Extract from the thesis of Nguyen Dinh Dang

1. Brief introduction

– Title: “Study on production of egg yolk antibodies against pili for the control of diarrhea caused by E. coli in postweaning piglets”

– Author: Nguyen Dinh Dang

– Scientific supervisors:

Ass. Prof. Dr. Nguyen Viet Khong
Ass. Prof. Dr. Truong Van Dung

– Field of study: Microbiology Code: 62 62 50 10

– Institution: National Institute of Veterinary Research

2. Dissertation contents

2.1 Aims and objects of the study

The study is aiming at the production egg yolk possessing specific antibodies against pili of the E. coli that causes diarrhea in post weaning piglets, generate a byproduct that could be implemented in the field.

The major objects of study include E.coli F4-pili, egg yolk antibodies and derivative product, diarrhea piglets in particular the post weaning pig

2.2 Research methods

The main methodologies are composed of (i) Methodology to isolate and determine the diarrhea causative E.coli, (ii) immunization of hen using purified E.coli pili, (iii) Elisa testing for antibody titer, (iv) experimental matrix to determine the dose for treatment and prevention in the field condition and (v) field trial.

2.3 Research’s results and conclusions

Contents and outcome

In this thesis we have shown: (1) Pigs in all livestock models and geographical areas are exposed to commonly pathogenic E. coli strains including the F4, F5, F6 and F18 E.coli. Among the 60.90% of hemorrhagic E.coli, the rate of E. coli containing at least one of the genes encoding for the enterotoxins and adhesion is 76.47% for E. coli F4+, 18.82% for E. coli F18+, 3.53% for E. coli F5+ and 1.18% for E. coli F6+.

(2) We have established protocol for egg yolk antibody production, allowing to obtain specific antibodies against E.coli F4-pili at titer of 1/12.800. (3) the spay-dried egg yolk powder KT04 has “the treatment dose for postweaning diarrhea caused by E.coli in piglets is 1 gram per kilogram of body weight, in which the reconstitution of 0.33 g KT04 in 1 ml PBS, having specific antibody titer against F4-pili of 1: 640 by Ab-ELISA”.

(4) In field conditions, the KT04 product can cure over 70% of diarrheal pigs with an average doses of 4.30 ± 0.94 (1 g/KgP); at advance treatment dose (0.5 g/KgP) it reduced 60.45% in rate of diarrheal piglets as comparing to the non-KT04 control group. The implication of KT04 powder for prophylaxis has reduced 69.44% in number of diarrheal cases and 90.87% in number of doses and duration (if treatment may need) in comparison to the treatment by antibiotics; The KT04 product is safe, has no affect on the growth and weight gaining.

Scientific contribution: The thesis has provided a scientific data demonstrating the feasibility of the principle controlling diarrhea caused by E. coli by heterogonous antibodies that specifically prevents the conolization of etigent at the first entry in susceptible pigs.

Practical relevance: KT04 powder has cured over 70% cases of weaned diarrhea piglets, indicating thet this product has highly practical applications, minimizing the use of antibiotics in husbandry.

New output:

(i) It provides an ELISA procedure to determine egg yolk antibody titers, which allows quantitative testing of the antibody in the bio-product (both imported and domestic);

(ii) This is the first time in Vietnam, we used of purified antigen for production of specific egg yolk antibody and in particular we determined the therapeutic dose for treatment of E.coli F4+ infection, the main etigent causing diarrhea in postweaning piglet, and demonstrated the successfulness in an initial implication in the field.

(iii) We have demonstrated an example to combine the modem technology and the classical methodology to generate a product in need. This combination for egg antibody bears potential for the control of other pathogenic microorganism.