Developmental Dynamics of the Gut Virome in Tibetan Pigs at High Altitude: A Metagenomic Perspective across Age Groups.

Tibetan pig is a geographically isolated pig breed that inhabits high-altitude areas of the Qinghai-Tibetan plateau. At present, there is limited research on viral diseases in Tibetan pigs. This study provides a novel metagenomic exploration of the gut virome in Tibetan pigs (altitude ≈ 3000 m) across three critical developmental stages, including lactation, nursery, and fattening. The composition of viral communities in the Tibetan pig intestine, with a dominant presence of Microviridae phages observed across all stages of development, in combination with the previous literature, suggest that it may be associated with geographical locations with high altitude. Functional annotation of viral operational taxonomic units (vOTUs) highlights that, among the constantly increasing vOTUs groups, the adaptability of viruses to environmental stressors such as salt and heat indicates an evolutionary response to high-altitude conditions. It shows that the lactation group has more abundant viral auxiliary metabolic genes (vAMGs) than the nursery and fattening groups. During the nursery and fattening stages, this leaves only DNMT1 at a high level. which may be a contributing factor in promoting gut health. The study found that viruses preferentially adopt lytic lifestyles at all three developmental stages. These findings not only elucidate the dynamic interplay between the gut virome and host development, offering novel insights into the virome ecology of Tibetan pigs and their adaptation to high-altitude environments, but also provide a theoretical basis for further studies on pig production and epidemic prevention under extreme environmental conditions.

Bases-dependent Rapid Phylogenetic Clustering (Bd-RPC) enables precise and efficient phylogenetic estimation in viruses.

Understanding phylogenetic relationships among species is essential for many biological studies, which call for an accurate phylogenetic tree to understand major evolutionary transitions. The phylogenetic analyses present a major challenge in estimation accuracy and computational efficiency, especially recently facing a wave of severe emerging infectious disease outbreaks. Here, we introduced a novel, efficient framework called Bases-dependent Rapid Phylogenetic Clustering (Bd-RPC) for new sample placement for viruses. In this study, a brand-new recoding method called Frequency Vector Recoding was implemented to approximate the phylogenetic distance, and the Phylogenetic Simulated Annealing Search algorithm was developed to match the recoded distance matrix with the phylogenetic tree. Meanwhile, the indel (insertion/deletion) was heuristically introduced to foreign sequence recognition for the first time. Here, we compared the Bd-RPC with the recent placement software (PAGAN2, EPA-ng, TreeBeST) and evaluated it in Alphacoronavirus, Alphaherpesvirinae, and Betacoronavirus by using Split and Robinson-Foulds distances. The comparisons showed that Bd-RPC maintained the highest precision with great efficiency, demonstrating good performance in new sample placement on all three virus genera. Finally, a user-friendly website (http://www.bd-rpc.xyz) is available for users to classify new samples instantly and facilitate exploration of the phylogenetic research in viruses, and the Bd-RPC is available on GitHub (http://github.com/Bin-Ma/bd-rpc).

Resistin secreted by porcine alveolar macrophages leads to endothelial cell dysfunction during Haemophilus parasuis infection.

Haemophilus parasuis (H. parasuis) causes exudative inflammation, implying endothelial dysfunction during pathogen infection. However, so far, the molecular mechanism of endothelial dysfunction caused by H. parasuis has not been clarified. By using the transwell-based cell co-culture system, we demonstrate that knocking out resistin in porcine alveolar macrophages (PAMs) dramatically attenuated endothelial monolayer damage caused by H. parasuis. The resistin secreted by PAMs inhibited the expression of the tight junction proteins claudin-5 and occludin rather than the adherens junction protein VE-cadherin in co-cultured porcine aortic endothelial cells (PAECs). Furthermore, we demonstrate that resistin regulated claudin-5 and occludin expression and monolayer PAEC permeability in an LKB1/AMPK/mTOR pathway-dependent manner. Additionally, we reveal that the outer membrane lipoprotein gene lppA in H. parasuis induced resistin expression in PAMs, as deleting lppA reduced resistin expression in H. parasuis-infected PAMs, causing a significant change in LKB1/AMPK/mTOR pathway activity in co-cultured PAECs, thereby restoring tight junction protein levels and endothelial monolayer permeability. Thus, we postulate that the H. parasuis lppA gene enhances resistin production in PAMs, disrupting tight junctions in PAECs and causing endothelial barrier dysfunction. These findings elucidate the pathogenic mechanism of exudative inflammation caused by H. parasuis for the first time and provide a more profound angle of acute exudative inflammation caused by bacteria.

Molecular cloning and functional characterization of duck TYK2.

Tyrosine kinase 2 (TYK2), a member of Janus kinase family, has been identified as a crucial protein in signal transduction initiated by interferons or interleukins in mammals. However, the function of avian TYK2 in innate immune response remains largely unknown. In this study, the full-length duck TYK2 (duTYK2) cDNA was cloned for the first time, which encoded a putative protein of 1187 amino acid residues and showed the high sequence similarity with bald eagle, crested ibis, and white-tailed tropicbird TYK2s. The duTYK2 was widely expressed in all examined tissues of healthy ducks and showed diffuse cytoplasmic localization in duck embryo fibroblasts (DEFs). Overexpression of duTYK2 significantly enhanced ISRE promoter activity and induced the expression of viperin, PKR, 2',5'-OAS, Mx and ZAP in DEFs. The C-terminal kinase domain of duTYK2 is essential for duTYK2-mediated ISRE promoter activation. Furthermore, knockdown of duTYK2 dramatically decreased duck Tembusu virus (DTMUV)-, duck enteritis virus (DEV)-, poly(I:C)- or poly(dA:dT)-induced ISRE promoter activation. Additionally, duTYK2 expression exhibited antiviral activity against DTMUV. These results indicated that duTYK2 played a critical role in duck antiviral innate immunity.