Molecular and Pathological Characterization of Classical Swine Fever Virus Genotype 2 Strains Responsible for the 2013–2018 Outbreak in Colombia

Abstract

Classical swine fever (CSF) is a highly contagious transboundary viral disease of domestic and wild pigs. Despite mass vaccination and continuous eradication programs, CSF remains endemic in Asia, some countries in Europe, the Caribbean and South America. Since June 2013, Northern Colombia has reported 137 CSF outbreaks, mostly in backyard production systems with low vaccination coverage. The purpose of this study was to characterize the virus responsible for the outbreak. Phylogenetic analysis based on the full-length E2 sequence shows that the virus is closely related to CSF virus (CSFV) genotype 2.6 strains circulating in Southeast Asia. The pathotyping experiment suggests that the virus responsible is a moderately virulent strain. The 190 nucleotide stretch of the E2 hypervariable region of these isolates also shows high similarity to the CSFV isolates from Colombia in 2005 and 2006, suggesting a common origin for the CSF outbreaks caused by genotype 2.6 strains. The emergence of genotype 2.6 in Colombia suggests a potential transboundary spread of CSFV from Asia to the Americas, complicating the ongoing CSF eradication efforts in the Americas, and emphasizes the need for continuous surveillance in the region.

Oral Fluids for the Early Detection of Classical Swine Fever in Commercial Level Pig Pens

“…It has been eradicated from North America but is endemic in the Caribbean, Central and South America, and Asia. Endemic countries use vaccines to control the disease, and under positive selective pressure resulting from sub-optimal vaccination, CSFV has evolved towards moderately or low-virulent strains [ 1 , 22 , 27 ]. Such strains do not cause typical signs of the disease for a prolonged period of time, and therefore, can spread within and between herds unnoticed.…”

“…They developed viremia on 15 and 16 dpc, indicating they were only around 2 weeks post-infection when the study ended. During a previous pathogenesis study [ 22 ] using the same strain, only one out of six pigs that were oronasally inoculated had seroconverted by 22 dpi.…”

“…In biosafety level 3 animal pens at the National Centre for Foreign Animal Disease (NCFAD), in Winnipeg, Canada, two independent animal experiments were conducted, each with 25 pigs. Experiment #1 was conducted with the moderately-virulent CSFV strain Pinillos [ 22 ] and experiment #2 with the highly-virulent CSFV Koslov [ 23 ]. The use of animals was approved by the Animal Care Committee at the Canadian Science Centre for Human and Animal Health under the Animal Use Document number C-21-006, and all procedures involving the animals were in compliance with the Canadian Council for Animal Care guidelines.…”

“…As the moderately-virulent strain, we used CSFV Pinillos, a genotype 2.6 strain isolated from Colombia in 2016. It is believed to have originated in South-East Asia and was responsible for the CSF outbreaks in Colombia since 2005 [ 22 ]. The reference strain CSFV Koslov was used as the highly-virulent strain in our second experiment [ 23 ].…”

Porvac® subunit vaccine induces neutralizing antibodies against all three main classical swine fever virus genotypes

“…The different sub-genotypes of CSFV follow a speci c geographical distribution [12]. Six sub-genotypes have been described for genotype 1 (1.1 to 1.6), three for genotype 2 (2.1 to 2.3), and four for genotype 3 (3.1 to 3.4) [4,15]. Recently, a new classi cation system, dividing CSFV strains into ve genotypes (one to ve) has been proposed to accommodate the strain known as "congenital myoclonus" (Great Britain/1964) and two strains from Korea (KR/1998, KR/1999).…”