Replication and virulence in pigs of the first African swine fever virus isolated in China

Abstract

African swine fever (ASF) entered China in August 2018 and rapidly spread across the entire country, severely threatening the Chinese domestic pig population, which accounts for more than 50% of the pig population worldwide. In this study, an ASFV isolate, Pig/Heilongjiang/2018 (Pig/HLJ/18), was isolated in primary porcine alveolar macrophages (PAMs) from a pig sample from an ASF outbreak farm. The isolate was characterized by using the haemadsorption (HAD) test, Western blotting and immunofluorescence, and electronic microscopy. Phylogenetic analysis of the viral p72 gene revealed that Pig/HLJ/18 belongs to Genotype II. Infectious titres of virus propagated in primary PAMs and pig marrow macrophages were as high as 10 7.2 HAD 50 /ml. Specific-pathogen-free pigs intramuscularly inoculated with different virus dosages at 10 3.5 –10 6.5 HAD 50 showed acute disease with fever and haemorrhagic signs. The incubation periods were 3–5 days for virus-inoculated pigs and 9 days for contact pigs. All virus-inoculated pigs died between 6–9 days post-inoculation (p.i.), and the contact pigs died between 13–14 days post-contact (p.c.). Viremia started on day 2 p.i. in inoculated pigs and on day 9 p.c. in contact pigs. Viral genomic DNA started to be detected from oral and rectal swab samples on 2–5 days p.i. in virus-inoculated pigs, and 6–10 days p.c. in contact pigs. These results indicate that Pig/HLJ/18 is highly virulent and transmissible in domestic pigs. Our study demonstrates the threat of ASFV and emphasizes the need to control and eradicate ASF in China.

Rapid detection of African swine fever virus using Cas12a-based portable paper diagnostics

“…Primary porcine alveolar macrophages were infected at a multiplicity of infection (MOI) of 0.1 with ASFV, which was isolated from field samples as described previously 43,44 . Cell supernatants were collected on day 3 after infection.…”

Spread of deadly pig virus in China hastens vaccine research

“…Groups in China are also studying how the virus survives in the host. In February, researchers at the HVRI reported that a strain extracted from the spleen of an infected pig was extremely virulent, resulting in certain death, and efficient at passing from pig to pig 3 .…”

Development of a rapid and sensitive europium (III) chelate microparticle-based lateral flow test strip for the detection and epidemiological surveillance of porcine epidemic diarrhea virus

“…Recently, a lateral flow immunoassay, a well-established and accepted point-of-care testing technique, was used to develop quantitative fluorescent strips with various fluorescent reporters, which include colloidal gold, fluorescent dyes, quantum dots, and lanthanide chelates [2,3,27,28]. The first case of African swine fever virus (ASFV) infection in China was reported on August 3, 2018 [26]. By July 10, 2019, almost all provinces in China had reported the appearance of ASFV (http://www.oie.int/).…”