Evaluation of the Humoral Immune Response and Milk Antibody Transfer in Cattle vaccinated with inactivated H5 Avian Influenza vaccine
This study evaluated the efficacy of various doses of an inactivated H5 AI vaccine in cattle and assessed antibody transfer in milk against a recent bovine isolate of HPAI A(H5N1, clade 2.3.4.4b). Calves were inoculated with different vaccine doses, while lactating cows received the vaccine four weeks later. The humoral immune response was measured using the Hemagglutination Inhibition (HI) test and ELISA. Results showed a dose-dependent immune response, with higher doses producing stronger and more sustained antibody levels. Group 1 maintained a stable HI titer of 6 log2, while Groups 2, 3, and 4 peaked at 8, 9, and 9 log2, respectively, by the fourth week post-vaccination. Milk antibody transfer was observed, with strong positive responses in milk samples by the second week post-vaccination. The ID Screen ELISA demonstrated higher sensitivity for detecting antibodies in milk compared to serum. The immune response to the AI vaccine differed from responses to other vaccines used in cattle such as Foot and Mouth Disease Virus (FMDV) and Lumpy Skin Disease Virus (LSDV), indicating the need for optimizing vaccine dosage and formulation, including adjuvant and antigen content. Future research should extend the monitoring period, increase sample sizes, and explore different vaccine formulations to develop effective vaccination strategies for cattle.
The study revealed a clear dose-dependent pattern in the cattle's immune response to the H5 avian influenza vaccine, with higher doses resulting in stronger and more sustained antibody responses. Even the lower doses provided significant antibody protection, achieving titers within the protective range of 5 to 7 10g2, as established in chickens. A minimum hemagglutination inhibition (HI) titer of ≥ 5 log, has been suggested as a serological potency standard indicative of protection, safeguarding birds against mortality. Furthermore, HI titers of ≥ 7 log, have been associated with the prevention of virus shedding from the oropharynx in vaccinated birds [19, 26]. This response was corroborated by the ID Screen ELISA results. Notably, the humoral immune response in all vaccinated groups elicited a rapid and high antibody response within the early weeks post-vaccination. This response stabilized quickly and persisted consistently throughout the experimental period.
However, the cattle's immune response to the H5 Al vaccine differed markedly from their responses to other vaccines, such as those for Foot and Mouth Disease Virus (FMDV) [27, 28, 29] and Lumpy Skin Disease Virus (LSDV) [30]. Several factors could explain these differences. The adjuvant and antigen composition of the H5 Al vaccine may be particularly effective in inducing a strong and stable immune response in cattle, unlike the formulations used for FMDV and LSDV vaccines. Additionally, the H5 Al vaccine may possess higher immunogenicity in cattle compared to the FMDV and LSDV vaccines, leading to a more robust production of antibodies. The nature of the H5 avian influenza virus itself may trigger a different immune mechanism in cattle[31], resulting in a distinct and more effective antibody response compared to other viruses. Furthermore, the observation of a dose-dependent response underscores the importance of optimizing vaccine dosage, as higher doses of the H5 Al vaccine achieved better immune responses, a factor that might need consideration for other vaccines. Finally, the rapid stabilization and persistence of the antibody response to the H5 Al vaccine suggest that the immune system of cattle responds more favorably to this particular vaccine's stimulation.
Conclusion
The study demonstrated that the H5 avian influenza vaccine induces a robust, dose-dependent immune response in cattle, with higher doses yielding stronger and more sustained antibody production. The findings underscore the importance of optimizing vaccine dosage and formulation to enhance immune efficacy. The rapid stabilization and persistence of the immune response highlight the vaccine's potential effectiveness in cattle, a response distinct from that elicited by other vaccines used in cattle.
Additionally, the study observed effective milk antibody transfer in lactating cows, indicating that the vaccine not only elicits a systemic immune response but also facilitates the transfer of antibodies through milk. Future research should focus on refining vaccine formulations, considering adjuvant and antigen content, extending the monitoring period, and further investigating milk antibody transfer to optimize the immune response in bovine populations. These efforts are crucial for developing effective vaccination strategies to safeguard cattle against avian influenza and potentially other infectious diseases.
Please sign in or register for FREE
If you are a registered user on Research Communities by Springer Nature, please sign in