Multisite phosphorylation of adipocyte and hepatocyte phosphodiesterase 3B.

Phosphodiesterase 3B (PDE3B) is an important component of insulin and cAMP-dependent signalling pathways. In order to study phosphorylation of PDE3B, we have used an adenoviral system to express recombinant flag-tagged PDE3B in primary rat adipocytes and H4IIE hepatoma cells. Phosphorylation of PDE3B after treatment of cells with insulin, cAMP-increasing agents, or the phosphatase inhibitor, calyculin A was analyzed by two-dimensional tryptic phosphopeptide mapping and mass spectrometry. We found that PDE3B is multisite phosphorylated in adipocytes and H4IIE hepatoma cells in response to all these stimuli. Several sites were identified; serine (S)273, S296, S421, S424/5, S474 and S536 were phosphorylated in adipocyte as well as H4IIE hepatoma cells whereas S277 and S507 were phosphorylated in hepatoma cells only. Several of the sites were phosphorylated by insulin as well as cAMP-increasing hormones indicating integration of the two signalling pathways upstream of PDE3B, maybe at the level of protein kinase B.

Multiplex reverse transcription-PCR for rapid differential detection of porcine epidemic diarrhea virus, transmissible gastroenteritis virus, and porcine group A rotavirus.

A novel multiplex reverse transcription polymerase chain reaction (multiplex RT-PCR) that can detect porcine epidemic diarrhea virus (PEDV), transmissible gastroenteritis virus (TGEV), and porcine group A rotavirus (GAR) was developed. The 3 viruses (PEDV, TGEV, and porcine GAR) are major agents in viral enteric diseases of piglets. As the clinical signs of these diseases are similar, including watery diarrhea, differential detection is required for etiologic diagnosis. A mixture of 3 pairs of published primers was used for amplification of viral nucleic acids, yielding 3 different amplicons with sizes of 859 bp, 651 bp, and 309 bp for TGEV, PEDV, and porcine GAR, respectively. A total of 157 specimens (78 fecal and 79 intestinal samples) from piglets with acute gastroenteritis were collected in Korea between January 2004 and May 2005. They were tested for the presence of 3 viruses by multiplex RT-PCR. Coinfections with PEDV and porcine GAR were identified in 16 farms (43.2%). PEDV, porcine GAR, and TGEV infection were 26.3%, 13.2%, and 2.7% respectively. The relative sensitivity and specificity of multiplex RT-PCR were evaluated, with results suggesting that this assay is equal in quality to conventional single-agent RT-PCR assays (sensitivity:100%, 92.9%, 100% for TGEV, PEDV, GARs; specificity: 100% for all 3 viruses). This multiplex RT-PCR is a simple assay and may be a potentially useful for rapid, sensitive, and cost-effective etiological diagnostic tool for acute viral gastroenteritis in piglets.

Detection of porcine circovirus type 2 in feces of pigs with or without enteric disease by polymerase chain reaction.

To establish the sensitive polymerase chain reaction(PCR) method and detect porcine circovirus type 2 (PCV2) from intestines and feces of commercial swine herds with or without enteric disease, intestinal samples from 68 pigs and 29 fecal samples from commercial swine farms were collected. A primer set, forward primer 5'-GAAGAATGGAAGAAGCGG-3' and reverse primer 5'-CTCACAGCAGTAGACAGGT-3', could detect the virus at a concentration as low as 2 infectious virions per milliliter under controlled conditions using PK-15 cell-adapted PCV2. The genomic nucleotide sequences of open reading frame 1 (ORF1) PCR products from fecal samples were found to have complete homology with other PCV2s deposited in the GenBank database. Transmissible gastroenteritis virus (TGEV) and porcine epidemic diarrhea virus (PEDV) as the other enteric pathogens were also investigated by performing duplex reverse transcription-PCR (RT-PCR). Among 63 pigs with clinical enteric disease, 18 PCV2s (14 from intestines and 4 from feces), 7 TGEVs from intestines, and 18 PEDVs (14 from intestines and 4 from feces) were detected by PCR and the duplex RT-PCR. In 34 pigs (14 from intestines and 20 from feces) without clinical enteric disease, only PCV2 was detected in 19 pigs (3 from intestines and 16 from feces). Both PEDV and PCV2 were found in 6 pigs with clinical enteric disease. Among 15 PCV2 samples that were PCR-positive, 4 were culture-positive at passage level 3 in PK-15 cells. These results reveal that PCV2 is shed through the feces of pigs without clinical enteric disease, which suggests the potentiality of the fecal-oral transmission of PCV2 in feces.