The lipopolysaccharide (LPS) was extracted by using digestive enzyme and hot phenol water method from Pseudomonas aeruginosa P (10) a local isolate from patient suffering from eye infection-and partially purified by gel-filtration chromatography. The sera were prepared in rabbits, they were injected with five doses over 70 days of different concentrations of partially purified LPS. The pathological infection was done by using two groups of female mice; the first group represents the

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... d group while the second group represents the immunized group. The left and right eyes of the two groups were scratched then the left eyes were infected with P. aeruginosa P (10) while the right eyes serve as a control scratched eye. In the second group that represents the immunized group, the mice were immunized intraperitoneally (i.p.) with sera after and before scratching and infection with P. aeruginosa. The results have shown that the typical pathological scores were observed in the left eyes of non-immunized mice group 72hr. after infection with P. aeruginosa while no pathological scores were observed in the left eyes of immunized mice. This indicated that the immunization with LPS gave a protection against P.aeruginosa corneal infection. These results indicate that immunization with LPS reduces the corneal infection caused by P. aeruginosa.