ANTIGEN-INDUCED PROTECTION AGAINST INFECTION WITH TOXOCARA-VITULORUM LARVAE IN MICE

Larvae of Toxocara vitulorum hatched and migrated in the tissues of normal mice. Larvae survived in reasonable numbers, particularly in the liver and, to a lesser extent, in the lungs and kidneys, for at least 4-7 days and in muscles, albeit only in low numbers, for at least 3 weeks. Oral infection of mice on three or more occasions with T. vitulorum eggs induced protection against a challenge infection with eggs of T. vitulorum. Prior parenteral immunization of mice with a variety of T. vitulorum soluble antigens (extracts, excretions/secretions, or perienteric fluid and their fractions) from adult parasites and/or infective larvae induced statistically significant protection against infection. The most effective protective immunogens were three or more injections with perienteric fluid from adults (100% protection) and excretions/secretions from infective larvae of T. vitulorum (>92% protection).