Inhibition of oral pathogens and collagenase activity by seaweed extracts.

Fifty-seven species of common seaweed from the Coast of Korea were screened for antimicrobial (i.e. inhibition of Prevotella intermedia and Porphyromonas gingivalis growth) activity. As a source of bioactive compounds, seaweeds can produce many secondary metabolites with a variety of activities. Using the agar diffusion method, only 17 species (29.8%) showed inhibitory activity. Of these, methanol extracts of Enteromorpha linza, Sargassum sagamianum, and Ulva pertusa showed strong inhibitory effects against both P. intermedia and P. gingivalis. The MIC values of E. linza, S. sagamianum, and U. pertusa extracts against P. intermedia were 625, 78 and 625 Ag ml-1 and those against P. gingivalis were 312, 156 and 625 Ag ml-1, respectively. When these three species’ extracts were separated into five fractions according to their polarity, the main active agents were determined to be phenolic compounds. We then compared the antimicrobial activities of these phenolic compounds against various periodontal pathogens using a MIC test. Phenolic compound containing extracts at concentrations of 10 to 100 Ag ml-1 showed a moderate to significant inhibitory effect on collagenase 1, 2 and 3 activity.

Neutralization of white spot syndrome virus (WSSV) for Penaeus chinensis by antiserum raised against recombinant VP19.

This study was carried out to neutralize the WSSV one of the most virulent pathogen causing large economic damage in shrimp culture industry using the antiserum produced against recombinant WSSV envelope protein VP19 (rVP19) as a tool to evaluate WSSV infection mechanism. A fragment of VP19 was expressed in Sf21 insect cell using baculovirus expression system as fusion protein with 6 His-tag. Then, polyclonal antiserum against rVP19 was raised in white rabbit. A constant amount of WSSV (at 10(4) diluted stock) was incubated with various antiserum concentrations and injected into shrimp, Penaeus chinensis, for the neutralization challenge. At 9 days post injection, the shrimp in the positive control injected with WSSVshowed 100% mortality The shrimps injected with WSSV preincubated with preimmune serum showed 83.3% mortality at 15 days post injection. The shrimps injected with the WSSV preincubated with 1 microl, 5 microl or 10 microl r VP19 antiserum and shrimp mortalities showed 66.6%, 40.0% and 26.6% at 15 days post injection, respectively The high concentration of antiserum group showed lower mortality than those of the low concentration of antiserum group. This indicates that the WSSV can be neutralized by the rVP19 antiserum in a dose-dependent manner. The neutralization challenge result suggested that VP19 might play an important role in WSSV infection to shrimp.

Production of polyclonal antibody against recombinant ORF 112 L of rock bream (Oplegnathus fasciatus) iridovirus (RBIV) and in vitro neutralization.

Rock bream iridovirus (RBIV) is a causative agent of epizootics among cultured rock bream (Oplegnathus fasciatus) in Korea. In this study, the immunogenic property of ankyrin repeats gene (ORF 112L) from RBIV was evaluated to develop vaccines against RBIV. ORF 112L of RBIV was cloned into expression vector of pGEX-4T-1. The recombinant protein was successfully expressed using E. coli BL21 (DE3). The soluble recombinant RBIV protein was applied to affinity column for the purification of the protein. Mice were immunized by the injection of purified recombinant protein to produce polyclonal antibodies. EUSA was carried out to identify the immune reaction abilities of polyclonal antibody to recombinant protein. The antigenic property of this protein was evaluated by using in vitro neutralization with BF-2 cells. In neutralization test, BF-2 cells infected with the mixture of RBIV and antisera containing anti-GST-ORF 112L polyclonal antibody were healthy showing few cytopathic effect (CPE) similar with the negative control (without RBIV). These studies suggest that the protein from the ankyrin repeats gene, ORF 112L of RBIV may play an important role in the mechanism of infection. Also, it can be possible to develop protein or gene vaccines using ORF 112L against RBIV.