Investigations of protective effects of bivalent inactivated vaccine prepared from serotypes 1/2a and 4b Listeria monocytogenes on mice

Abstract

The objective of these investigations was to check on laboratory white mice the protective effect of an inactivated bivalent vaccine prepared from serotypes 1/2a and 4b L. monocytogenes. Following verification of the sterility and toxicity of the prepared vaccine, the mice were divided into 6 groups with 10 animals in each group. The first and second group of mice were administered the vaccine without saponin (vaccine A) and the third and fourth group the vaccine with saponin (vaccine B). Mice of the fifth and the sixth group were not vaccinated and served as a negative control. Two weeks following vaccination, the experimental groups were revaccinated, with the exception of the two control groups. Two weeks following revaccination, all groups were artificially infected with serotypes 1/2a and 4b L. monocytogenes. During the course of the investigations (60 days) a total of 4 mice died in the vaccinated groups. Mice of the control groups started dying after day 7, and the last mouse in these groups died 14 days after the infection. Examinations of preparations of parenchymatous organs of the dead mice stained according to Gram proved the presence of L. monocytogenes. Homogenates of parenchymatous organs were sown on tryptose agar for reisolation and a pure culture of L. monocytogenes was obtained. Through the use of specific antiserums, serotypes 1/2a and 4b were confirmed. Considering the total number of vaccinated mice in the experiment and the percent deaths (10%), it can be said that the investigated vaccine with saponin had a satisfactory protective effect.

Cilj ovog istraživanja bio je da se na laboratorijskim belim miševima proveri zaštitno dejstvo inaktivisane dvovalentne vakcine pripremljene od serotipova L. monocytogenes 1/2a i 4b. Nakon provere sterilnosti i toksičnosti pripremljene vakcine miševi su podeljeni u 6 grupa sa po 10 životinja. Prva i druga grupa miševa su dobile vakcinu bez saponina (vakcina A), a treća i četvrta grupa vakcinu sa saponinom (vakcina B). Miševi pete i šeste grupe nisu vakcinisani i služili su kao negativna kontrola. Dve nedelje nakon vakcinacije izvršena je revakcinacija oglednih grupa, osim kontrolnih. Dve nedelje nakon revakcinacije izvršena je veštačka infekcija svih grupa sa serotipovima L. monocytogenes 1/2a i 4b. Za vreme ispitivanja (60 dana) uginula su 4 miša iz vakcinisanih grupa. Miševi kontrolnih grupa su počeli da uginjavaju nakon 7. dana, a poslednji miš je uginuo 14 dana posle infekcije. Pregledom preparata iz parenhimatoznih organa uginulih miševa obojenih po Gramu dokazano je prisustvo L. monocytogenes. Zasejavanjem homogenizata parenhimatoznih organa na triptozni agar urađena je reizolacija i dobijena je čista kultura L. monocytogenes. Upotrebom specifičnih antiseruma potvrđeni su serotipovi 1/2a i 4b. S obzirom na ukupan broj vakcinisanih miševa u ogledu i procenat uginuća (10%), može se reći da je ispitivana vakcina sa saponinom imala zadovoljavajuć i zaštitni efekat.