Cationic Liposome–Oligonucleotide Complex as an Alternative Adjuvant for Polyclonal Antibody Production in New Zealand White Rabbits (Oryctolagus cuniculus)

Because of their ideal size and temperament, rabbits are commonly used in polyclonal antibody production. Immunostimulatory adjuvants—such as Freund complete and incomplete adjuvants as well as various proprietary products—trigger a robust immune response, which increases antibody concentrations. However, these adjuvants can cause excessive soft tissue reactions, prompting concerns regarding animal wellbeing. This study assessed the safety and efficacy of cationic liposome– oligonucleotide complexes (CLDC) as an alternative adjuvant to conventional adjuvants. On days 0 and 14, 15 female New Zealand white rabbits were vaccinated subcutaneously with 15 μg ovalbumin mixed with either CLDC, Freund adjuvant (day 0, complete; day 14, incomplete), or a proprietary adjuvant (n = 5 per group). Antibody titers were measured by direct ELISA on days 0, 14, and 28. Rabbits were palpated daily for lesion development, and all lesions were measured. Rabbits in all groups developed a significant antibody response to ovalbumin over 28 d. However, the differences between groups were not statistically significant. No rabbits in the CLDC group developed skin lesions, whereas 80% of rabbits that received Freund adjuvant and 100% of those that received the proprietary product developed skin lesions. This study demonstrates that CLDC may be a valuable and effective alternative adjuvant for polyclonal antibody production in rabbits—one that avoids the palpable injection-site lesions often seen with other adjuvants.