BMC Veterinary Research最新文献

This research evaluated the efficacy of mixed Bacillus strains probiotic supplements in mitigating acute thermal-induced stress in Nile tilapia (Oreochromis niloticus). Three experimental fish groups involved 135 Nile tilapia (49 ± 2 g); one control (no added probiotics), 0.5, and 1% of selected Bacillus strains (B. subtilis, B. licheniformis, and B. pumilus) for 58 days. After the feeding period, growth parameters, immunological parameters, stress biochemical markers, and antioxidant parameters in addition to genes related to stress and histopathological changes in fish, were assessed; subsequently subjected to heat shock at 36 ± 0.5 ◦C for 2 h. Before the heat challenge, our results exhibited a marked increase in the growth efficacy (P < 0.05), lower marked serum levels of triglycerides and cholesterol, and tissue malondialdehyde (MDA) levels along with significantly increased superoxide dismutase (SOD) and catalase (CAT) enzymes activity in fish-fed Bacillus probiotic at 0.5% concerning the control group (P < 0.05). There were no significant changes in the serum levels of glucose, cortisol, lactate, phagocytic activity, respiratory burst (ROS), total immunoglobulin Ig, alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), total protein, albumin, globulin, uric acid, urea, creatinine, as well as HSP70, GST, and GPx mRNA expression in most of the probiotic groups compared to the control group (P > 0.05). When Nile tilapia was exposed to heat stress, supplementation with Bacillus probiotic in the diet significantly decreased most of the indices related to serum biochemical (ALT (P < 0.01; P < 0.001), AST (P < 0.01), LDH (P < 0.01), urea (P < 0.05), and creatinine (P < 0.01)), triglycerides (P < 0.001; (P < 0.01)), cholesterol (P < 0.01; (P < 0.05)), glucose (P < 0.001), and cortisol (P < 0.01; (P < 0.05)), with tissue oxidative stress MDA levels (P < 0.05), and HSP70 mRNA expression (P < 0.01; P < 0.001), aligned with the stressed control group. In addition, a notable upsurge in the total protein, albumin, globulin, phagocytic and ROS activities, and total Ig, as well as the enzymatic antioxidant ability (SOD, CAT) (P < 0.01), with GST and GPx mRNA expression (P < 0.05; P < 0.01), were shown in fish-fed Bacillus spp. post-exposure compared with the stressed control group. Besides, no histopathological alterations were revealed in the spleen and brain of fish pre- and post-heat exposure. According to our findings, diet supplementation of Bacillus species has the potential to combat the suppressive effects of heat shock in Nile tilapia.

Background: Streptococcus agalactiae (Group B streptococcus, GBS) induces a serious infection that can harm not only aquatic life but also humans and other animals. In a fish farm in southern Egypt, Nile tilapia (Oreochromis niloticus) has developed an epidemic with clinical symptoms resembling piscine streptococcosis.

Results: Initial microscopic inspection of the affected fish brain and kidney indicated the presence of Gram-positive cocci. S. agalactiae was effectively isolated and identified using nucleotide homology of the 16S rRNA and species-specific PCR. The partial 16S rRNA sequence was deposited in the GenBank database at the NCBI and given the accession number MW599202. Genotyping using RAPD analysis indicated that the isolates in the present study belonged to the same genotypes and had the same origin. The challenge test, via immersion (9.2 × 10⁷, 9.2 × 10⁶, and 9.2 × 10⁵ CFU/ml for 1 h) or intraperitoneal injection (4.6 × 10⁷, 4.6 × 10⁶, and 4.6 × 10⁵ CFU/fish), elicited clinical symptoms resembling those of naturally infected fish with a mortality rate as high as 80%. The ability to create a biofilm as one of the pathogen virulence factors was verified. Zinc oxide nanoparticles and the ethanolic leaf extracts of nine medicinal plants demonstrated considerable antibacterial activities against the tested S. agalactiae strain with low minimum bactericidal concentrations (MBC) and minimum inhibitory concentrations (MIC). The ethanolic leaf extracts from Lantana camara and Aberia caffra showed potent antibacterial activity with MBC values of 0.24 and 0.485 mg/ml, and MIC values of 0.12 & 0.24 mg/ml, respectively.

