Experimental Airborne Transmission of Porcine Postweaning Multisystemic Wasting Syndrome

The objective of these studies was to investigate if porcine postweaning multisystemic wasting syndrome (PMWS) could be induced in healthy pigs following contact with air from pigs with clinical signs of PMWS. The pigs were housed in different units. Either 31 (study I) or 25 (study II) pigs with clinical symptoms of PMWS from a PMWS-affected herd and 25 healthy pigs from a PMWS-free, but PCV2-positive, herd were housed in unit A. Fifty pigs from a PMWS-free herd were housed in unit B, which were connected by pipes to unit A. In unit C, 30 pigs from a PMWS-free herd were housed as controls. In study II, the pigs in units A and B from the PMWS-free herd developed clinical signs of PMWS 2-3 weeks after arrival. PMWS was confirmed at necropsy and the diseased pigs had increased PCV2 load and increased antibody titers against PCV2 in serum that coincided with the development of clinical signs typical of PMWS. Sequence analysis revealed that the PCV2 isolate belonged to genotype 2b. In conclusion, the present study showed that PMWS can be induced in pigs from a PMWS-free herd by airborne contact with pigs from a PMWS-affected herd

Identification of the Receptor-Binding Protein in 936-Species Lactococcal Bacteriophages

The aim of this work was to identify genes responsible for host recognition in the lactococcal phages sk1 and bIL170 belonging to species 936. These phages have a high level of DNA identity but different host ranges. Bioinformatic analysis indicated that homologous genes, orf18 in sk1 and orf20 in bIL170, could be the receptor-binding protein (RBP) genes, since the resulting proteins were unrelated in the C-terminal part and showed homology to different groups of proteins hypothetically involved in host recognition. Consequently, chimeric bIL170 phages carrying orf18 from sk1 were generated. The recombinant phages were able to form plaques on the sk1 host Lactococcus lactis MG1614, and recombination was verified by PCR analysis directly with the plaques. A polyclonal antiserum raised against the C-terminal part of phage sk1 ORF18 was used in immunogold electron microscopy to demonstrate that ORF18 is located at the tip of the tail. Sequence analysis of corresponding proteins from other lactococcal phages belonging to species 936 showed that the N-terminal parts of the RBPs were very similar, while the C-terminal parts varied, suggesting that the C-terminal part plays a role in receptor binding. The phages investigated could be grouped into sk1-like phages (p2, fd13, jj50, and φ7) and bIL170-like phages (P008, P113G, P272, and bIL66) on the basis of the homology of their RBPs to the C-terminal part of ORF18 in sk1 and ORF20 in bIL170, respectively. Interestingly, sk1-like phages bind to and infect a defined group of L. lactis subsp. cremoris strains, while bIL170-like phages bind to and infect a defined group of L. lactis subsp. lactis strains

Identification of Lactococcus lactis Genes Required for Bacteriophage Adsorption

The aim of this work was to identify genes in Lactococcus lactis subsp. lactis IL1403 and Lactococcus lactis subsp. cremoris Wg2 important for adsorption of the 936-species phages bIL170 and φ645, respectively. Random insertional mutagenesis of the two L. lactis strains was carried out with the vector pGh9:ISS1, and integrants that were resistant to phage infection and showed reduced phage adsorption were selected. In L. lactis IL1403 integration was obtained in the ycaG and rgpE genes, whereas in L. lactis Wg2 integration was obtained in two genes homologous to ycbC and ycbB of L. lactis IL1403. rgpE and ycbB encode putative glycosyltransferases, whereas ycaG and ycbC encode putative membrane-spanning proteins with unknown functions. Interestingly, ycaG, rgpE, ycbC, and ycbB are all part of the same operon in L. lactis IL1403. This operon is probably involved in biosynthesis and transport of cell wall polysaccharides (WPS). Binding and infection studies showed that φ645 binds to and infects L. lactis Wg2, L. lactis IL1403, and L. lactis IL1403 strains with pGh9:ISS1 integration in ycaG and rgpE, whereas bIL170 binds to and infects only L. lactis IL1403 and cannot infect Wg2. These results indicate that φ645 binds to a WPS structure present in both L. lactis IL1403 and L. lactis Wg2, whereas bIL170 binds to another WPS structure not present in L. lactis Wg2. Binding of bIL170 and φ645 to different WPS structures was supported by alignment of the receptor-binding proteins of bIL170 and φ645 that showed no homology in the C-terminal part

Genotipizacija svinjskoga cirkovirusa tipa 2 izdvojenoga s različitih farmi u Hrvatskoj

Histopathological findings in 25 pig tissue samples, which indicated PCVD (porcine circovirus diseases), were studied. Pig tissue samples originated from 5 different pig-farms in the north-west part of Croatia. Histopathological lesions showed two clinical pictures of the disease: porcine multisystemic wasting syndrome (PMWS) and porcine dermatitis nephropathy syndrome (PDNS). All samples were tested by PCR for the presence of porcine circovirus type 2 (PCV2). Twenty of them were PCV2 positive. PCV2 DNA was quantified by realtime-PCR in all twenty samples with a wide range of PCV2 loads ranging from 105 to 1010 PCV2 genomes/μL. The highest PCV2 loads were detected in pigs with PMWS lesions, while PDNS affected pigs had lower PCV2 loads. The 20 PCV2 isolates were sequenced and analyzed. Nineteen isolates belonged to PCV2 group 1 and only one to PCV2 group 2. We found no link between genotypes and clinical form of the disease.U ovom su radu izneseni patohistološki rezultati 25 uginulih svinja s pet različitih svinjogojskih farmi na području sjeverozapadne Hrvatske, koje su uginule pod znakovima sindroma kržljavosti odbijene prasadi i sindroma nekrotičnoga dermatitisa. Klinički i patohistološki nalazi upućivali su na cirkovirusnu infekciju svinja. Lančanom reakcijom polimerazom dokazana je virusna DNK svinjskog cirkovirusa tipa 2 u dvadeset tkivnih uzoraka. Ti su uzorci nadalje bili pretraženi lančanom reakcijom polimerazom u stvarnom vremenu kako bi se ustanovila količina virusne DNK. U svim uzorcima ustanovljena je značajna količina virusnoga genoma, koja je iznosila između 105 i 1010 kopija genoma/μL. Veća količina virusa dokazana je u onim uzorcima koji su potjecali od svinja uginulih pod znakovima sindroma kržljavosti, a nešto manja količina virusa dokazana je u svinja koje su bolovale od sindroma nekrotičnoga dermatitisa. Svi PCR-proizvodi sekvencirani su kako bi se ustanovila pripadnost određenom genotipu svinjskoga cirkovirusa tipa 2 (SCV-2). Devetnaest izolata od dvadeset sekvenciranih, genotipski pripada skupini 1 SCV-2, a samo jedan izolat skupini 2 SCV-2. Takva genotipska pripadnost podudarna je s podatcima iz drugih europskih zemalja, gdje prevladava genotip 1 SCV-2 od 2003. god., a prije toga je dominirao genotip 2 SCV-2 kao etiološki čimbenik cirkovirusnih bolesti svinja