My area of expertise is ultrastructural studies of bacteria (especially rickettsia, ehrlichia, anaplasma, and chlamydia), viruses and protozoa pathogenic for humans and animals and their interaction with the host cells at the ultrastructural level in patients and in model systems. I have more than 50 years of experience in electron microscopy and its different techniques. My expertise in this area is documented in more than 250 publications in peer-reviewed journals. During these years I have collaborated with many investigators nationally and internationally and trained more than 70 graduate students, fellows and research scientists in electron microscopy techniques, analysis and interpretation of electron microscopic data.