Low-molecular-weight chitosan relieves enterotoxigenic Escherichia coli-induced growth retardation in weaned pigs

The objective of the present study was to evaluate the effects of low-molecular-weight chitosan (LMWC) on the growth performance, immune responses and intestinal health of weaned pigs challenged by enterotoxigenic Escherichia coli (ETEC). A total of 32 weaned pigs were randomly allocated to four treatments: non-challenged (fed with basal diet), ETEC-challenged (fed with basal diet) and ETEC-challenged plus 50 or 100 mg/kg LMWC supplementation, respectively. After 11 days feeding, the non-challenged pigs were infused with sterilised Luria–Bertani culture, while the remaining pigs were infused with 2.6 × 10¹¹ colony-forming units of ETEC. At 3 days post-challenge, all pigs were administered d-xylose at 0.1 g/kg body weight. One hour later, blood samples were obtained, and the pigs then euthanised to collect intestinal samples. Data showed that only 100 mg/kg LMWC supplementation attenuated (P < 0.05) the average daily gain reduction caused by ETEC. Furthermore, besides the decreased (P < 0.05) serum tumour necrosis factor-α and immunoglobulin (Ig) G concentrations detected in ETEC-challenged pigs supplemented with LMWC at 50 or 100 mg/kg, the higher dose (100 mg/kg) also decreased (P < 0.05) the serum IgM concentration and increased (P < 0.05) the villus height and villus height-to-crypt depth ratio in both the jejunum and ileum, and the sucrase activity in the ileal mucosa. Moreover, LMWC supplementation (50 or 100 mg/kg) in ETEC-challenged pigs elevated (P < 0.05) the mRNA levels of jejunal mucosal peptide transporter 1 and ileal mucosal peptide transporter 1, divalent metal transporter 1 and zinc transporter 1, and decreased (P < 0.05) the ileal and caecal E. coli abundances, while 100 mg/kg LMWC additionally elevated (P < 0.05) the ileal Bacillus abundance, and caecal and colonic Bifidobacterium abundances. These results suggest that LMWC helps alleviate ETEC-induced growth retardation in weaned pigs, which could be associated with the inhibition of the immune responses and improved intestinal health.     

Does porcine circovirus type 3 (PCV3) interfere with porcine circovirus type 2 (PCV2) vaccine efficacy?

PCV2 is globally spread pathogen involved in a number of diseases (PCVD). Commonly used vaccines against PCV2 are proved to be highly efficacious. The role of recently discovered PCV3 for pig health and interference with PCV2 remains unknown. The study performed on serum samples from seven farms vaccinated against PCV2 and four non‐vaccinated showed very low prevalence of PCV2 viremia in the former (3 out of 106 positive serum pools) and high prevalence of PCV2 viremia in the latter (35 out of 60 positive pools). Mean log₁₀ PCV2 genome equivalents were lower in vaccinated farms (4.8 ± 0.6 log₁₀ copies/ml) than in non‐vaccinated farms (6.3 ± 1.3 log₁₀ copies/ml). PCV3 was detected in 31 out of 106 and 12 out of 60 serum pools from vaccinated and non‐vaccinated farms, respectively. Mean log₁₀ PCV3 genome equivalents were significantly (p < 0.05) lower in vaccinated farms (3.9 ± 0.8 log₁₀ copies/ml) than in non‐vaccinated farms (4.4 ± 0.6 log₁₀ copies/ml). Concurrent PCV2 and PCV3 infection was rare and found only in 1 out of 529 and 4 out of 292 individual serum samples from vaccinated and non‐vaccinated farms, respectively. Our results showed lack of impact of PCV3 circulation on PCV2 vaccine efficacy. On the other hand, intensive PCV2 circulation and high viremia detected in non‐vaccinated farms did not seem to increase the level of PCV3 infection.     

First report of Neospora caninum infection in pigs in China

Neospora caninum is a protozoan parasite which can infect many mammals and birds with a worldwide distribution. However, no molecular data are available about the occurrence of N. caninum in pigs. In this study, the serological and molecular prevalence of N. caninum infection in farmed pigs were investigated in Hunan province, China, between January 2017 and December 2018. A total of 1,500 serum samples collected from 10 herds in Hunan province were evaluated using a competitive‐inhibition enzyme‐linked immunoassay assay (cELISA). The overall seroprevalence of N. caninum in the examined pigs was 1.9%. The seroprevalence of N. caninum ranged from 0.3% to 4.6% among different regions in Hunan province of China (p < .05). DNA was extracted from brain samples, and the Nc‐5 gene and ITS‐1 region were amplified and then sequenced. Three (0.5%) of the examined 600 brain tissues were found to contain N. caninum DNA. Our phylogenetic analyses indicated that N. caninum samples were classified into two distinct groups. Although the prevalence is low within the pig groups investigated, our results revealed the emergence of N. caninum infection in pigs in China. The finding of the present study provides molecular evidence that the pigs are the natural intermediate host of N. caninum and may have major epidemiological importance.     

