Immunogenicity and cross reactivity indices of Streptococcus equi subsp. equi strains isolated from cases of Strangles and commercial vaccines/Imunogenicidade e indices de reatividade cruzada de cepas de Streptococcus equi subsp. Equi isoladas de casos de Adenite Equina e vacinas comerciais

• Published in: Ciência rural Vol. 39; no. 5; pp. 1459 - 1464
• Main Authors: de Moraes, Carina Ma, Sa e Silva, Mariana, Castagna de Vargas, Agueda Palmira, Wayne Nogueira, Carlos Eduardo, Pereira Leivas Leite, Fabio, Gil-Turnes, Carlos
• Format: Journal Article
• Language: English; Spanish
• Published: Universidade Federal de Santa Maria 01-08-2009
• Subjects: Adenite Eqüina; cross reactivity indices; horse Strangles; Streptococcus equi subsp. equi; vaccines; Vacinas; Índice de Reatividade Cruzada
• ISSN: 0103-8478; 1678-4596

Horse Strangles appears frequently in animals vaccinated with commercial bacterins in Rio Grande do Sul, Brazil. Aiming to know the antigenic relationships of strains recovered from sick animals among them and with two vaccines profusely used in the state, bilateral cross reactivity indices (CRI) were estimated. In addition, the immunogenicity of vaccines prepared with field isolates and commercial vaccines was tested in mice. Antibody titers were measured by ELISA and expressed as seroconversions. Thirteen strains of Streptococcus equi subsp. equi, nine classified biochemically as typical and other four as atypical strains, were recovered from 35 sick horses belonging to 10 herds of Rio Grande do Sul, Brazil. The strains recovered from sick horses showed very close CRI, suggesting antigenic homogeneity among them, but not with the vaccinal strains. A vaccine produced with an atypical strain induced the highest seroconversion, 9.4, while two produced with typical strains were poorly-immunogenic. The commercial vaccines were less immunogenic than five and four vaccines produced with field strains, inducing seroconversions of 2.6 and 3.8, respectively. Key words: horse Strangles, Streptococcus equi subsp. equi, cross reactivity indices, vaccines. A Adenite Equina e frequente em animais vacinados com bacterinas comerciais no Rio Grande do Sul. Com o objetivo de determinar as relacoes antigenicas entre cepas isoladas de casos clinicos e duas vacinas amplamente utilizadas no Estado, foram determinados os indices de reatividade cruzada bilateral (IRC) entre elas. Tambem foi determinada a imunogenicidade em camundongos de vacinas preparadas com cepas de campo e de vacinas comerciais. Os titulos de anticorpos foram determinados por ELISA e expressos como soroconversao. Foram isoladas 13 cepas de Streptococcus equi subsp. equi de 35 casos clinicos de Adenite Equina em 10 diferentes rebanhos do Rio Grande do Sul, Brasil, das quais nove foram classificadas bioquimicamente como tipicas e outras quatro como atipicas. As cepas de campo apresentaram elevada reatividade cruzada, sugerindo homogeneidade antigenica entre elas, mas nao com as cepas vacinais. Uma vacina produzida com cepa atipica induziu soroconversao de 9.4, enquanto duas vacinas produzidas com cepas tipicas foram pouco imunogenicas. As vacinas comerciais induziram soroconversoes de 2.6 e 3.8, menores que quatro e cinco vacinas produzidas com cepas de campo, respectivamente. Palavra-chave: Adenite Equina, Streptococcus equi subsp. equi, Indice de Reatividade Cruzada, Vacinas.