BALB/c mice elicit an IgG immune response against Y. enterocolitica LPS, but is not protective against B. abortus infection. A) ELISA response of the sera obtained from the third bleed (1/200 dilution) of the different mouse groups against Y. enterocolitica O:9 LPS. Microtiter plates were coated with 12.5 μg of Y. enterocolitica O:9 LPS. Each datum point represents the average of three replicate wells. Response was read after 1 h @ 37°C at OD405 nm. The bar in each set of data corresponds to the average of each group.