Saturday, 24 August 2013

New Chinese research connects Circovirus and Classical Swine Fever

For many years, we have publicly connected the secret 1999 English outbreak of Circovirus (PCV2) (usually called PMWS & PDNS then) to the devastating 2000 Classical Swine Fever (CSF) and almost simultaneous 2000-2001 Foot and Mouth Disease (FMD) outbreaks. 

The pigs were sick before CSF (or FMD) arrived. The devastating CSF and FMD were the second and third epidemics in a sequence of three. Foot and Mouth cost billions and even caused the postponement of a General Election. 

That, with the secrecy, gave rise to compensation issues for a non-notifiable disease. Any possible connection was deliberately ignored and anyone kicking up, over the obvious fabrications planted in the media, was harassed.

Now, thirteen long years have passed, and putting aside the underlying British constitutional  political, commercial and monetary scandals, the Chinese produce science that tells us that pigs with Circovirus are more likely to get CSF and make the resultant epidemic harder to control.

We know. We were there, with pigs at the epicentre, when it happened for real for the first time. 

We had to stand and watch the most senior British government veterinarians fake tests and threaten complainants and witnesses to Parliament and OLAF, the serious fraud squad of the EU.

Circovirus, little understood then, was much more dangerous than anyone was prepared to admit, both directly and by interference with the immune system.

It was also a prime driver of human antibiotic resistance:  the antibiotics were needed to cope with co-infections.

The science is complicated, but  the the last paragraph of the abstract is quite clear.

 Pig333 abstract in full here

Porcine circovirus type 2 (PCV2) infection decreases the efficacy of an attenuated classical swine fever virus (CSFV) vaccine


Yu-Liang Huang, Victor Fei Pang, Chun-Ming Lin, Yi-Chieh Tsai, Mi-Yuan Chia, Ming-Chung Deng, Chia-Yi Chang and Chian-Ren Jeng. Porcine circovirus type 2 (PCV2) infection decreases the efficacy of an attenuated classical swine fever virus (CSFV) vaccine. Veterinary Research 2011, 42:115. doi:10.1186/1297-9716-42-115
The Lapinized Philippines Coronel (LPC) vaccine, an attenuated strain of classical swine fever virus (CSFV), is an important tool for the prevention and control of CSFV infection and is widely and routinely used in most CSF endemic areas, including Taiwan.

The aim of this study was to investigate whether PCV2 infection affects the efficacy of the LPC vaccine. Eighteen 6-week-old, cesarean-derived and colostrum-deprived (CDCD), crossbred pigs were randomly assigned to four groups.The pigs in groups 1 and 2 were intranasally inoculated with 0.5 mL of PCV2 in each nostril and were intramuscularly injected with 1 mL of PCV2 at 0 dpi (a total dose of 105.3 TCID50per pig). The pigs in groups 1 and 3 were intramuscularly injected with 1 dose of LPC vaccine/pig at 12 dpi. Therefore, all pigs were challenged with 1 mL of CSFV (ALD strain)/pig by intramuscular injection at 27 dpi (a total dose of 106.8 TCID50 per pig). Clinical monitoring was recorded daily, and rectal temperature and sample collection of blood, saliva, and feces were taken every 3 days until 45 dpi. All surviving pigs were necropsed at 45 dpi.

Following CSFV challenge, the LPC-vaccinated pigs pre-inoculated with PCV2 showed transient fever, viremia, and viral shedding in the saliva and feces. The number of IgM+, CD4+CD8-CD25+, CD4+CD8+CD25+, and CD4-CD8+CD25+ lymphocyte subsets and the level of neutralizing antibodies against CSFV were significantly higher in the animals with LPC vaccination alone than in the pigs with PCV2 inoculation/LPC vaccination. In addition, PCV2-derived inhibition of the CSFV-specific cell proliferative response of peripheral blood mononuclear cells (PBMCs) was demonstrated in an ex vivo experiment.

These findings indicate that PCV2 infection decreases the efficacy of the LPC vaccine. This PCV2-derived interference may not only allow the invasion of wild-type CSFV in pig farms but also increases the difficulty of CSF prevention and control in CSF endemic areas.