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6 recordsLinked to original sources
PubMed2026

Rumen DNA virome plasticity and viral metabolic potential are associated with seasonal adaptation in grazing yak and cattle on the Qinghai-Tibet Plateau.

BACKGROUND: As a diverse and abundant component of the rumen ecosystem, viruses interact with other microorganisms and are thought to influence microbial metabolism and host productivity. However, how the rumen virome responds to seasonal fluctuations in extreme environments remains poorly understood. Here, metagenomic analyses were used to investigate temporal dynamics of viral diversity, functional potential, and virus-host associations in the rumen virome of yak and cattle on the Qinghai-Tibet Plateau across warm and cold seasons. RESULTS: Rumen viral communities exhibited pronounced seasonal variation in both yaks and cattle, with higher alpha diversity observed during the cold season than in the warm season. Across seasons, the yak rumen virome showed greater alpha diversity and community stability than that of cattle. In total, 27,353 temperate and 31,976 virulent viral operational taxonomic units (vOTUs) were identified, predominantly belonging to the class Caudoviricetes. These viruses were linked to microbial hosts spanning 24 bacterial and 8 archaeal phyla, with Bacteroidota and Bacillota representing the dominant lineages. Virus-host associations were more numerous in the cold season and showed distinct host-specific patterns between yaks and cattle. Cold-season virome exhibited reduced diversity of anti-defense genes and enrichment of auxiliary metabolic genes (AMGs) associated with fatty acid metabolism and hemicellulose degradation. Notably, greater divergence between yaks and cattle was observed during the cold season: the yak rumen virome was enriched in pathways related to amino acid, lipid, and energy metabolism, as well as cellulose-degrading CAZyme families, whereas the cattle rumen virome showed enrichment in general carbohydrate metabolism and replication and repair processes. CONCLUSION: Seasonal plasticity of rumen DNA virome and pronounced interspecific divergence between yaks and cattle provide insight into their distinct microbial processes in the harsh environment of the Qinghai-Tibet Plateau. These findings suggest that the rumen DNA virome exhibits complex ecological and functional responses to seasonal variation and may be associated with host-microbiome interactions and nutrient utilization under environmental stress. This study highlights the ecological relevance of rumen viral genomes in understanding virus-microbiome interactions, microbial adaptation, and nutrient utilization in high-altitude ruminants.

Auxiliary metabolic genes↗
PubMed2026

Molecular Characterization of Listeria monocytogenes Isolated from Retail Yak Meat in Nyingchi, Xizang, China.

Listeria monocytogenes is a Gram-positive zoonotic pathogen responsible for listeriosis, a severe foodborne disease with high mortality in humans and animals. This study aimed to investigate the molecular epidemiology and genomic characteristics of L. monocytogenes isolated from raw yak meat in Nyingchi, Xizang, China. A total of 231 yak-related samples were collected in Nyingchi, consisting of 214 retail raw yak meat samples, 14 farm environmental samples, and 3 nearby water source samples. L. monocytogenes isolates were identified and characterized using culture-based methods, PCR serotyping, and whole-genome sequencing (WGS). Bioinformatic analyses were performed for virulence, antimicrobial resistance, and functional gene annotation using KEGG and COG databases. The overall contamination rate of Lm was 13.08% (28/214) for retail raw yak meat samples, whereas no isolates were recovered from 14 farm environmental samples (0.00%, 0/14) and 3 nearby water source samples (0.00%, 0/3). The serotypes of isolates were 1/2a (9/28, 32.14%), 1/2b (7/28, 25.00%), and 1/2c (12/28, 42.86%). These 28 isolates exhibited varied antimicrobial resistance profiles, with universal resistance to trimethoprim-sulfamethoxazole, high resistance to erythromycin and clindamycin, and low resistance to vancomycin. MLST analysis revealed seven sequence types (STs): ST9 (12/28, 42.86%), ST619 (6/28, 21.43%), ST8 (6/28, 21.43%), ST7 (1/28, 3.57%), ST87 (1/28, 3.57%), ST121 (1/28, 3.57%), ST297 (1/28, 3.57%). ST619 isolates harbored multiple virulence genes, including those located on Listeria pathogenicity islands LIPI-1, LIPI-3, and LIPI-4, indicating high genomic potential for virulence. Representative isolate Y2 (ST619) possessed a 3,009,858 bp genome with 3036 coding genes, four genomic islands, and two prophages. Functional annotation revealed enrichment of genes involved in carbohydrate transport and metabolism and amino acid biosynthesis pathways. Our findings provide the first genomic insight into L. monocytogenes contamination in yak meat from Nyingchi, Xizang, China, highlighting the urgent need to strengthen food safety monitoring and hygiene management in this region.

