Vaccination against Rabbit Hemorrhagic Disease Virus 2 (RHDV2) Using a Baculovirus Recombinant Vaccine Provides Durable Immunity in Rabbits.

Rabbit hemorrhagic disease virus 2 (RHDV2) emerged in the United States in 2018 and has spread in both domestic and wild rabbits nationwide. The virus has a high mortality rate and can spread rapidly once introduced in a rabbit population. Vaccination against RHDV2 provides the best protection against disease and should be considered by all rabbit owners. Here, we investigate the duration of immunity provided by vaccination with the Medgene Platform conditionally licensed commercial vaccine 6 months following the initial series. Rabbits received either the vaccination or a placebo and were challenged with RHDV2 6 months later. All vaccinated rabbits survived challenge whereas 18/19 non-vaccinated controls succumbed to infection within 10 or fewer days post-challenge. These results demonstrate lasting immunity following vaccination with the Medgene RHDV2 vaccine.

Canine peripheral blood lymphocyte phenotyping by 7-color multiparameter flow cytometry.

OBJECTIVE: To characterize baseline canine lymphocyte phenotypes including lymphocytes coexpressing multiple markers by novel 7-color multiparameter flow cytometry. STUDY DESIGN: Fresh canine peripheral blood lymphocytes of 79 healthy 26-week-old Beagle or Beagle-mix dogs were stained and analyzed. RESULTS: The high number of samples and acquired flow data (averaging 1.9 x 10(5) cells/sample) allowed the detection of minor lymphocyte subsets coexpressing multiple lymphocyte markers. The averaged percentages of major lymphocyte subsets of CD3+, CD4+, CD8+, CD21+ and gammadelta TCR+ cells from this study were 74.0, 43.6, 14.3, 9.6, and 0.2, respectively, which were comparable but uniquely different from other reports as they were simultaneously detected in the same sample. We demonstrated that the commonly used CD21 and CD3 monoclonal antibody (mAb) clones, previously recommended not to be used in the same staining, could and should be used together with the proper steps of lymphocyte gating. We found a high percentage (10.3%) of unidentified CD21- CD3+ CD4- CD8-gammadelta TCR- lymphocyte subset that has never been reported. The intensive gating strategy and the mean percentages of each lymphocyte subset to their parent subsets and to the total lymphocyte population are presented and discussed. CONCLUSION: The canine lymphocyte phenotypes were fully characterized. This novel multiparameter flow cytometry method is a powerful approach to in-crease the accuracy of lymphocyte phenotyping in dogs.