Springer Science and Business Media LLC

Feed contaminated with Salmonella spp. constitutes a risk of Salmonella infections in animals, and subsequently in the consumers of animal products. Salmonella are occasionally isolated from the feed factory environment and some clones of Salmonella persist in the factory environment for several years. One hypothesis is that biofilm formation facilitates persistence by protecting bacteria against environmental stress, e.g. disinfection. The aim of this study was to investigate the biofilm forming potential of Salmonella strains from feed- and fishmeal factories. The study included 111 Salmonella strains isolated from Norwegian feed and fish meal factories in the period 1991–2006 of serovar Agona, serovar Montevideo, serovar Senftenberg and serovar Typhimurium.

Significant differences were found between serovars regarding the abilities to form biofilm on polystyrene (microtiter plate assay) and in the air-liquid interface of nutrient broth (pellicle assay). Strains of serovar Agona and serovar Montevideo were good biofilm producers. In Norwegian factories, clones of these serovars have been observed to persist for several years. Most serovar Senftenberg clones appear to persist for a shorter period, and strains of this serovar were medium biofilm producers in our test systems. Strains of the serovar Typhimurium were relatively poor biofilm producers. Salmonella ser. Typhimurium clones have not been observed to persist even though this serovar is resident in Norwegian wild life. When classifying strains according to persistence or presumed non-persistence, persistent strains produced more biofilm than presumed non-persisting strains.

The results indicate a correlation between persistence and biofilm formation which suggests that biofilm forming ability may be an important factor for persistence of Salmonella in the factory environment.

Porcine reproductive and respiratory syndrome virus (PRRSV) is divided into a European and North American genotype. East European PRRSV isolates have been found to be of the European genotype, but form different subtypes. In the present study, PRRSV was isolated from a Belarusian farm with reproductive and respiratory failure and designated "Lena". Analyses revealed that Lena is a new East European subtype 3 PRRSV isolate. The main purpose of this investigation was to study the pathogenesis and antigenic characteristics of PRRSV (Lena).

Obvious clinical and virological differences were observed between the animals inoculated with a recent European subtype 1 PRRSV isolate (Belgium A) and animals inoculated with PRRSV (Lena). Three out of six pigs inoculated with PRRSV (Belgium A) had anorexia and low fever at 3, 4 and 5 days post-inoculation (dpi). High fever, anorexia and depression were prominent signs in most pigs inoculated with PRRSV (Lena) between 2 and 28 dpi. Four pigs out of ten died during the experiment. Arcanobacterium pyogenes was isolated from lungs of one animal that died, and Streptococcus suis was isolated from lungs of one animal that was euthanized. The difference in viral titres in sera from PRRSV (Belgium A) and PRRSV (Lena)-infected pigs was statistically significant (p < 0.05) at 7, 10, 14 and 21 dpi. The highest viral titres in sera ranged from 10^4.8 to 10^6.1 TCID₅₀/ml for PRRSV (Lena) whereas they ranged from 10^3.1 to 10^4.8 TCID₅₀/ml for PRRSV (Belgium A).

The replication of PRRSV (Lena) was further studied in depth. Viral titres ranged from 10^2.5 TCID₅₀/100 mg to 10^5.6 TCID₅₀/100 mg in nasal secretions between 3 and 14 dpi and from 10^2.8 TCID₅₀/100 mg to 10^4.6 TCID₅₀/100 mg in tonsillar scrapings between 3 and 21 dpi. High viral titres were detected in lungs (10^2.3-10^7.7 TCID₅₀/g tissue), tonsils (10^2.0-10^6.2 TCID₅₀/g tissue) and inguinal lymph nodes (10^2.2-10^6.6 TCID₅₀/g tissue) until 35, 28 and 35 dpi, respectively.

To examine the antigenic heterogeneity between the East European subtype 3 isolate Lena, the European subtype 1 strain Lelystad and the North American strain US5, sets of monospecific polyclonal antisera were tested in immunoperoxidase monolayer assays (IPMAs) with homologous and heterologous viral antigens. Heterologous antibody titres were significantly lower than homologous titres (p = 0.01-0.03) for antisera against PRRSV (Lena) at all sampling time points. For antisera against PRRSV (Lelystad) and PRRSV (US5), heterologous antibody titres were significantly lower than homologous titres at 14 and 21 dpi (p = 0.01-0.03) and at 10 and 14 dpi (p = 0.04), respectively.

Lena is a highly pathogenic East European subtype 3 PRRSV, which differs from European subtype 1 Lelystad and North American US5 strains at both the genetic and antigenic level.

In a previous study, it was demonstrated that high replication of Porcine circovirus 2 (PCV2) in a gnotobiotic pig was correlated with the absence of PCV2-neutralizing antibodies. The aim of the present study was to investigate if this correlation could also be found in SPF pigs in which PMWS was experimentally reproduced and in naturally PMWS-affected pigs.

