Vet Gazette

Dr. Luiz Bermudez has been awarded an NIH RO1 funded grant for his proposal “Genes associated with M. avium pathogenesis.”

This award is for $2,100,000 over five years, March 2010-February 2015.

• The grant is to study the mechanisms used by Mycobacterium avium to survive and replicate within host macrophages. Mycobacterium avium is a human and animal pathogen, that causes lung and disseminated disease. Mycobacteria live within cytoplasm vacuoles in macrophages, blocking vacuole maturation, by inhibiting acidification and fusion with lysosomes. The group is working in the understanding of mechanisms such as the bacterial-driven modification of the mycobacterial vacuole inside macrophages, making it a suitable environment for replication. The group has found genes/proteins which modify the vacuole membrane content upon cell uptake, as well as suppress the host innate immune response triggered by macrophage’s surveillance sensors. They are also working with a M. avium protein that selectively inhibits endosomic proteins involved in the maturation of the phagosome. They have also discovered bacterial genes associated with the M. avium’s ability to resist the killing mechanism in macrophages. For instance, genes/proteins linked with the bacterial resistance to nitric oxide, antimicrobial peptides and even unknown macrophage killing mechanisms. They are also working in the understanding of how bacteria escapes macrophages once they undergo apoptosis, as a strategy to kill the intracellular aggressor. A combination of cell and molecular biology, biochemistry and genomics to understand pathogenesis.

Dr. Dan Rockey has been awarded an NIH R21 funded grant for his proposal “Analysis of chlamydial recombination in vivo.”

The award is for $402,050 over two years, April 2010-March 2012.

• Although chlamydiae are challenging to work with in the laboratory, one thing they do very well is recombine their chromosomes. What this means is that two  strains of chlamydiae can be mixed together in the laboratory, and they will basically mix and match their genomes. We have identified clinical strains that appear to have recombined in patients, and we are exploring whether or not we can  model this “in vivo recombination” in an animal system. These studies will help us to evaluate the role of individual chlamydial genes in disease, and provide important information about possible vaccine or therapeutic drug targets.

Alpha-tocopherol beta-oxidation localized to rat liver mitochondria. Mustacich D.J., Leonard S.W., Patel N., and Traber M.G. (2009) Free Radic Biol Med, Oct 9. Epub ahead of print.

Presented by Dr. Debbie Mustacich at the Society for Free Radical Biology and Medicine Annual Meeting, November 2009, San Francisco, Calif.

• Approximately 40% of Americans take dietary supplements, including vitamin E (a-tocopherol). Unlike other fat-soluble vitamins, a-tocopherol is not accumulated to toxic levels, even when daily pharmacologic vitamin E doses are administered. In a previous study Dr. Mustacich and her collaborators (Dr. Maret Traber and Scott Leonard) demonstrated that tissue vitamin E levels are tightly regulated, in part via increased hepatic metabolism and excretion that could, theoretically, alter metabolism of drugs, environmental toxins and other nutrients. Given the importance of regulation of vitamin E concentrations in human health, Dr. Mustacich and her colleagues have continued to focus upon elucidating the mechanism of hepatic a-tocopherol metabolism and excretion. Their most recent study is the first to demonstrate that mitochondria are involved in the metabolism of a-tocopherol. This is an important discovery as, to date, scientists have assumed that mitochondria did not play a role in vitamin E metabolism. Based on their findings Dr. Mustacich and her colleagues have proposed a new pathway for vitamin E metabolism that may shed light on the function of vitamin E in human health.

A reliable body condition scoring technique for estimating condition in African buffalo. Ezenwa, V. O., Jolles, A. E., & M. O. Brien. 2009. African Journal of Ecology 47: 476-481.

• Evaluating animal body condition is a necessary component of many ecological studies. In this study, the reliability of a noninvasive body condition scoring technique in African buffalo was evaluated. It compared a body condition score (BCS) based on visual assessment and manual palpation of an animal’s body to two standard metrics of condition widely used in mammals: kidney fat index (KFI) and haematocrit (HCT). BCS was positively and significantly correlated with both KFI and HCT, demonstrating the BCS technique to be a useful method for estimating body condition in buffalo.

Evaluation of hematologic values in free-ranging African buffalo (Syncerus caffer). Beechler, B.,  Ezenwa, V. O.,   Jolles, A. E. 2009. Journal of Wildlife Disease 45: 57-66.

• As part of a large-scale disease screening program, blood samples were collected from 534 African buffalo in South Africa’s Hluhluwe-iMfolozi Park. Sixty-seven of the animals were positive for bovine tuberculosis (TB), allowing for comparisons between TB-positive and TB-negative animals. Blood values were compared to those reported for captive buffalo, American bison and cattle. Blood values for free-ranging buffalo differed from cattle and bison values and even from values for captive buffalo, emphasizing the need to use species-specific data when interpreting blood values, and important differences in hematology between captive and free-living animals. TB-positive animals had a slight lymphopenia compared to TB-negatives. Animal age, sex, herd affiliation and season all stongly affected hematology, illustrating how “normal” hematologic values in wild animals vary throughout their lives and with environmental conditions.