. We describe a case of hepatitis B virus (HBV) reactivation in an MS patient with resolved HBV infection receiving ocrelizumab. HBV reactivation was monitored with HBV-DNA and HBV surface antigen periodic assessment. Anti-HBV treatment with entecavir was started after HBV-DNA detection. Ocrelizumab can reactivate viral replication in patients with resolved HBV infection. HBV reactivation monitoring seems an effective and safe option for the management of these patients. More studies are needed to assess the optimal management of HBV reactivation in MS patients on ocrelizumab treatment

Grooming Behavior in Naturally Varroa-Resistant Apis mellifera Colonies From North-Central Argentina

The Western honey bee, Apis mellifera, is an important species in providing honey and pollination services globally. The mite Varroa destructor is the major threat to A. mellifera, and it is associated with the severe colony winter mortality reported in recent decades. However, Varroa mite tolerant or resistant populations of A. mellifera have been detected around the world. A proposed mechanism responsible for limiting mite population growth in the colonies is grooming behavior, the physical removal and injury of mites from the adult bee bodies by individual workers or by their nest-mates. This behavioral strategy has been poorly studied in V. destructor-resistant colonies worldwide, especially in honey bee populations of European origin. In Argentina, honey bee stocks showing survival without mite treatment have been reported. In the present study, European-derived A. mellifera populations established in the Transition Chaco eco-region (Santa Fe province), with a subtropical climate, were characterized at the colony level. A honey bee stock showing natural Varroa-resistance (M) was compared to a Varroa-susceptible stock (C) for parameters of colony status (colony strength, percentage of Varroa infestation in adults and brood, hygienic behavior) and for indirect measures of grooming (percentage of fallen mites and damaged mites). M colonies showed lower phoretic and brood infestation and higher hygienic behavior in early autumn, and higher survival and population strength after wintering, in comparison with C colonies. The mean percentages of fallen mites and of damaged mites, and the injury to mites were higher in M than in C colonies. Our results suggest that, by modulating the parasitization dynamics in colonies, grooming behavior would be associated with the higher survival of Varroa-resistant stock. This study sheds light on how honey bee colonies can adaptively respond to mite pressure by modeling their behavior to resist Varroosis and provides evidence for grooming as an emerging factor evolving by natural selection. Percentage of damaged mites appears to be a reliable measure to enhance this behavior in honey bee colonies by selective breeding. Finally, the importance of improving and protecting locally adapted honey bee populations with natural Varroa resistance for regional apiculture is discussed.Fil: Russo, Romina Maria. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo | Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo.; ArgentinaFil: Liendo, María Clara. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo | Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo.; ArgentinaFil: Landi, Lucas. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Recursos Biológicos; ArgentinaFil: Pietronave, Hernán Pablo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Reconquista; ArgentinaFil: Merke, Julieta. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; ArgentinaFil: Fain, Hernan. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Reconquista; ArgentinaFil: Muntaabski, Irina. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo | Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo.; ArgentinaFil: Palacio, Maria Alejandra. Universidad Nacional de Mar del Plata; ArgentinaFil: Rodríguez, Ana Graciela. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Hilario Ascasubi; ArgentinaFil: Lanzavecchia, Silvia Beatriz. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo | Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo.; ArgentinaFil: Scannapieco, Alejandra Carla. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion En Ciencias Veterinarias y Agronomicas. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo | Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Agrobiotecnologia y Biologia Molecular. Grupo Vinculado Instituto de Genetica "ewald A. Favret" Al Iabimo.; Argentin

Gut bacteriome analysis of Anastrepha fraterculus sp. 1 during the early steps of laboratory colonization