Conclusion: This study isolated S. agalactiae from O. niloticus mortalities in a fish farm in Assiut, Egypt. The pathogen persists in fish environments and can escape through biofilm formation, suggesting it cannot be easily eliminated. However, promising findings were obtained with in vitro control employing zinc oxide nanoparticles and medicinal plant extracts. Nevertheless further in vivo research is needed.

Background: Coronaviruses (CoVs) represent a serious threat to human health and have become a major transmissible, endemic, and causative pathogen in humans; they represent a major health concern, given their ability to cause infectious diseases. Bats are natural hosts for diverse viruses. Many transmission events of CoVs and identification of multiple novel CoVs in bats has increased attention towards their capacity to serve as hosts for zoonotic viruses.

Results: In this study, 61 bats from Yunnan Province were analyzed, identifying seven CoVs, including three α- and two β-CoVs with full-genome sequences. Among the five identified alpha-CoVs, four belong to the Decacovirus subgenus and one to the Minunacovirus subgenus. Two beta-CoVs were also identified, both belonging to the Sarbecovirus subgenus.The genetic structures revealed similarities to known strains such as HKU10 and SARS-CoV-2, along with novel findings such as the Minunacovirus subgenus CoV YJ3c/f and unique ORF patterns. Our results demonstrated that strain JCC9 has a unique recombination pattern and shows a higher binding affinity to civet and pangolin ACE2 receptors, then the HpJC8xc strain transmits and recombines between hosts (bats), indicating a potential risk of crossing the interspecies barrier and infecting other animals.

Conclusions: The CoVs detected in the bats studied in this research exhibit high diversity. Genomic analysis revealed that CoVs in bats undergo frequent recombination events. Furthermore, recombination patterns and evolutionary analyses suggest that alpha-CoVs are more prone to cross-species transmission across different bat families/genera, whereas beta-CoVs demonstrate host specificity and tend to co-evolve with their bat hosts.Our finding suggest that bats, as hosts of CoVs, be constantly monitored to prevent outbreaks of new infections caused by viruses passing across interspecies barriers, and consequently, viral diseases in humans or livestock.

Erysipelas still causes large economic losses to pig industry. Maternal immunity is critical to prevent erysipelas in young animals, thus, intensive vaccination protocols or practices focused on the improvement of the maternally derived immunity could provide substantial benefits. The present study evaluates potential changes in antibodies levels in sows and their offspring using two types of tests (commercial ELISA, Ingenasa or rSpaA415 ELISA) when two different vaccination programs (before farrowing or after farrowing) against Erysipelothrix rhusiopathiae were applied to sows from Iberian (A) or conventional Large White-Landrace (B) pig farms. The results showed a statistical correlation between titers found in sows and their one-week old piglets in both tests. The overall mean of (log) antibody titers in farm B measured by the commercial ELISA test was significantly higher in pre-farrowing vaccinated sows compared to the post-farrowing vaccine protocol (p = 0.0278). Additionally, using the rSpaA415 ELISA test, the overall mean of (log) antibody titers was significantly higher in pre-farrowing sows (p = 0.0056) compared to sows following post-farrowing vaccine protocol (p = 0.0003) or non- vaccinated sows. None of the above-mentioned differences were found in farm A. The overall mean of (log) antibody titers in piglets from the pre-farrowing vaccination protocol was significantly higher than piglets from the post-farrowing vaccination protocol in farm A (p = 0.0059; rSpaA415 ELISA) and farm B (p = 0.0168 and p = 0.0098 for the commercial and rSpaA415 ELISA data, respectively). Additionally, higher proportion of piglets from pre-farrowing vaccinated sows remained seropositive during the post-weaning period (days 42 to 84) compared to piglets from non-vaccinated or post-farrowing vaccinated groups in both farms A and B.

Background: Telocytes (TCs) is a novel type of interstitial cells in many mammals organs, which participate in the organizational metabolism, mechanical support, immunomodulation and other aspects. The aim of this study was to explore the organizational chemical characteristics of TCs in pituitary gland and their changes in cryptorchid yaks.

