ABSTRACT
@#<p><strong>BACKGROUND:</strong> Domestic animals are known to be either maintenance or accidental hosts of Leptospira. Determination of seroprevalence of leptospirosis among these animals is of great importance due to their close association with humans, economic loss as well as the public and veterinary health problems caused by the said zoonosis.</p><p><strong>OBJECTIVE:</strong> This study aimed to determine the seroprevalence of leptospirosis among water buffaloes, pigs, and dogs in selected areas in the Philippines.</p><p><b>METHODS:</b> Microscopic agglutination test (MAT) was used to test for leptospirosis. Testing was done from January 2007 to August 2008.</p><p><strong>RESULTS:</strong> With the cut-off titer set at 1:80, the MAT-positivity rates were 82%, 67%, and 79% for 190 water buffaloes, 45 pigs, and 106 dogs, respectively. The most common prevailing serovars detected were Hardjo, Tarassovi, and Hebdomadis for water buffaloes; Semaranga, Grippotyphosa, and Patoc for pigs; and, Manilae, Patoc, and Autumnalis for dogs. MAT-positivity rates among these animals in terms of age (except for water buffaloes), sex and sample collection sites were not statistically significant. No Leptospira was isolated from the blood, urine, and kidney samples of these animals.</p><p><strong>CONCLUSION:</strong> Results indicate a high seroprevalence of leptospirosis among the animals studied and that several pathogenic leptospires are causing infection in these animals.</p>
Subject(s)
Animals , Seroepidemiologic Studies , Leptospirosis , Swine , PhilippinesABSTRACT
<p><b>OBJECTIVE</b>To understand the mechanism of invasion by Legionella dumoffii.</p><p><b>METHODS</b>The L. dumoffii strain Tex-KL was mutated using the Tn903 derivative, Tn903dIIlacZ. After screening 799 transposon insertion mutants, we isolated one defective mutant. We then constructed the gene-disrupted mutant, KL16, and studied its invasion of and intracellular growth in HeLa and A549 cells, and in A/J mice survival experiments. The structure of traC-traD operon was analyzed by RT-PCR.</p><p><b>RESULTS</b>The transposon insertion was in a gene homologous to Salmonella typhi traC, which is required for the assembly of F pilin into the mature F pilus structure and for conjugal DNA transmission. Results from RT-PCR suggested that the traC-traD region formed an operon. We found that when the traC gene was disrupted, invasion and intracellular growth of L. dumoffii Tex-KL were impaired in human epithelial cells. When mice were infected by intranasal inoculation with a traC deficient mutant, their survival significantly increased when compared to mice infected with the wild-type strain..</p><p><b>CONCLUSION</b>Our results indicated that the traC-traD operon is required for the invasion and intracellular growth abilities of L. dumoffii Tex-KL in epithelial cells.</p>