Location: Ruminant Diseases and Immunology Research
2022 Annual Report
Objectives
Objective 1: Compare Holstein cattle with a 1964 mastitis-resistant genetic background with modern mastitis-susceptible genetic background, identify genetic and immunologic traits that account for improved resolution of clinical mastitis against common mastitis pathogens and disease resistance through the periparturient period.
Sub-objective 1.A: Compare the immune response to infection with Staphylococcus aureus between the two populations of Holsteins in both the acute and chronic phases of the disease.
Sub-objective 1.B: Determine the impact of 1964 genetics on the proteome of innate immune cells during the periparturient period in comparison to cows with modern genetics.
Objective 2: Facilitate the development of antibiotic alternatives to prevent and treat mastitis by identifying, isolating, and testing important components of bovine mammary gland dry secretions.
Sub-objective 2.A: Fractionate components of mature bovine mammary gland dry secretions to identify portions that may be further developed as non-antibiotic mastitis preventive or treatment.
Sub-objective 2.B: Determine if there are unique antimicrobial components to the 1964 cows’ dry secretion.
Approach
Mastitis is the most prevalent infectious disease in dairy herds and the costliest disease for dairy producers. Newer estimates of mastitis' economic impact on the dairy industry calculate a single clinical mastitis case costs an estimated $586. Antibiotics and proper cow management are the mainstays for mastitis treatment and control. Dairy cattle with mastitis plus antibiotic dry treatments account for more antibiotic usage than all other dairy cattle diseases combined. To reduce antibiotic use, we need to understand better how the immune system fails to eliminate mastitis infections. A unique resource, available through a collaboration with researchers at the University of Minnesota, is a herd of Holsteins that have not been subjected to selective breeding since 1964. These 1964 cows were compared to cows with modern genetics for their ability to respond to an experimental mastitis challenge with Escherichia coli. The 1964 cows were able to clear the infection almost immediately and had fewer clinical signs of infection. A long-term goal is to identify genetic traits that allow the 1964 cows' immune system to protect the host better. Identification of these immunological traits may allow us to bring back these immunological advantages into modern dairy cows. We will use experimental mastitis models, bacterial inhibition tests, and proteomic assays to determine differences between modern and 1964 cows' ability to recognize and destroy pathogens. We will challenge cows with Staphylococcus aureus, isolate antibacterial components in dry secretion, and demonstrate protein changes between modern and 1964 cows during the periparturient period. Isolation and identification of traits that grant greater resistance to mastitis will be used to genetically breed for more resistant animals or products using isolated compounds as therapeutics.
Progress Report
Collaboration with researchers at the University of Minnesota has made available a herd of Holsteins that have not been subjected to selective breeding since 1964. These 1964 cows were compared to cows with modern genetics for their ability to respond to an experimental mastitis challenge with Escherichia coli. The 1964 cows cleared the infection almost immediately and had fewer clinical signs of infection. A long-term goal is to identify genetic traits that allow the 1964 cows' immune system to protect the host better.
Due to a shift in the direction of objectives for this project, the first-year objectives are fundamental. All objectives were accomplished. The mastitis experiment described in Objective 1A, comparing clinical responses of a Staphylococcus aureus intramammary infection in cows with a genetic background from 1964 and modern genetics cows, was accomplished. Samples have been stored or sent out for analysis.
We have been able to work with Animal Resources staff at NCAH to breed enough cows for the experiments described in Objective 1B. This objective will examine the proteomic differences in immune cells in 1964 and modern cows through the periparturient period.
Dry cow secretions were obtained from the 1964 cows and modern cows at the end of a lactation cycle. These samples have been properly stored and are awaiting analysis.
Accomplishments
1. Established that 1964 cows respond better to a mastitis challenge than modern cows. Previous work established that 1964 cows have a more robust innate immune response compared to modern cows. We hypothesized that 1964 cows would exhibit greater resistance to an intra-mammary infection than modern cows. ARS researchers in Ames, Iowa, showed that cows with genetics found in 1964 could clear experimental mastitis bacteria almost immediately and had fewer clinical signs of infection than modern Holsteins. Bacteria was barely detectable in the 1964 cows in contrast to the modern cows, which had nearly 100,000 bacteria per milliliter of milk after 12 hours of infection. Surprisingly, the milk immune cell counts were similar in both genotypes despite the massively lower bacterial counts in the 1964 cows. This suggests that 1964 cows have an innate immune system that is far more effective than that of modern Holsteins. Nearly 1,000 genes were differentially expressed in the immune cells in blood found in modern cows when comparing samples obtained before infection with those collected 48 hours after infection. In contrast, only 71 genes were differentially expressed in the 1964 cows for the same time points. This research has shown an essential difference between modern and 1964 cows in their ability to respond to mastitis challenge. This work is a prelude to finding the genes and mechanisms that allowed better immune competency in 1964 cows and bringing those genes back into the modern dairy cow. Once the genes and mechanisms that improve immune competency are identified, it will be possible to select them in the modern Holstein, minimizing mastitis and improving milk production.
Review Publications
Lippolis, J.D., Putz, E.J., Reinhardt, T.A., Casas, E., Weber, W.J., Crooker, B.A. 2022. Effect of Holstein genotype on immune response to an intramammary Escherichia coli challenge. Journal of Dairy Science. 105(6):5435-5448. https://doi.org/10.3168/jds.2021-21166.
Almeida, A.M., Ali, A., Ceciliani, F., Eckersall, P., Hernandez-Castellano, L.E., Han, R., Hodnik, J.J., Jaswal, S., Lippolis, J.D., McLaughlin, M., Miller, I., Mohanty, A.K., Mrljak, V., Nally, J.E., Nanni, P., Plowman, J.E., Poleti, M.D., Ribeiro, D.M., Rodrigues, P., Roschitzki, B.,Schlapbach,R., Staric, J., Yang, Y., Zachut, M. 2021. Domestic animal proteomics in the 21st century: a global retrospective and viewpoint analysis. Journal of Proteomics. 241. Article 104220. https://doi.org/10.1016/j.jprot.2021.104220.
Putz, E.J., Fernandes, L., Sivasankaran, S., Bayles, D.O., Alt, D.P., Lippolis, J.D., Nally, J.E. 2022. Some like it hot, some like it cold; Proteome comparison of Leptospira borgpetersenii serovar Hardjo strains propagated at different temperatures. Journal of Proteomics. 262(2022). Article 104602. https://doi.org/10.1016/j.jprot.2022.104602.
Putz, E.J., Sivasankaran, S.K., Fernandes, L.G., Brunelle, B.W., Lippolis, J.D., Alt, D.P., Bayles, D.O., Hornsby, R.L., Nally, J.E. 2021. Distinct transcriptional profiles of Leptospira borgpetersenii serovar Hardjo strains JB197 and HB203 cultured at different temperatures. PLOS Neglected Tropical Diseases. 15(4). Article e0009320. https://doi.org/10.1371/journal.pntd.0009320.
Fernandes, L.G., Putz, E.J., Stasko, J.A., Lippolis, J.D., Nascimento, A.L., Nally, J.E. 2022. Evaluation of LipL32 and LigA/LigB knockdown mutants in Leptospira interrogans Serovar Copenhageni: impacts to proteome and virulence. Frontiers in Microbiology. 12. Article 799012. https://doi.org/10.3389/fmicb.2021.799012.
