Effect of sow mass vaccination against Mycoplasma hyopneumoniae on the humoral immune response of newborn piglets.

Pneumonia caused by Mycoplasma (M.) hyopneumoniae is one of the major respiratory diseases in swine production. Commercial vaccines for M. hyopneumoniae are widely used in weaned piglets to reduce lung lesions and clinical signs in the downstream flow; however, no information regarding the effect of mass immunization of the breeding herd is available. The aim of this work was to evaluate a mass vaccination protocol for M. hyopneumoniae on the humoral response of sows and their offspring 24 h post-partum (trial registration number 40156). A total of 52 sows from two different farms (13 primiparous and 13 multiparous sows on each farm), one with mass vaccination (MVF) and one without mass vaccination against M. hyopneumoniae (control farm (CF)) were enrolled in this study. Five piglets from each litter were selected, resulting in 260 piglets. Blood was collected from sows and piglets 24 h post-partum for M. hyopneumoniae antibody detection by ELISA. The results showed that primiparous sows from MVF had higher antibody titers compared to multiparous sows of the same farm, and multiparous and primiparous sows from the CF. Similar results were evidenced in their offspring. The findings of this study suggest that mass vaccination results in a more robust serologic response on primiparous sows, which could be the main target of vaccination strategies for the breeding herd.

Chicken parvovirus viral loads in cloacal swabs from malabsorption syndrome-affected and healthy broilers.

Chicken parvovirus (ChPV) has been associated with malabsorption syndrome (MAS) in broilers. However, the participation of this virus in such syndrome is unclear, since it may be detected in diseased and healthy chickens. In the course of these studies, it was argued whether ChPV genome loads might be correlated to the occurrence of MAS. To check such a hypothesis, a SYBR green-based quantitative polymerase chain reaction was developed to detect and quantify ChPV genomes. Cloacal swabs from 68 broilers with MAS and 59 from healthy animals were collected from different poultry farms. Genomes of ChPV were detected in all samples, regardless of their health status. However, viral genome loads in MAS-affected broilers were significantly higher (1 × 105 genome copies per 100 ng DNA) than in healthy animals (1.3 × 103 GC/100 ng DNA). These findings indicate that there is an association between high ChPV genome loads and the occurrence of MAS in broilers.

Ungulate copiparvovirus 1 (bovine parvovirus 2): characterization of a new genotype and associated viremia in different bovine age groups.

A novel bovine parvovirus 2 (BPV2) genotype comprising 5394 nt was identified by next generation sequencing from sera of healthy cattle at different age groups farmed in the state of Rio Grande do Sul, Brazil. The genome organization of new BPV2 genotype retains the two ORFs typical of members of the Parvovirinae with 86.4 % of overall nucleotide sequence identities in comparison to other members of the subfamily. Phylogenetic analysis revealed similar clustering with two previously described bovine BPV2 within the genus Copiparvovirus. No significant differences (P ≥ 0.05) were detected in the distribution of BPV2 infection in cattle at different age groups. This is the third complete or near complete genome sequence of BPV2 reported to date and may contribute to a better understanding of the biology of copiparvoviruses and its interactions with the host.

Report of outbreaks of classical scrapie in Dorper sheep and associated prion protein gene polymorphisms in affected flocks.

Scrapie is an infectious neurodegenerative disease affecting sheep and goats, related with conformational alteration of an isoform of the prion protein that leads to deposition and aggregation in the host's central nervous system. Occurrence of the natural disease can be influenced by host genetic factors, such as a single nucleotide polymorphism of the prion protein gene. This study reports three scrapie-affected Dorper flocks located on three different farms in Brazil. The objective of this study was to analyze these three flocks using scrapie diagnostics, combining histology, immunohistochemistry, genotyping, and western blot assays. For immunohistochemistry, 192 sheep were selected and 308 sheep blood samples were taken for genotyping. A total of 22 sheep were scrapie positive by immunohistochemistry. Of these, four presented clinical signs and had scrapie immunoreactivity at the obex in western blot assays. The sheep without clinical signs were positive in lymphoid organs, such as the third eyelid and rectal mucosa. The major genotypes found on the flocks were ARQ/ARQ, ARQ/ARR, and ARQ/VRQ for codons 136, 154, and 171. Most of the sheep were considered to be at moderate to high risk, based on risk groups for developing scrapie. Some blood samples were sequenced, and polymorphisms were identified in other codons, such as 127, 142, and 143. Our data demonstrate the importance of preclinical scrapie diagnosis in Brazilian sheep, as most of the affected sheep showed no clinical signs, and emphasize the relevance of genotyping other Dorper sheep to determine the genotypic profile of the breed.