Listeria monocytogenes↗
PubMed2026

Comparative analysis of gut microbiota in yaks under different feeding management strategies during cold seasons.

Yaks (Bos grunniens) are crucial for the livelihoods of pastoral communities in cold regions, where feed scarcity during the cold season poses challenges to their health and productivity, underscoring the necessity of understanding how dietary management influences the gut microbiota. In this study, 24 yak steers matched for body weight and health status were randomly allocated to four groups: natural grazing or indoor feeding with roughage-to-concentrate ratios of 50:50, 70:30, or 90:10. Fecal samples were collected for 16S rDNA sequencing and subsequent functional prediction of the microbiota. The results showed that Firmicutes and Bacteroidetes were the dominant phyla across all groups, and UCG-005 and Rikenellaceae_RC9_gut_group were the predominant genera. Concentrate supplementation during the cold season significantly enhanced microbial richness and diversity, with the 70:30 ratio exerting the most pronounced beneficial effects on microbiota structure and key taxa enrichment. These findings highlight the critical role of dietary management in shaping the yak gut microbiota during cold seasons and suggest that the 70:30 ratio optimally improves microbial community structure, thereby promoting yak health and productivity under harsh climatic conditions. Future research should explore the long-term implications of such dietary strategies.

Animals↗
PubMed1975

Recurring hemolytic anemia, babesiasis, and influenza A viruses in a yak at low altitude in Nepal.

Episodes of hemolysis and leukocytosis which were associated with Babesia bigemina followed each of 3 challenge exposures to influenza A viruses. It is possible that viral infection altered the immunologic host-parasite equilibrium. Acute thrombocytopenia and rouleaux formation were also observed. Death, attributed to liver flukes, occurred 168 days after the yak was transferred from high to low altitude. A 2nd yak died of foot-and-mouth disease, thus supporting the Nepali belief that yaks will not survive at the lower altitudes of Kathmandu.

Altitude↗
PubMed2026

Metagenomic analysis of the midgut microbiome in Dermacentor abaensis ticks at different feeding states.

Ticks are blood-sucking ectoparasites of humans and animals, ranking second only to mosquitoes as vectors of diseases. Dermacentor abaensis is distributed in Sichuan, Qinghai, and Gansu, China. Because D. abaensis harbors several pathogens, it poses a threat to public health and livestock production. However, the midgut microbiota of D. abaensis at distinct feeding states remains poorly characterized. Adult D. abaensis ticks at various feeding states were collected from yaks in Gansu Province, China. Genomic DNA was extracted from midguts and midgut contents of unfed, partially fed, and fully engorged female D. abaensis. A metagenomic sequencing approach was employed to profile the midgut microflora among three groups. A total of 83 phyla, 908 genera, and 1857 species were annotated across the three groups. At the phylum level, Pseudomonadota, Mucoromycota, and Ascomycota were the most abundant. At the species level, common bacterial species such as Klebsiella pneumoniae and Anaplasma phagocytophilum, alongside viruses and eukaryotes, were detected in all three groups. Unique microorganisms were also observed in each group: unfed (n = 305), partially fed (n = 59), and fully engorged (n = 20). Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis suggested that the D. abaensis microbiome contains a relatively high abundance of functional genes involved in lipid and amino acid metabolism across the three different feeding states. These findings indicate that while core microbial taxa are shared in the midgut of female D. abaensis, observable trends suggest variations in microbial diversity and composition as blood-feeding progresses. The present study provides a descriptive baseline of the midgut microbial composition of D. abaensis, which may inform future studies on tick biology and the ecology of tick-borne pathogens.

Animals↗