536 Immunopathogenesis of Avian Influenza in the mammalian mammary gland

Objectives/Goals: Our aim is to determine the pathogenesis of intramammary infection of H5N1. First, we must induce lactation, and our aim was to create a protocol to induce lactation without impregnating mice. We hypothesize that the immunological milieu of a lactating mammary gland is highly conducive for influenza viral infection. Methods/Study Population: Nine 10-week-old female mice of unidentified strain were placed in cohorts of lactating versus non-lactating versus control (undeveloped mammary glands) groups. Animals were co-housed within their group. Lactogenic hormones were used to induce mammary development and lactation, including estradiol, progesterone, oxytocin, and prolactin. Mice were inoculated with a comparative strain to H5N1, H1N1, due to its increased availability and safety standards. Immunopathology of mammary tissues and lungs will be assessed by histology, viral titration, and flow cytometry, and data analysis is pending. Results/Anticipated Results: All seven mice that were chosen to be injected with lactogenic hormones developed mammary tissue beyond the pubertal stage and into the reproductive stage, as expected if they were pregnant. Of those seven mice, the three that were given prolactin and oxytocin for milk production and let down were able to lactate. Plaque assays of mammary and lung tissue revealed no viral titers. Flow cytometry of innate surface markers showed varying results and were deemed inconclusive. Based on the preliminary data, it is inconclusive whether the mammary tissue was able to support H1N1 virus replication. Discussion/Significance of Impact: Better understanding of the immunopathology of the mammary gland and how it contributes to disease and disease transmission of influenza in mammalian species will be essential for the development of measures to control disease outbreak and minimize economic loss, especially in species such as cattle and goats.