Microbial communities associated to insect species are involved in essential biological functions such as host nutrition, reproduction and survivability. Main factors have been described as modulators of gut bacterial community, such as diet, habit, developmental stage and taxonomy of the host. The present work focuses on the complex changes that gut microbial communities go through when wild insects are introduced to artificial rearing conditions. Specifically, we analyzed the effect of the laboratory colonization on the richness and diversity of the gut bacteriome hosted by the fruit fly pest Anastrepha fraterculus sp. 1. Bacterial profiles were studied by amplicon sequencing of the 16S rRNA V3–V4 hypervariable region in gut samples of males and females, in teneral (1-day-old, unfed) and post-teneral (15-day-old, fed) flies. A total of 3,147,665 sequence reads were obtained and 32 bacterial operational taxonomic units (OTUs) were identified. Proteobacteria was the most abundant phylum (93.3% of the total reads) and, Wolbachia and Enterobacter were the most represented taxa at the genus level (29.9% and 27.7%, respectively, of the total read counts). Wild and laboratory flies showed highly significant differences in the relative abundances of bacteria. The analysis of the core bacteriome showed the presence of five OTUs in all samples grouped by origin, while nine and five OTUs were exclusively detected in laboratory and wild flies, respectively. Irrespective of fly origin or sex, a dominant presence of Wolbachia was observed in teneral flies, whereas Enterobacter was highly abundant in post-teneral individuals. We evidenced significant differences in bacterial richness and diversity among generations under laboratory colonization (F0, F1, F3 and F6) and compared to laboratory and wild flies, displaying also differential patterns between teneral and post-teneral flies. Laboratory and wild A. fraterculus sp. 1 harbor different gut bacterial communities. Laboratory colonization has an important effect on the microbiota, most likely associated to the combined effects of insect physiology and environmental conditions (e.g., diet and colony management).Instituto de GenéticaFil: Salgueiro, Julieta. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética. Laboratorio de Genética de Insectos de Importancia Económica; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pimper, Lidia Elena. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética. Laboratorio de Genética de Insectos de Importancia Económica; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Segura, Diego Fernando. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética. Laboratorio de Genética de Insectos de Importancia Económica; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Milla, Fabian Horacio. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética. Laboratorio de Genética de Insectos de Importancia Económica; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Russo, Romina María. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética. Laboratorio de Genética de Insectos de Importancia Económica; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Asimakis, Elias D. University of Patras. Department of Environmental Engineering; GreciaFil: Stathopoulou, Panagiota. University of Patras. Department of Environmental Engineering; GreciaFil: Bourtzis, Kostas. Vienna International Centre. Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture. Insect Pest Control Laboratory; AustriaFil: Cladera, Jorge Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética. Laboratorio de Genética de Insectos de Importancia Económica; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tsiamis, George. University of Patras. Department of Environmental Engineering; GreciaFil: Lanzavecchia, Silvia Beatriz. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética "Ewald A. Favret". Laboratorio de Genética de Insectos de Importancia Económica; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Morphometric and genetic characterization as tools for selection of Apis mellifera (Hymenoptera: Apidae) stocks in an area of natural hybridization in Argentina

Beekeepers around the world select bees’ characteristics that facilitate and favor production. In regions where hybridization among lineages is taking place, this selection is a challenge, given that these regions are “natural laboratories”, where the action of evolutionary processes of a population or species occurs in real time. A natural honeybee (Apis mellifera) hybrid zone exists in Argentina between 28° and 35° South, where Africanized (AHB) and European (EHB) populations converge. In this zone, beekeepers use selected genetic resources of European origin mostly, since the local Africanized bees show a higher defensive behavior, which is not desirable for management. Although EHB colonies have many advantages for honey production, they are not fully adapted to the subtropical climate and are susceptible to certain parasitosis such as varroosis. In addition, both AHB and EHB mate in drone congregation areas (DCAs), where males and virgin queens fly to meet, resulting in variability in the desired characteristics. In this study, we explored the degree of hybridization within a DCA and its reference apiary, located in the province of Entre Ríos, by applying two complementary techniques. First, morphotypes with different degrees of hybridization between European and African subspecies were observed in the reference apiary, indicating a high sensitivity of this morphometric approach to detect hybridization in these populations. Second, a genetic analysis revealed haplotypes of both origins for drones in DCAs, with a higher prevalence of European haplotypes, while all the colonies from the reference apiary exhibited European haplotypes. Overall, our results are in line with the strong impact that commercial beekeeping has on the genetics of DCAs. We show how wing morphometry may be used to monitor hybridization between European and African subspecies, a tool that may be evaluated in other regions of the world where hybridization occurs.Instituto de GenéticaFil: Litvinoff, Leonardo. Reinas del Litoral SRL; ArgentinaFil: Menescardi, Francisco. Reinas del Litoral SRL; ArgentinaFil: Porrini, Leonardo. Instituto de Investigaciones en Producción, Sanidad y Ambiente (CONICET-UNSAM). Centro de Investigación en Abejas Sociales; ArgentinaFil: Porrini, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Russo, Romina Maria. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética; ArgentinaFil: Russo, Romina Maria. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; ArgentinaFil: Russo, Romina Maria. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Liendo, María Clara. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética; ArgentinaFil: Liendo, María Clara. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; ArgentinaFil: Liendo, María Clara. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Nucci, Alejandro. Instituto de Investigaciones en Producción, Sanidad y Ambiente (CONICET-UNSAM). Centro de Investigación en Abejas Sociales; ArgentinaFil: Nucci, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lusarreta, Esteban. Instituto de Investigaciones en Producción, Sanidad y Ambiente (CONICET-UNSAM). Centro de Investigación en Abejas Sociales; ArgentinaFil: Lusarreta, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ventura, Rocio. Instituto de Investigaciones en Producción, Sanidad y Ambiente (CONICET-UNSAM). Centro de Investigación en Abejas Sociales; ArgentinaFil: Ventura, Rocio. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Espasadin, Luna. Fundación Miguel Lillo. Instituto de Entomología; ArgentinaFil: Monmany-Garzia, A. Carolina. Universidad Nacional de Tucumán. Instituto de Ecología Regional; ArgentinaFil: Monmany-Garzia, A. Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Scannapieco, Alejandra Carla. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética; ArgentinaFil: Scannapieco, Alejandra Carla. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular; ArgentinaFil: Scannapieco, Alejandra Carla. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Galindo Cardona, Alberto. Fundación Miguel Lillo. Instituto de Entomología; ArgentinaFil: Galindo Cardona, Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Age-performance and intensity of grooming behavior toward Varroa destructor in resistant and susceptible Apis mellifera colonies