Successful reproduction of adenoviral gizzard erosion in 20-week-old SPF layer-type chickens and efficacious prophylaxis due to live vaccination with an apathogenic fowl adenovirus serotype 1 strain (CELO)

Recently, outbreaks of adenoviral gizzard erosion (AGE) have been documented in pullets and layers housed free range and in enriched cage systems characterized by increased mortality and a negative impact on egg production. In the present study the pathogenicity of a fowl adenovirus serotype 1 (FAdV-1) field strain as well as the aetiological role of a FAdV-8a strain, both isolated from AGE affected pullets, were investigated in vivo in 20-week-old specific-pathogen-free (SPF) layer-type chickens. Furthermore, the efficacy of a single (week 17) and double (week 14 and 17) application of a live vaccine consisting of an apathogenic FAdV-1 (CELO strain) against challenge with virulent FAdV-1 was investigated.For the first time, AGE was successfully reproduced in adult birds after oral infection of 20-week-old SPF birds with a virulent FAdV-1 field isolate, characterized by pathological changes of the gizzard from 7 days post challenge onwards. In addition, a negative impact of the FAdV-1 infection on the development of the reproductive tract was observed. Thus, confirming the pathogenicity and aetiological role of FAdV-1 in the development of AGE and economic losses due to AGE in layers. In contrast, no pathological changes were observed in birds infected with FAdV-8a.Independent of a single or double application of the live FAdV-1 vaccine strain CELO, no gross pathological changes were observed in gizzards post challenge with the virulent FAdV-1, indicating that complete protection of layers against horizontal induction of AGE was achieved. Nonetheless, virulent FAdV-1 was detected in cloacal swabs and gizzards in both vaccinated groups post challenge determined by the application of an amplification refractory mutation system quantitative PCR used to differentiate between vaccine and challenge strains.     

Porcine Epidemic Diarrhea Virus among Farmed Pigs,Ukraine

An outbreak of porcine epidemic diarrhea occurred in the summer of 2014 in Ukraine, severely affecting piglets <10 days of age; the mortality rate approached 100%. Full genome sequencing showed the virus to be closely related to strains reported from North America, showing a sequence identity of up to 99.8%.     

川芎嗪对离体豚鼠气道平滑肌的效应及机制研究

目的：探讨川芎嗪( ligustrazine,LIG)对离体豚鼠气道平滑肌( airway smooth muscle,ASM)的效应及机制。方法取正常豚鼠支气管,制作成气管螺旋条,随机分成LIG组、LIG+普萘洛尔组、LIG+阿托品组、LIG+硝苯地平组、LIG+格列苯脲组、对照组。分别观察ASM在静息张力下以及组胺所致的高张力下,各组不同LIG浓度对ASM的效应并比较各组间ASM舒张率。结果(1) LIG对离体豚鼠ASM静息张力以及组胺所致的高张力均具有舒张作用。(2)离体豚鼠ASM在静息张力下,与LIG组比较,LIG+普萘洛尔组在LIG浓度10-7~10-6．5 mol/L时,舒张作用明显受到拮抗( P <0．05)。 LIG +阿托品组、LIG+格列苯脲组在LIG浓度10-7．5~10-3 mol/L时,舒张作用没有明显差别(P>0．05)。 LIG+硝苯地平组在LIG浓度10-6~10-4 mol/L时,舒张作用明显加强( P<0．05)。(3)离体豚鼠ASM在组胺所致的高张力下,与LIG组比较,LIG+普萘洛尔组在LIG浓度10-6.5~10-5 mol/L时,舒张作用明显受到拮抗( P<0．05);LIG+阿托品组、LIG+格列苯脲组在LIG浓度10-8~10-3 mol/L时,舒张作用没有明显差别( P>0．05);LIG+硝苯地平组在LIG浓度10-6.5~10-5 mol/L时,舒张作用明显加强(P<0．05)。结论 LIG可对离体豚鼠ASM静息张力以及组胺所致的高张力产生明显的舒张作用,其效应的产生可能与竞争性激动β2受体以及抑制Ca2+内流有关,这为临床应用川芎嗪治疗支气管哮喘提供了理论依据。