Evaluation of the Antiviral Activity of Propolis from Native Bees (<i>Plebeia frontalis</i>) against Canine Distemper Virus

Propolis is a natural substance made from resins collected from trees and plants, and which bees combine with pollen, wax, and their own enzymes. It has a complex chemical composition that varies with the harvest season, vegetation type, bee species, and geographical region. Thanks to its components, it has valuable biological properties such as antifungal, antibacterial, anticancer, antiviral, and immunomodulatory activity. For this study, a sample of propolis harvested in April 2019 was used, which came from a bee native to Mexico (Plebeia frontalis) in whose geographical environment there are seven other native species. Canine distemper virus is an RNA virus that causes a systemic infection with high fatality rates in guests without protective immunity. In this work, the antiviral effect of Plebeia frontalis propolis on canine distemper virus was tested, administering it one hour before and simultaneously to infection. The antiviral effect was evaluated by determining cellular viability with the MTT assay. The results obtained show that this propolis has a statistically significant antiviral effect on both treatments, although it is slightly better when applied one hour before viral infection, so we can recommend it as an antiviral treatment in both domestic animals and human beings. There are currently few studies of the antiviral effect of propolis, this being the first study of a melliponium propolis in veterinary medicine.

Evaluation of Changes in Actin Filaments of RK13 Cells Infected with <i>Malassezia pachydermatis</i>

Background: Malassezia pachydermatis is the main causative agent of canine otitis and also of a myriad of dermatological problems in companion animals;its interaction mechanisms with host cells are still unclear. Objectives: To establish an in vitro infection model of M. pachydermatis-exposed RK13 cells in order to evaluate cell morphological changes as well as changes in the structure of actin filaments. Methods: Cultures of RK13 cells were infected with M. pachydermatis, alterations caused by the yeast were evaluated by optical and fluorescence microscopy. Results: M. pachydermatis adheres itself to the cell and produces the formation of multiple agglomerates that cause changes in cell morphology, formation of cell aggregates in overlays, presence of syncytia and destruction of cell culture structure. The damaged cells presented changes in the actin filaments consisting of thickening of the cell cortex and loss of stress fibers. On the other hand, the formation of perinuclear actin rings in the yeasts was observed. Conclusions: An in vitro infection model was established with M. pachydermatis and alterations in cell morphology were observed consisting of changes in the structure of the actin filaments, overgrowth of the cells and the presence of syncytia.

Determination of mRNA Expression of Typical Proteins of Tight Junctions in the Intestinal Mucosa of Broilers (<i>Gallus gallus domesticus</i>)

Tight junctions are mainly formed by two types of proteins;claudins and occludin, both of which are fundamental to maintain the integrity and barrier function of the intestinal epithelium. This barrier function allows for the absorption of nutrients, mainly by transcytosis;however, in birds, 90% of the substances are absorbed by paracellular mechanisms. Despite this, claudins present in the different parts of the intestinal tract of adult chickens are not known, much less their functional role. This study aimed to determine the presence of mRNA of claudins 1, 2, 3, 5, 10, 12, 16 and occludin, in the different regions of the intestine (duodenum, jejunum, ileum, cecum, and rectum) in chickens (Gallus gallus domesticus) through RT-PCR. To meet this goal, 7 weeks old roosters destined for slaughter and chicken embryos of 16 days of incubation (positive control) were used. For all the processed samples, amplicons of the expected size were obtained;claudin 1 (662 pb), claudin 2 (162 pb), claudin 3 (185 pb), claudin 5 (224 pb), claudin 10 (687 pb), claudin 12 (738 pb), claudin 16 (191 pb) and occludin (430 pb). To corroborate these findings, obtained amplicons were sequenced and, subsequently, a basic alignment was performed on the NCBI, obtaining a correlation of 100% with the original sequences in all analyzed samples. To our knowledge, the present work represents the first written report regarding the presence of mRNA of the main proteins involved in tight junction formation throughout the intestinal tract of domestic chickens of 7 weeks of age. These findings will allow elucidating the specific function of each of the reported proteins in the process of paracellular absorption in chickens.