June 14, 2010

 

Belgian researchers discover new PRRS sub-type virus

 

 

In a new research, a group of researchers from Ghent University in Belgium has discovered the pathogenesis and antigenic characterisation of a new East European sub-type 3 PRRS virus isolate.

 

Researchers explain that the PRRS virus (PRRSV) is divided into a European and North American genotype. East European PRRSV isolates have been found to be of the European genotype but form different sub-types.

 

In the present study, PRRSV was isolated from a Belarusian farm with reproductive and respiratory failure and designated 'Lena'. Analyses revealed that Lena is a new East European sub-type 3 PRRSV isolate. The main purpose of this investigation was to study the pathogenesis and antigenic characteristics of the PRRS virus (Lena).

 

Results showed obvious clinical and virological differences between the animals inoculated with a recent European sub-type 1 PRRSV isolate (Belgium A) and animals inoculated with PRRSV (Lena). Three out of six pigs inoculated with PRRSV (Belgium A) had anorexia and low fever at three, four and five days post-inoculation. High fever, anorexia and depression were prominent signs in most pigs inoculated with PRRSV (Lena) between two and 28 days post-inoculation. Four pigs out of ten died during the experiment.  Arcanobacterium pyogenes was isolated from lungs of one animal that died, and Streptococcus suis was isolated from lungs of one animal that was euthanised.

 

The difference in viral titres in sera from PRRSV (Belgium A) and PRRSV (Lena)-infected pigs was statistically significant. The highest viral titres in sera ranged from 104.8 to 106.1 TCID50/ml for PRRSV (Lena) whereas they ranged from 103.1 to 104.8 TCID50/ml for PRRSV (Belgium A).

 

Additionally, the replication of PRRSV (Lena) was further studied in depth. Viral titres ranged from 102.5 TCID50/100mg to 105.6 TCID50/100mg in nasal secretions between three and 14 days post-inoculation and from 102.8 TCID50/100mg to 104.6 TCID50/100mg in tonsillar scrapings between three and 21 days post-inoculation.