1

Speaker(s)：

Yu-Liang Huang

Topic

The molecular epidemiology of porcine reproductive and respiratory syndrome virus

Abstract

Since porcine reproductive and respiratory syndrome virus (PRRSV) was first identified in Taiwan at 1992, it is general in the Taiwan pig farms and induces the huge loss for pig producers. The aim of this study was to assay the molecular epidemiology of PRRSV in Taiwan. The PRRSV strains between 1992 and 2012 were collected and sequenced. The sequences were aligned the CLUSTAW program and phylogenetic analysis used the Neigbor-Joining method by MEGA 5.2 software. The results showed that the Taiwan PRRSV strains were all North American genotype. The percent identity of nucleotide (NT) of complete genome between Taiwan strains and MLV vaccine strain was 85.2 to 99%. Compared with the Hipra vaccine strain, there was 59.2-60%. Further, the percent identity of ORF5 NT and amino acids (AA) was assayed. The percent identity of ORF5 NT and AA between Taiwan strains and MLV vaccine strain was 84.4-99.5% and 82.6-98.5%, respectively. The percent identity of ORF5 NT and AA between Taiwan strains and Hipra vaccine strain was 62.1-64.5% and 55.3-59.9%, respectively. The percent identity of ORF5 AA between Taiwan/2012 strains and MLV or Hipra vaccine strain was 82.6-86.1% and 56.3-59.9%, respectively.

2

Speaker(s)：

Chyi-Sing, Hwang

Topic

Detection of simian type D retrovirus

Abstract

To set up healthy macaques for experimental uses, retroviral diseases in macaque were detected. In published studies, samples were first screened for the presence of simian type D retrovirus (SRV) antibodies by enzyme-linked immunosorbent assay (ELISA) or immunofluorescence assay (IFA). Positive or borderline samples were then tested by Western blot assay. The previous result tested by commercial ELISA kits showed SRV-seronegative.

Because inapparent carriers of SRV may be antibody-negative, but will have virus in blood. To investigate the presence of SRV antigen in macaques, the proviral DNA of SRV was detected by PCR. All blood samples were negative. According to the results of real-time PCR, these macaques did not carry SRV. The SRV-free macaques can be used for experimental purposes.

3

Speaker(s)：

Cheng-chu Hsieh

Topic

Development of Salmonella vaccine for poultr

Abstract

Pullorum Disease (PD) is a prevalent poultry disease around the world. Poults under 3 month of age are the most sensitive population to PD, and the mortality is 30-40% in average, and may be up to 100%. PD is caused by Salmonella pullorum, which is gram-negative, non-motile rod. The mortality is increased upon transportation, cold weather, and poor management. The main reservoirs of pullorum infection are the egg-producing organs of the infected hen. Some pullorum carrying eggs could not be hatched, thus causes the reduction of hatch rate. The disease is transmitted also through consumption of litter, feed, or water contaminated with infected droppings. Infected chicks or poults that do not die of the disease may grow to maturity and remain lifetime carriers. Right now, there is no available PD vaccine; an aggregation assay based PD diagnosis reagent is commonly used to screen this disease in Taiwan. The aim of this study is to develop formaldehyde inactivated vaccine for PD. We used biochemical methods and polymerase chain reaction (PCR) to identify the pullorum strain, and conclude that the LD₅₀ of Salmonella pullorum in ICR mice is 2.9×10⁵ CFU. We report here that the mice vaccinized with 10⁹ or 10¹⁰ inactivated Salmonella pullorum exhibited 100% of survival rate after challenge of 100-fold LD₅₀ of wild type pullorum. These results demonstrate that the inactivated vaccine of PD can provide protection upon Salmonella pullorum infection in mice.