THE DYNAMICS OF ERYTHROCYTE INFECTION IN BOVINE ANAPLASMOSIS: A FLOW CYTOMETRY-BASED ANALYSIS

MORETTA R.; PETRIGH R.; RUYBAL P.; MESPLET M.; WILKOWSKY SE; MEIKLE V.; TORIONI DE ECHAIDE S.; FARBER M.

JOURNAL OF MICROBIOLOGICAL METHODS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2014 vol. 107 p. 47 - 54

0167-7012

Anaplasma marginale (A. marginale) is an obligate intracellular bacterium that infects bovine erythrocytes causing extravascular hemolysis and anemia. Many attempts have been made to unravel the cycle of invasion and its relation to the pathogenesis of the disease. However, routine methods such as thin blood smear examination fail to provide an accurate description of the progression of the infection. In fact, bacterial number within erythrocytes has been only reported in transmission electron microscopy studies. In the present work, we combine SYTO16 labelling of parasitized cells with the statistical power of flow cytometry to study the evolution of erythrocyte infection during bovine anaplasmosis. Two animals were experimentally inoculated with A. marginale. Fluorescence emission histograms revealed that the arrangement of infected erythrocytes with respect to fluorescence intensity was non random and two patterns of distribution were found to alternate within a 24 h period. Treatment with oxytetracycline prevented this cycling. At this point the distribution of infected erythrocytes displayed four mean fluorescence intensity peaks that correlate with a putative bacterial number of 2n, with n=0,1,2,3. This evidence sugests that SYTO16-flow cytometry is a suitable tool to distinguish between erythrocytes harboring 1, 2, 4 and 8 bacteria. Additionally, red blood cell dynamics during the period of maximum anemia is presented. The analysis of SYTO16 positive cells sustains the hypothesis that newly released macrocytes are not infected by A. marginale.