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Biological Health Hazard – (Panzootic infection) Classical Swine Fever, New (CSFV) subgenotype: China

2017/06/01

CLASSICAL SWINE FEVER – CHINA: NEW SUBGENOTYPE
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Published Date: 2017-06-01 17:21:02
Subject: PRO/AH> Classical swine fever – China: new subgenotype
Archive Number: 20170601.5077770

Date: Wed 31 May 2017, 6:00 AM EDT
Source: Farm Journal, Pork Network [edited]

Reports from China say a new subgenotype of classical swine fever virus (CSFV) is responsible for recent outbreaks in that country, according to the Swine Health Information Center (SHIC). The Center reports that further results show specific antibodies elicited by vaccination of C-strain vaccine could not effectively protect against the new strains of CSF found in China, leading to the new cases.

“An article in the Veterinary Microbiology journal (2017; 201: 154-161) highlights an emerging disease issue occurring in China,” said the article in the SHIC newsletter. “For decades, CSF has been controlled in China due to extensive, mandatory vaccination with C-strain-based commercial vaccines. Recent frequent CSF outbreaks in this Asian nation have raised concern internationally and the Swine Health Information Center is monitoring developments closely.”

SHIC representatives say these discoveries create the need for additional studies, using field situations, to evaluate both the virus strains and vaccines to combat outbreaks.

Read the entire paper on this subject from the Veterinary Microbiology journal http://www.sciencedirect.com/science/article/pii/S0378113517300561 [abstract; for the full paper, subscription required].

SHIC serves as an important vehicle to monitor swine pathogens on a global level and relay information on threats to the global herd.

[byline: JoAnn Alumbaugh]

communicated by:
ProMED-mail
<promed@promedmail.org>

[The addressed paper is: Luo Y, Ji S, Lei JL, et al. Efficacy evaluation of the C-strain-based vaccines against the subgenotype 2.1d classical swine fever virus emerging in China. Vet Microbiol. 2017;201:154-161. doi: 10.1016/j.vetmic.2017.01.012. Epub 2017 Jan 17.

Abstract
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“Classical swine fever (CSF) is a devastating infectious disease of pigs caused by classical swine fever virus (CSFV). The disease has been controlled following extensive vaccination with the lapinized attenuated vaccine C-strain for decades in China. However, frequent CSF outbreaks occurred recently in a large number of C-strain-vaccinated pig farms in China and a new subgenotype 2.1d of CSFV has been reported to be responsible for the outbreaks. Here we analyzed the molecular variations and antigenic differences among the C-strain-based commercial vaccines of different origins from different manufacturers in China, and reevaluated the vaccines against the emerging subgenotype 2.1d strain of CSFV. The results showed that the C-strain adapted to the continuous ST cell line (CST) contain a unique M290K variation on the E2 protein, compared to those of primary BT cells (CBT) or rabbit origin (CRT) and the traditional Cstrain sequences available in the GenBank database. Serum neutralization test revealed the antigenic differences between CST and CBT or CRT. Notably, the neutralizing titers of porcine anti-C-strain sera against the CSFV isolate of subgenotype 2.1d were significantly lower than those against C-strain or Shimen strain. The C-strain-vaccinated, subgenotype 2.1d HLJZZ2014 strain-challenged pigs did not show any clinical signs and all survived. However, these pigs displayed mild pathological and histological lesions, and the CSFV viral RNA was detected in the various tissue and blood samples. Taken together, the C-strain-based vaccines of different origins showed molecular variations and antigenic differences, and could provide clinical but not pathological and virological protection against the subgenotype 2.1d CSFV emerging in China. Further investigation is needed to comprehensively assess the efficacy of C-strain of different doses against the subgenotype 2.1d CSFV.”

Classical swine fever (CSF), also known as hog cholera, is a contagious viral disease of pigs, including wild boar. The causative virus is a member of the genus _Pestivirus_ of the family _Flaviviridae_, and is closely related to the viruses of bovine viral diarrhoea and border disease. There is only one serotype of CSF virus (CSFV).

For the chapter 2.8.3 “Classical swine Fever” in OIE’s terrestrial Manual, adopted by the General Assembly in May 2014, please refer to http://www.oie.int/fileadmin/Home/eng/Health_standards/tahm/2.08.03_CSF.pdf. – Mod.AS

A HealthMap/ProMED-mail map can be accessed at: http://healthmap.org/promed/p/155.]

See Also

2015

Classical swine fever & Actinobacillus pleuropneumoniae – China: (SX) mixed infection 20151230.3902180

2006

Swine fever, classical – China (Beijing), mixed infection susp 20061223.3592
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Source:
A ProMED-mail post
ProMED-mail is a program of the International Society for Infectious Diseases


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