RESUMO
In several parts of China, there have been a large number of pseudorabies (PR) outbreaks which have devastated many swine farms even though the herds had been previously immunized with gE-deleted vaccines (Bartha-K61). The emergence of these outbreak-associated PRV strains might indicate that Bartha-K61 vaccine could not provide effective protection and poses challenges for current serologic diagnostics of anti-PRV antibodies. Here, we performed phylogenetic analyses based on partial gE, gB, and gC genes to provide information about the molecular epidemiology, diagnostics, and immune protection in these outbreak-associated PRV strains. Our results indicated that the maximal nucleotide sequence divergence for gE, gB, and gC genes are 1.7, 0.4, and 2.7 % within the cluster where outbreak-associated PRV strains were located, and are 2.3, 2.7, and 7.6 % with other clusters in the phylogenetic trees, respectively. Phylogenetic analyses revealed that gE, gB, and gC genes of the twelve outbreak-associated PRV strains clustered to a relatively independent branch of the tree, and evolved from the same ancestor with strains Ea-China-1999, Fa-China-2001, and BJ-China-2008. The genetic relationship between these outbreak-associated PRV strains and strain Bartha is not close which may genetically explain the emergence of PR outbreaks in Bartha-K61-vaccinated swine farms. We suggest that these outbreak-associated PRV strains originate from earlier strains in local regions in China.
Assuntos
Surtos de Doenças , Variação Genética , Herpesvirus Suídeo 1/classificação , Pseudorraiva/epidemiologia , Pseudorraiva/virologia , Doenças dos Suínos/epidemiologia , Doenças dos Suínos/virologia , Animais , China/epidemiologia , Análise por Conglomerados , DNA Viral/química , DNA Viral/genética , Genótipo , Herpesvirus Suídeo 1/genética , Herpesvirus Suídeo 1/isolamento & purificação , Epidemiologia Molecular , Dados de Sequência Molecular , Filogenia , Análise de Sequência de DNA , Homologia de Sequência , Suínos , Proteínas Virais/genéticaRESUMO
An immunochromatographic strip was developed for the serological detection of pseudorabies virus (PRV) in swine. In the strip, the expressed protein of gB, one of the glycoproteins of PRV, labeled with colloidal gold, was used as the detector; staphylococcal protein A and swine anti-pseudorabies virus antibody were blotted on nitrocellulose membrane for the test and control lines, respectively. The specificity of the strip was 98.1%, and the sensitivity of the strip with reference anti-PRV serum was 96.0%. Swine serum samples (296) were collected to evaluate the characteristics of the strip in comparison with an existing commercial kit. The agreement was 93.6%. Furthermore, the dipstick assay based on the strip is rapid (5 min) and easy to perform with no requirement of professional skills, reagents, or equipment. This suggests that the immunochromatographic strip is an acceptable alternative for use in clinical laboratories lacking specialized equipment and for field diagnosis.