When looking at the total anti-PCV2 antibody titres, PMWS-affected and healthy animals seroconverted at the same time point, and titres in PMWS-affected animals were only slightly lower compared to those in healthy animals. In healthy animals, the evolution of PCV2-neutralizing antibodies coincided with that of total antibodies. In PMWS-affected animals, neutralizing antibodies could either not be found (sera from field studies) or were detected in low titres between 7 and 14 DPI only (sera from experimentally inoculated SPF pigs). Differences were also found in the evolution of specific antibody isotypes titres against PCV2. In healthy pigs, IgM antibodies persisted until the end of the study, whereas in PMWS-affected pigs they quickly decreased or remained present at low titres. The mean titres of other antibody isotypes (IgG1, IgG2 and IgA), were slightly lower in PMWS-affected pigs compared to their healthy group mates at the end of each study.

This study describes important differences in the development of the humoral immune response between pigs that get subclinically infected with PCV2 and pigs that experience a high level of PCV2-replication which in 3 of 4 experiments led to the development of PMWS. These observations may contribute to a better understanding of the pathogenesis of a PCV2-infection.

Q fever, a worldwide zoonotic disease caused byCoxiella burnetii, is endemic in northern Spain where it has been reported as responsible for large series of human pneumonia cases and domestic ruminants' reproductive disorders. To investigate pathogen exposure among domestic ruminants in semi-extensive grazing systems in northern Spain, a serosurvey was carried out in 1,379 sheep (42 flocks), 626 beef cattle (46 herds) and 115 goats (11 herds). Serum antibodies were analysed by ELISA and positive samples were retested by Complement Fixation test (CFT) to detect recent infections.

ELISA anti-C. burnetiiantibody prevalence was slightly higher in sheep (11.8 ± 2.0%) than in goats (8.7 ± 5.9%) and beef cattle (6.7 ± 2.0%). Herd prevalence was 74% for ovine, 45% for goat and 43% for bovine. Twenty-one percent of sheep flocks, 27% of goat and 14% of cattle herds had aC. burnetiiseroprevalence ≥ 20%. Only 15 out of 214 ELISA-positive animals reacted positive by CFT. Age-associated seroprevalence differed between ruminant species with a general increasing pattern with age. No evidence of correlation between abortion history and seroprevalence rates was observed despite the known abortifacient nature ofC. burnetiiin domestic ruminants.

Results reported herein showed that sheep had the highest contact rate withC. burnetiiin the region but also that cattle and goats should not be neglected as part of the domestic cycle ofC. burnetii. This work reports basic epidemiologic patterns ofC. burnetiiin semi-extensive grazed domestic ruminants which, together with the relevant role ofC. burnetiias a zoonotic and abortifacient agent, makes these results to concern both Public and Animal Health Authorities.

Biểu hiện của protein prion tế bào là điều cần thiết cho sự phát triển của các bệnh não xốp lây truyền (TSEs), và ở cừu, độ nhạy di truyền với scrapie đã được liên kết với các đa hình gene PrP. Để kiểm tra mối liên kết giả thuyết giữa biểu hiện gene PrP và độ nhạy di truyền, mức độ mRNA PrP đã được đo bằng phương pháp RT-PCR thời gian thực trong sáu mô cừu của các động vật có kiểu gen khác nhau.

Trước khi phân tích biểu hiện gene PrP, tính ổn định của nhiều gene housekeeping (HK) đã được đánh giá để chọn ra những gene tốt nhất cho việc định lượng tương đối. Việc chuẩn hóa biểu hiện gene được thực hiện bằng cách sử dụng ít nhất ba gene HK để phát hiện những sự khác biệt nhỏ trong biểu hiện chính xác hơn so với việc sử dụng một gene đối chứng duy nhất. Phân tích độ ổn định biểu hiện của sáu gene HK cho thấy một sự biến động lớn liên quan đến mô phản ánh sự tồn tại của các yếu tố đặc hiệu với mô. Do đó, một tập hợp cụ thể các gene HK là cần thiết cho việc chuẩn hóa chính xác biểu hiện gene PrP trong mỗi mô. Những sự khác biệt thống kê trong mức độ mRNA PrP đã được chuẩn hóa được tìm thấy giữa các mô, với mức biểu hiện cao nhất ở obex, tiếp theo là ileum, hạch bạch huyết, lách, tiểu não và đại não. Một xu hướng về mức độ mRNA PrP cao hơn và độ nhạy di truyền đã được quan sát thấy ở hệ thần kinh trung ương. Tuy nhiên, các kết quả không ủng hộ giả thuyết rằng mức độ mRNA PrP thay đổi giữa các kiểu gen.

Các kết quả về biểu hiện gene PrP được trình bày ở đây cung cấp dữ liệu cơ bản quý giá cho các nghiên cứu trong tương lai về cơ chế bệnh sinh của scrapie. Mặt khác, các kết quả về dữ liệu ổn định của nhiều gene HK được báo cáo trong nghiên cứu này có thể rất hữu ích trong các nghiên cứu biểu hiện gene khác được thực hiện trên các mô cừu có liên quan này.