Genetic and pathogenic characterizations of a naturally occurring reassortant and homologous recombinant strain of the classical infectious bursal disease virus re-emerging in chickens in southern China.

Infectious bursal disease (IBD) classical virus strain (cIBDV) can cause morbidity and mortality in young chickens with severe long-term immunosuppression. However, since the emergence and widespread prevalence of very virulent strain (vvIBDV) in China from 1991, reports of cIBDV have become rare. A novel reassortant and recombinant strain GXYL211225 (genotype A1aB1a) with segment A originating from the classical strain (A1a) and segment B from the attenuated vaccine strain (B1a) was characterized in the study. Notably, segment A resulted from recombination between the cIBDV strains 150127-0.2 and Faragher52-70, expressing as a backbone from 150127-0.2, where a fragment located at the position of nucleotide (nt) 519-1 410 was replaced by the corresponding region of Faragher52-70. The infection of GXYL211225 caused mortality in SPF chicken embryos, despite lacking the critical amino acid (aa) residues 253H, 279 N and 284A associated with the cellular tropism, and induced significant cytopathic effect (CPE) on a wide range of cells, confirming its natural cell-adapted character. Furthermore, the challenge experiment of GXYL211225 was performed on the commercial Three-yellow chickens of 4-week-old, and with the vvIBDV HLJ-0504-like strain NN1172 and the novel variant (nv) IBDV strain QZ191002 as the comparison. All the challenged birds experienced reduced body-weight gain. QZ191002 infected birds showed no obvious clinical symptoms or mortality, while those of NN1172 and GXYL211225 showed typical IBD symptoms and resulted in 20% (2/10) and 10% (1/10) of mortality rates, respectively. At 7 days post-challenge (dpc), the damages of bursal of Fabricius (BF) varied among groups, with NN1172 causing the most severe lesions, followed by GXYL211225, and then QZ191002. It was also found that the pathogenicity was correlated positively with the viral load, aligning with the histopathological severity in BF. The study confirms the rapid and diverse evolution of the re-emerged classical strains in the field and emphasizes the need to monitor the changes of IBDV on both the genetic and pathogenic aspects for the effective control of the disease.

Effects of prolonged fluoride exposure on innate immunity, intestinal mechanical, and immune barriers in mice.

The aim of this study is to explore the effects of fluoride on the innate immunity, intestinal mechanical barrier, and immune barrier of C57BL/6 mice, as well as to analyze the degree of structural and tissue damage, providing reference data for related research. Mice were randomly divided into four groups and then treated with 0 mg/L (control), 50 mg/L, 100 mg/L, 125 mg/L sodium fluoride solution, respectively, for 120 days. Histological technique, ELISA, MTT colorimetry methods were used to detect and analyze the effects of different concentrations of fluoride on the intestinal morphology, mechanical barrier and the immune functions and innate immunity of mice. The results showed that compared with the control group, the villi were injured in different degrees of the three fluoride groups, the number of goblet cells, the protein expression levels of connexin ZO-1, Claudin-1 and Occludin, the content of Diamine Oxidase (DAO), endotoxin (ET) and D-lactic acid (D-LA), the activity of natural killer cell (NK cells), the number and percentage of neutrophils and erythrocytes, the phagocytic rate of neutrophils, and the rate of C3bR rosette (which is formed by the adhesion of C3b receptors on the red blood cell membrane to complement sensitized yeast) and IC rosette (which is formed by the adhesion of C3b molecules in the immunecomplex adhered to the red blood cell membrane to non sensitized yeast) of red blood cells, the content of interlenkin 1 beta (IL-1ß) and interlenkin 8 (IL-8), the number and percentage of lymphocytes decreased with the increasing of fluoride concentration. In addition, the content of the Immunoglobulin A (sIgA) showed a trend of increase at first and then decrease in salivary gland and jejunum. It is concluded that excessive intake of fluoride for a long time has a certain damage effect on the intestinal tract, leading to an increase in the permeability of the intestinal tract, thereby destroying the mechanical and immune barrier function of the intestinal tract.

Comparative study of the histomorphological structure of the small intestine of Lonchura striata and Copsychus saularis / Estudio comparativo de la estructura histomorfológica del intestino delgado de Lonchura striata y Copsychus saularis

SUMMARY: Six Lonchura striata and six Copsychus saularis birds were selected in this study, morphological index of the small intestine was measured by quantitative biology and image analysis. The changes of goblet cells and Na+/K+ATPase were detected by AB-PAS staining and ELISA to inform the different mechanisms of the digestion and absorption of nutrients between the Lonchura striata and Copsychus saularis. The villus height, crypt depth and muscle thickness of each segment of small intestine of Lonchura striata were smaller than those of Copsychus saularis, and the difference of ileum muscle thickness was significant. In addition, the ileum villus height/crypt depth (VH/CD) value of Lonchura striata was significantly less than that of Copsychus saularis. The number of goblet cells in duodenum and jejunum of Lonchura striata and Copsychus saularis had no significant difference, but the number of goblet cells in ileum of Copsychus saularis was significantly larger than that of Lonchura striata. The vitality of Na+/K+-ATPase in different intestinal segments of the Lonchura striata and the Copsychus saularis was different. The vitality of Na+/K+-ATPase in the Lonchura striata was significantly higher than that of the Copsychus saularis. It can be concluded that the digestion and absorption capacity of Copsychus saularis and Lonchura striata are significantly different, and the reason may be due to their different diets and intestinal floras.

RESUMEN: En este estudio se seleccionaron seis aves Lonchura striata y seis Copsychus saularis, a las cuales se midió mediante biología cuantitativa y análisis de imágenes el índice morfológico del intestino delgado. Los cambios de las células caliciformes y Na+/K+ATPasa se detectaron mediante tinción AB- PAS y ELISA para informar los diferentes mecanismos de digestión y absorción de nutrientes entre Lonchura striata y Copsychus saularis. La altura de las vellosidades, la profundidad de las criptas y el grosor del músculo de cada segmento del intestino delgado de Lonchura striata fueron menores que los de Copsychus saularis, y se observó una diferencia significativa en el grosor de la músculatura del íleon. Además, el valor de la altura de la vellosidad del íleon/profundidad de la cripta (VH/CD) de Lonchura striata fue significativamente menor que el de Copsychus saularis. En el número de células caliciformes del duodeno y del yeyuno de Lonchura striata y Copsychus saularis no hubo una diferencia significativa, pero el número de células caliciformes en el íleon de Copsychus saularis fue significativamente mayor que el de Lonchura striata. Hubo diferencias en la vitalidad de Na+/K+-ATPasa en diferentes segmentos intestinales de Lonchura striata y Copsychus saularis. La vitalidad de Na+/K+-ATPasa en Lonchura striata fue significativamente mayor que la de Copsychus saularis. Se puede concluir que la capacidad de digestión y absorción de Copsychus saularis y Lonchura striata son significativamente diferentes, posiblemente debido a sus distintas dietas y floras intestinales.