Infection characteristics of porcine circovirus type 2 in different herds from intensive farms in China, 2022

Abstract

IntroductionPorcine circovirus type 2 (PCV2) is the primary etiological agent of porcine circovirus diseases (PCVD), which are widespread in most pig herds, causing huge economic losses in the global pig industry. Therefore, it is critical to assess the infection characteristics of PCV2 in different swine herds to develop effective strategies against PCVD.MethodsIn this study, routine diagnostic and monitoring protocols were used to collect 12,714 samples from intensive farms in China, and PCV2 was tested for by qPCR to determine positivity rates and viral loads in samples from different herds and materials.ResultsPCV2 was found to be prevalent throughout China, and fattening farms had higher positivity rates than breeding farms. The PCV2 positivity rates in breeding farms in Southern China were higher than those in Northern China. Growing–finishing pigs demonstrated the highest positivity rate in the tested samples, while pre-weaning piglets and adult sows had the lowest. Meanwhile, samples with viral loads exceeding 106 copies/mL in growing–finishing pigs had 27.2% positivity, compared to 1.9% and 3.3% in sows and piglets, respectively. The results of the viral loads in the serum samples followed a similar trend.DiscussionThe findings reveal that PCV2 circulates in different herds from intensive farms, with positivity increasing from pre-weaning to growing–finishing herds. It is urgent to develop effective strategies to reduce PCV2 positivity in growing–finishing herds and prevent viral circulation among pigs.

Assessment of sow herd frequency of PCV-2 using placental umbilical cord serum and serology in 18 breeding farms in Brazil

“…The use of PUCS as a sample to detect PCV-2 has a high sensitivity, similar to that of colostrum and pre-suckling serum and higher to that of sow serum and processing fluids ( 23 , 26 ). PUCS was used to determine prevalence of PCV-2 infection as a diagnostic specimen in some studies ( 16 , 24 ) and also to evaluate the effects of sow vaccination against PCV-2 in different stages of the production cycle ( 22 ). Therefore, the aim of this study was to assess the frequency of viremic newborn piglets for PCV-2 using qPCR based on PUCS and to determine immune status of sows using serology (ELISA).…”

“…Blood sampling soon after farrowing has been used to assess PCV-2 serology in sows (10). Additionally, placental umbilical cord serum (PUCS), pre-suckling piglet serum, umbilical cord tissue, colostrum, and fetal tissues have been used to determine sow herd PCV-2 prevalence through the measure of PCV-2 viremia (8,15,(22)(23)(24)(25). The use of PUCS as a sample to detect PCV-2 has a high sensitivity, similar to that of colostrum and pre-suckling serum and higher to that of sow serum and processing fluids (23,26).…”