Exploratory study on the impact of <i>Ganoderma australe</i> extract on gut microbiota and immune gene expression in honey bees exposed to <i>Vairimorpha ceranae</i>

by Sarah Zuern, Bella Romero, Carlos Spichiger, Leandro Ortiz, Alejandro Jerez, Esteban Basoalto, Max Emil Schön, Sigisfredo Garnica

The microsporidium Vairimorpha (Nosema) ceranae is an emerging threat to honey bees (Apis mellifera), known to disrupt gut microbiota and suppress immune responses, potentially contributing to colony losses. Fungal extracts have recently gained interest as sources of bioactive compounds with antimicrobial and immunomodulatory potential. In this study, we explored the effects of different dietary supplements—sugar syrup, HiveAlive™, and a novel Ganoderma australe extract (GanoBee)—on gut bacterial composition and immune-related gene expression in honey bees subjected to experimental exposure to V. ceranae 1 x 10⁴ spores per bee. The GanoBee diet altered the gut microbiota, notably reducing the relative abundance of Rhizobiaceae (Bartonella apis) and increasing Frischella compared to other treatments. While alpha diversity was not significantly affected by diet or exposure to V. ceranae, beta diversity differed significantly in bees fed with GanoBee. Additionally, the expression of the antimicrobial peptide genes abaecin and hymenoptaecin was elevated in both exposed and unexposed bees fed with GanoBee, depending on the sampling day. However, the establishment of V. ceranae infection appeared limited, likely due to low spore viability, and mortality in control bees was higher than expected. The low Vairimorpha ceranae infection levels observed in this study are likely attributable to reduced spore viability caused by storage conditions and/or suboptimal environmental conditions within the laboratory cages. Post hoc analyses indicated that the high viscosity of GanoBee-supplemented diets likely contributed to the elevated bee mortality observed, underscoring a critical limitation of the experimental design related to diet formulation and delivery method. These physical factors complicate the interpretation of treatment efficacy and highlight the importance of optimizing feeding protocols to avoid confounding effects. Despite these constraints, GanoBee demonstrated promising potential as a modulator of gut microbiota composition and immune-related gene expression, supporting the need for further research under improved and carefully controlled experimental conditions.

<i>In vivo</i> and <i>in vitro</i> susceptibility and inflammatory response of postnatal mouse cortical neurons and glial cells to zika virus infection

by María-Angélica Calderón-Peláez, Myriam L. Velandia-Romero, Jaime E. Castellanos

Zika virus (ZIKV) poses a significant threat to neural tissue, causing substantial damage to unborn children exposed to the virus in utero, with consequences that can manifest even after birth, despite being born with a normal head circumference. Regardless of the extensive research, the interactions between ZIKV and the nervous system cells remain insufficiently understood, particularly regarding how neuronal responses influence broader inflammatory and viral dynamics especially in postnatal stages of development. This study evaluated the susceptibility to ZIKV infection, viral replication, immune response, and survival of neurons, astrocytes and microglial cells during postnatal developmental stages, using both in vivo and in vitro mice models. In vivo, a non-lethal but extensive infection of neurons and microglia was shown. The infection caused a robust but controlled immune response with elevated levels of MCP-1, TNF-α, and IL-6, that prevented severe neuronal damage. In vitro, neurons exhibited high susceptibility to ZIKV, with elevated levels of pro-inflammatory cytokines and IFN-β, indicating a strong inflammatory response. In contrast, astrocytes and microglia displayed varied responses, contributing to a pro-inflammatory feedback loop. These findings offer critical insights into the cellular dynamics of ZIKV infection, enhancing our understanding of its effects during postnatal nervous system development. By clarifying the interactions between ZIKV and neuronal cell types, this study deepens the comprehension of the virus’s pathophysiology and its broader implications for neurodevelopmental outcomes, extending beyond the well-documented association with microcephaly.