Grooming behavior confers resistance to honey bees against Varroa destructor, being of interest to social immunity studies and breeding programs. The objective of this study was to characterize at the individual level the grooming behavior of mite-resistant (R) and susceptible (S) A. mellifera stocks from Argentina. Assays were performed in experimental arenas by applying two treatments to nurse bees: (1) placing a V. destructor mite on the bee’s thorax and (2) touching the bee with a paintbrush. Grooming reactions were recorded on bees from both stocks at the ages of 6, 10, and 14 days after emergence. R bees exhibited lower time of first response against the mite, performed more cleaning attempts, and used all their legs with a higher probability compared to S bees. The same pattern was evident when younger and older bees from the R stock were compared. The results demonstrate that bee age and genetic origin are critical factors of grooming behavior in honey bees.Fil: Russo, Romina Maria. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Agrobiotecnología y Biología Molecular. Grupo Vinculado Instituto de Genética "Ewald A. Favret" al Iabimo | Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Agrobiotecnología y Biología Molecular. Grupo Vinculado Instituto de Genética "Ewald A. Favret" al Iabimo; ArgentinaFil: Landi, Lucas. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Recursos Biológicos; ArgentinaFil: Muntaabski, Irina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Agrobiotecnología y Biología Molecular. Grupo Vinculado Instituto de Genética "Ewald A. Favret" al Iabimo | Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Agrobiotecnología y Biología Molecular. Grupo Vinculado Instituto de Genética "Ewald A. Favret" al Iabimo; ArgentinaFil: Liendo, María Clara. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Agrobiotecnología y Biología Molecular. Grupo Vinculado Instituto de Genética "Ewald A. Favret" al Iabimo | Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Agrobiotecnología y Biología Molecular. Grupo Vinculado Instituto de Genética "Ewald A. Favret" al Iabimo; ArgentinaFil: Pietronave, Hernán Pablo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Reconquista; ArgentinaFil: Merke, Julieta. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; ArgentinaFil: Rodríguez, Graciela A.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Hilario Ascasubi; ArgentinaFil: Palacio, María A.. Universidad Nacional de Mar del Plata; Argentina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Basilio, Alicia Mabel. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Animal. Cátedra de Avicultura, Cunicultura y Apicultura; ArgentinaFil: Lanzavecchia, Silvia Beatriz. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Agrobiotecnología y Biología Molecular. Grupo Vinculado Instituto de Genética "Ewald A. Favret" al Iabimo | Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Agrobiotecnología y Biología Molecular. Grupo Vinculado Instituto de Genética "Ewald A. Favret" al Iabimo; ArgentinaFil: Scannapieco, Alejandra Carla. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Agrobiotecnología y Biología Molecular. Grupo Vinculado Instituto de Genética "Ewald A. Favret" al Iabimo | Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Agrobiotecnología y Biología Molecular. Grupo Vinculado Instituto de Genética "Ewald A. Favret" al Iabimo; Argentin