Use of Leptospira spp. strains isolated in Brazil in the microscopic agglutination test applied to diagnosis of leptospirosis in cattle herds in eight brazilian states

Sarmento A.M.C., Azevedo S.S., Morais Z.M., Souza G.O., Oliveira F.C.S., Goncales A.P., Miraglia F. & Vasconcellos S.A. 2012. [Use of Leptospira spp. strains isolated in Brazil in the microscopic agglutination test applied to diagnosis of leptospirosis in cattle herds in eight brazilian states.] Emprego de estirpes Leptospira spp. isoladas no Brasil na microtecnica de soroaglutinacao microscopica aplicada ao diagnostico da leptospirose em rebanhos bovinos de oito estados brasileiros. Pesquisa Veterinaria Brasileira 32(7);601-606. Universidade de Sao Paulo, Faculdade de Medicina Veterinaria e Zootecnia, Departamento de Medicina Veterinaria Preventiva e Saude Animal, Av. Prof. Dr. Orlando Marques de Paiva 87, Sao Paulo, SP 05508-270, Brazil. E-mail: savasco@usp.br The aim of this study was to investigate the adequacy of the use of autochthonous strains of leptospires isolated in Brazil, added to antigen collection of the microscopic agglutination test (MAT) applied to the diagnosis of bovine leptospirosis. By means of non-probability sampling, 109 farms and 9,820 cattle, females at reproductive age were chosen from 85 municipalities in the states of Goias, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Parana, Rio Grande do Sul, Santa Catarina and Sao Paulo. Among the 9,820 examined animals, 5,806 (59.12%) were reactants at MAT for at least one serovar using the 23 reference serovars. Employing the collection of reference serovars and the ten autochthonous strains, 6,400 (65.24%) reactants and significant difference (p=0.001) was found. The most probable serovars identified by the collection of reference antigens were Hardjo (43.03%), Shermani (20%), Wolfi (9.96%), Grippothyphosa (5.42%) and Pomona (4.28%). With the collection amplified with the ten strains isolated in Brazil, the most probable serovars were Hardjo (31%), Guaricura-M4/84 (22.50%), Shermani (15.43%), Wolffi (4.76%), Grippothyphosa (3.71%) and Autumnalis (3.24%). The serovar Guaricura, strain M4/84, isolated from bovines and buffaloes in the State of Sao Paulo, was ranked as one of the three most probable serovars in the states of Goias, Mato Grosso, Mato Grosso do Sul, Minas Gerais and Sao Paulo. The addition of autochthonous strains to the MAT antigen collection provided the confirmation of the diagnosis of leptospirosis in 594 cattle (6%) which have been classified as non-reactants by the reference collection (p=0.001).

Gametic phase disequilibrium between the syntenic multiallelic HTG4 and HMS3 markers widely used for parentage testing in Thoroughbred horses

Validation of parentage and horse breed registries through DNA typing relies on estimates of random match probabilities with DNA profiles generated from multiple polymorphic loci. Of the twenty-seven microsatellite loci recommended by the International Society for Animal Genetics for parentage testing in Thoroughbred horses, eleven are located on five chromosomes. An important aspect in determining combined exclusion probabilities is the ascertainment of the genetic linkage status of syntenic markers, which may affect reliable use of the product rule in estimating random match probabilities. In principle, linked markers can be in gametic phase disequilibrium (GD). We aimed at determining the extent, by frequency and strength, of GD between the HTG4 and HMS3 multiallelic loci, syntenic on chromosome 9. We typed the qualified offspring (n (1) = 27; n (2) = 14) of two Quarter Bred stallions (registered by the Brazilian Association of Quarter Horse Breeders) and 121 unrelated horses from the same breed. In the 41 informative meioses analyzed, the frequency of recombination between the HTG4 and HMS3 loci was 0.27. Consistent with genetic map distances, this recombination rate does not fit to the theoretical distribution for independently segregated markers. We estimated sign-based D' coefficients as a measure of GD, and showed that the HTG4 and HMS3 loci are in significant, yet partial and weak, disequilibrium, with two allele pairs involved (HTG4*M/HMS3*P, D'(+) = 0.6274; and HTG4*K/HMS3*P, D'(-) = -0.6096). These results warn against the inadequate inclusion of genetically linked markers in the calculation of combined power of discrimination for Thoroughbred parentage validation.