Methods: Transmission electron microscopy (TEM), toluidine blue staining, immunofluorescence, qRT-PCR, and Western blotting may enable us to understand TCs distribution characteristics and biological functions.

Result: TEM confirmed the presence of TCs in the pituitary gland with small bodies and moniliform telopodes (Tps). The Tps extending out from the cell body to the peri-sinusoidal vessels spaces, the number of Tps is closely related to the morphology of the nucleus. The most obvious changes of TCs in the pituitary gland of cryptorchid yaks is the Tps are relatively shorter and decreased secretory vesicles. H.E. and toluidine blue staining revealed that TCs not only distributed between the sinusoidal blood vessels and the glandular cell clusters, but also present on the surface of vascular endothelial cells. The co-expression of TCs biomarkers, such as Vimentin/CD34, CD117/CD34 and α-SMA/CD34, were evaluated by immunofluorescence to further determine the phenotypic characteristics of TCs. Besides, we analyzed the mRNA and protein expression of these biomarkers to determine the characteristics of TCs changes and possible biological roles. Both the mRNA and protein expression of CD117 were significantly higher in the pituitary gland of cryptorchid yaks than in the normal (p < 0.01), the protein expression of CD34 in the cryptorchid yaks was significantly higher than the normal (p < 0.01). There were no significant difference in mRNA expression of Vimentin and α-SMA (p>0.05), while the protein expression were significantly increased in the normal yaks (p < 0.05).

Conclusions: In summary, this study reports for the first time that the biological characteristics of TCs in yak pituitary gland. Although there is no significant change in the distribution characteristics, the changes in biological features of TCs in cryptorchid yaks are clear, suggesting that TCs participated in alteration in the local microenvironment of the pituitary gland. Therefore, our study provides clues for further investigating the role of TCs in the pituitary gland during the occurrence of cryptorchidism in yaks.

Background: Fish gut microbiota undergo dynamic changes under the influence of many factors and play an important role in the nutrition, immunity and development in fish. Although common carp (Cyprinus carpio L.) is an economically important freshwater fish, there are few reports on its gut microbiota changes at different early developmental stages. In the present study, the gut microbiota of common carp during the early developmental stages and its correlation with the feed and pond water flora were studied using the Illumina MiSeq sequencing platform.

Results: The results showed that the gut microbiota of common carp underwent continuous and mild changes over the development process, and the pond water environment might provide bacterial resources and have a certain influence on the changes in the gut microbiota of common carp. However, host selection pressure played a more important role in shaping the gut microbiota. Although the gut microbiota was affected by many factors, the presence of core microbiota indicated that some bacterial species adapt to the gut microenvironment of common carp and played a role in its growth process.

Conclusions: The dynamic changes of gut microbiota of carp in early development stage were related to the feed, water environment and host selection. The results of this study provide a theoretical basis for healthy farming and disease prevention of common carp.

Background: Recently, efforts like crossbreeding, strain crossing, and inbred hybridization have been performed to improve productive performance in native chickens. This experiment was carried out to evaluate the effects of crossbreeding on the improvement of the productivity of a native chicken. The White Leghorn exotic chicken (WL) as dam line and the Marandi indigenous chicken (MA) as sire line were used to generate the crossbreds (MA × WL). Body weight and egg production traits were measured in the three groups.

Results: There are significant performance differences between WL and MA, with WL exhibiting superior body weight and egg production compared to MA (P < 0.05). Crossbreeding between WL and MA significantly improved most traits, with MA × WL outperforming MA. Negative heterosis was observed for body weight showing similarities between MA and MA × WL. Notably, MA × WL showed a closer resemblance to WL than MA in hen-day egg production at 40 and 44 weeks (P < 0.05).

Conclusions: The results derived from this study show that the economic performance of native chickens can be enhanced through crossbreeding with exotic chickens. Using the crossbred chickens in rural areas can be more efficient than the native chickens. In addition, the resilience of the native chickens to the local environment can be transmitted genetically to the crossbred which should be investigated in further studies.