Field trials evaluating the efficacy of porcine epidemic diarrhea vaccine, RNA (Harrisvaccine) in the Philippines.

Porcine epidemic diarrhea (PED) is a devastating enteric disease causing economic losses in many countries including the Philippines. To control PED, apart from oral administration of minced intestinal materials, there are still no effective control methods. The ability of porcine epidemic diarrhea vaccine RNA particle platform (PED-RP) to induce antibody in colostrum and milk samples was investigated in two pig herds with a differing PED status in the Philippines. Herd-A was naïve but herd-B was endemically infected with PED. Sera, colostrum, and milk samples were collected prior to and following vaccination, and assayed for the presence of antibody by viral neutralization (VN) and IgG and IgA levels by ELISA spike protein. The results from both herds, compared to the non-vaccinated control group, demonstrated significantly increased VN titers and IgG and IgA levels in colostrum and milk samples of sows at 0, 7, 14, and 21 days post parturition. Additionally, piglets from vaccinated sows had VN titers, and IgG and IgA levels are significantly higher than those from non-vaccinated sows. In conclusion, the results of the study demonstrate that PED-RP can be used to induce a satisfactory antibody response in colostrum and milk, as measured by VN titers and IgG and IgA levels.

Melamine- and cyanuric acid-associated renal failure in pigs in Thailand.

A newly observed syndrome characterized by progressive weight loss, pallor, and high mortality was reported in many swine herds across Thailand from February through May 2007. To determine the cause of the new syndrome, 5 pigs, 4-8 weeks of age, were submitted to the diagnostic laboratory for necropsy examination. All 5 pigs were underweight, with pallor and rough coats. The kidneys of all 5 pigs were yellowish and slightly swollen, with precipitation of crystalline material on the cut surface. Histologically, epithelial degeneration and necrosis were evident in proximal and distal tubules and collecting ducts. Round, yellow-brown crystals with radiating striations were diffusely distributed through the lumen of proximal and distal tubules and collecting ducts. Blood urea nitrogen and creatinine levels were elevated. Melamine and analogs, including cyanuric acid, were detected by gas chromatography mass spectrometry. The evidence reported here suggests that melamine- and cyanuric acid-adulterated feed caused renal failure in these pigs.

The first detection of Senecavirus A in pigs in Thailand, 2016.

We report the first detection of Senecavirus A (SVA) in nine of 12 (75%) pigs in Thailand in 2016. The full-length genome demonstrated that Thai SVA isolates were closely related to the first Canada strain (11-55910-3) than the recent strains causing outbreaks in Brazil, the United States and China in 2015-2016.

Porcine circovirus type 2 (PCV2) distribution and replication in tissues and immune cells in early infected pigs.

Replication of porcine circovirus type 2 (PCV2) in pigs, as measured by spliced capsid mRNA (Cap mRNA) and viral DNA, was investigated following experimental infection. Peripheral blood mononuclear cells (PBMCs), and tissue from bronchial lymph nodes (BLN), inguinal lymph nodes (ILN), tonsils, lungs, liver, kidneys, spleen and thymus from infected pigs on different days post-infection (DPI) were assessed. PCV2 replication differed dramatically between tissues from the same infected pig. The virus actively replicated in most tested tissues at 14DPI in association with increased PCV2 associated lesions and PCV2 antigen levels, although no clinical signs correlated with PCV2 associated disease were observed in infected pigs during the course of the study. The PCV2 Cap mRNA was detected only at 13DPI in PBMCs from infected pigs, suggesting replication of the virus in circulating blood is transient and not a major site for PCV2 replication in vivo. Evaluation of the Cap mRNA and viral DNA synthesis in T and B lymphocyte and monocyte populations from PBMCs and BLN at various intervals post-inoculation revealed replication of PCV2 in all cell subpopulations; however, viral replication in B lymphocytes was greater than observed in mononuclear cells isolated from BLN at 14DPI indicating that B lymphocytes may be an important cell population for PCV2 replication. These findings further our understanding of the cell types permissive for PCV2 replication and the pathogenesis of PCV2 infection in vivo.

Different Lineage of Porcine Deltacoronavirus in Thailand, Vietnam and Lao PDR in 2015.

Porcine deltacoronavirus (PDCoV) was detected by RT-PCR in 12 of 97 (12.4%) intestinal samples collected during 2015 from piglets with diarrhoea in Thailand, Vietnam and Lao PDR. Spike, membrane and nucleocapsid genes were characterized, and phylogenetic analyses demonstrated that PDCoV isolates from Thai and Lao PDR form a novel cluster, separated from US and China isolates, but relatively were more closely related to China PDCoV than US isolates. Vietnam PDCoVs, however, were grouped together with US PDCoV. The analyses of amino acid changes suggested that they were from different lineage.

The effect of a killed porcine reproductive and respiratory syndrome virus (PRRSV) vaccine treatment on virus shedding in previously PRRSV infected pigs.

Two experiments were conducted to investigate if virus shedding could be reduced following a killed porcine reproductive and respiratory syndrome virus (PRRSV) vaccination (KV) of PRRSV infected pigs. In experiment 1, PRRSV infected pigs were vaccinated with KV on days 14 and 28 following infection. Viremia and serum neutralizing (SN) antibody were compared to infected pigs with no KV. The second experiment was conducted in an identical manner. In addition to viremia and SN antibody, virus in oropharyngeal scrapings and interferon gamma (IFN-gamma) producing cells were monitored. Magnitude and duration of viremia were not different between KV vaccinated and non-vaccinated groups. No virus was detected in oropharyngeal scraping from any pig, nor was there a difference in the detection of viral RNA. In both experiments, however, increases in SN titer and number of IFN-gamma producing cells were observed. The SN titer was significantly higher in KV vaccinated groups than in non-vaccinated group on days 42 and 42-56 following infection in experiments 1 and 2, respectively. The number of IFN-gamma producing cells was slightly higher in KV vaccinated groups than in non-vaccinated group on days 42 and 63. These observations suggest that KV had no effect on virus shedding. However, previously infected pigs responded immunologically to KV, as demonstrated by increases in SN antibody titers and IFN-gamma producing cells.