ABSTRACT
To date, there is little information concerning the epidemiological situation of classical swine fever (CSF) in the Americas. Besides summarizing the available data, genotyping of isolates from outbreaks in domestic pigs in several countries of South and Central America was performed. For this, a 190 base fragment of the E2 envelope glycoprotein gene was used. European strains and isolates, and historical isolates from the United States (US) were included for comparison. In contrast to the situation in most parts of Europe, where group 2 isolates predominate, it was found that all the isolates from the American continent analyzed belonged to group 1 and were further resolved into three subgroups. The Cuban isolates clustered in subgroup 1.2, whereas the isolates from Honduras and Guatemala clustered in subgroup 1.3. The remaining isolates from Argentina, Brazil, Colombia and Mexico generated four poorly resolved clusters in subgroup 1.1, together with the vaccine strains, with historical European and US isolates, and with a recent Russian isolate. While the vaccine strains and the historical European isolates formed a relatively distinct cluster, one of the US isolates clustered together with the Mexican, and another one with Colombian isolates. Historically, CSF (hog cholera) was observed almost simultaneously in the US and in Europe in the first half of the 19th century, and its origin remains a matter of discussion. Our results showed that the US isolates are closely related to isolates from South America, while appearance of isolates in Cuba on one hand and in Honduras and Guatemala on the other hand, seems to have been due to unrelated events. This allows to speculate that at least in the American continent, CSF virus may have appeared independently in several regions, and spreading may have been a secondary effect.
Subject(s)
Classical Swine Fever Virus/genetics , Classical Swine Fever Virus/isolation & purification , Classical Swine Fever/epidemiology , Classical Swine Fever/virology , Disease Outbreaks/veterinary , Animals , Central America/epidemiology , Classical Swine Fever Virus/classification , DNA, Viral/chemistry , Genotype , Molecular Epidemiology , Molecular Sequence Data , Phylogeny , Sequence Analysis, DNA , South America/epidemiology , Sus scrofa/virology , Viral Envelope Proteins/geneticsABSTRACT
The genetic diversity of classical swine fever virus (CSFV) was studied by RT-PCR amplification and sequencing of a 409 bp fragment of the NS5B polymerase region. A total of 106 viruses isolated from 20 countries over a period of 52 years (1945-1997) were included in the phylogenetic study. The results showed that the viruses could be divided into two main groups. Group 1 consisted of Asian and South American isolates from the 1980s, as well as of old European and American isolates. Group 2 consisted mostly of recent European viruses from the 1980s and 1990s, and was further divided into three subgroups largely according to geographic origin and/or year of isolation. Five 1997 CSFV isolates from Germany, Netherlands and Italy clustered together indicating a common origin for these outbreaks, but two other 1997 isolations in different regions of Germany are likely due to different epidemiological events. The results show that the NSSB region of the genome gives a good resolution for phylogenetic studies of CSFV. Molecular epidemiology based on nucleotide sequence diversity is a useful tool for tracing virus spread and for developing disease control strategies.
Subject(s)
Classical Swine Fever Virus/genetics , Classical Swine Fever/virology , Animals , Asia/epidemiology , Classical Swine Fever/epidemiology , Classical Swine Fever Virus/classification , Classical Swine Fever Virus/isolation & purification , Europe/epidemiology , Genetic Variation , Genome, Viral , Molecular Sequence Data , Phylogeny , Polymerase Chain Reaction , RNA, Viral/analysis , South America/epidemiology , SwineABSTRACT
O trabalho teve por objetivo avaliar a sensibilidade e a especificidade de um teste imunoenzimático competitivo, empregando como conjugado os anticorpos monoclonais BM-38 e BM-40, no diagnóstico sorológico da brucelose bovina. Foram examinados 74 soros de bovinos dos quais havia sido isolada Brucella abortus e 2.118 soros de bovinos procedentes de rebanhos livres de brucelose e que apresentaram resultado negativo quando submetidos ao teste Rosa Bengala. O teste imunoenzimático competitivo, usando qualquer dos dois conjugados, foi capaz de revelar a presença de anticorpos contra o lipopolissacáride bacteriano em todos os soros de bovinos infectados, o que resulta em uma sensibilidade de 100 por cento. A especificidade do teste usando o conjugado BM-38 foi de 98,82 por cento e usando o conjugado BM-40, foi de 99,95 por cento. Estes resultados indicam que o teste imunoenzimático competitivo, principalmente ao se empregar o conjugado BM-40, consiste em um método bastante útil para ser usado como teste confirmatório no diagnóstico sorológico da brucelose bovina
Subject(s)
Animals , Brucellosis, Bovine/diagnosis , Cattle , Cattle Diseases/diagnosis , Immunoenzyme TechniquesABSTRACT
The purpose of this work was to evaluate the sensitivity and the specificity of a competitive enzyme immunoassay, using as conjugate the monoclonal antibodies BM-38 and BM-40, in the serodiagnosis of bovine brucellosis. Seventy-four sera from culture-positive cattle and 2,118 cattle sera from herds free from brucellosis and negative to the Rose Bengal plate test were examined. The competitive enzyme immunoassay, using any of the two conjugates, was able to reveal the presence of antibodies to Brucella lipopolysaccharide in all of the 74 sera of the infected cattle, resulting in a sensitivity of 100%. The specificity of the test using the conjugate BM-38 was 98.82% and using the conjugate BM-40 was 99.95%. These results indicated that the competitive enzyme immunoassay, mainly when using the conjugate BM-40, consists in a technique very useful in the confirmation of the serological diagnosis of bovine brucellosis.
O trabalho teve por objetivo avaliar a sensibilidade e a especificidade de um teste imunoenzimático competitivo, empregando como conjugado os anticorpos monoclonais BM-38 e BM-40, no diagnóstico sorológico da brucelose bovina. Foram examinados 74 soros de bovinos dos quais havia sido isolada Brucella abortus e 2.118 soros de bovinos procedentes de rebanhos livres de brucelose e que apresentaram resultado negativo quando submetidos ao teste Rosa Bengala. O teste imunoenzimático competitivo, usando qualquer dos dois conjugados, foi capaz de revelar a presença de anticorpos contra o lipopolissacáride bacteriano em todos os soros de bovinos infectados, o que resulta em uma sensibilidade de 100%. A especificidade do teste usando o conjugado BM-38 foi de 98.82% e usando o conjugado BM-40 foi de 99,95%. Estes resultados indicam que o teste imunoenzimático competitivo, principalmente ao se empregar o conjugado BM-40, consiste em um método bastante útil para ser usado como teste confirmatório no diagnóstico sorológico da brucelose bovina.