为研究高致病性猪繁殖与呼吸综合征病毒（high pathogenic-porcine reproductive and respiratory syndrome virus,HP-PRRSV）感染猪后其血清病毒载量和体重增长的变化规律，以大白猪和通城猪的高代横交群体中72头健康仔猪为研究对象进行HP-PRRSV人工感染，观察临床症状，并在感染前和感染后第4、7、11、14、21、28、35 天进行空腹采血、体重称量、血清分离以及病毒载量检测。结果显示：在感染第0~4天体重增长速度缓慢，第4~21天体重一直呈负增长、第7~11天体重减少量达最大值、第21~35天体重呈正增长；病毒载量在感染第4天达到峰值并持续到第7天，第7~35天病毒载量逐渐下降至6.62 lg copies/mL；感染第7天出现死亡，死亡个体主要集中在7~14 d，在第10天出现死亡高峰，第19天后基本稳定；依据第14天存活与否，将试验猪分为抗病和易感2个组，抗病组的病毒载量在第4、7、11天均显著低于易感组（P<0.05），该组的体重增长量在第4~7、7~11、11~14天均显著高于易感组（P<0.05）。上述结果表明，在感染过程中体重增长和病毒载量2个性状可作为预测PRRS抗病性的指示性状。
High pathogenic-porcine reproductive and respiratory syndrome (HP-PRRS) has caused great economic losses to pig industry in China. In order to study the changes of serum viremia and body weight gain in pigs after HP-PRRSV (HP-PRRS Virus) infection,72 healthy piglets from a large white pigs and Tongcheng pigs crossed population were selected and infected with HP-PRRSV. The clinical symptoms were observed,weight was measured,blood samples were collected,serum was separated and viremia was measured on 0,4,7,11,14,21,28,35 dpi (days post infection). The results showed that the growth rate of body weight was slow at 4 dpi,the body weight increased negatively from 4 to 21 dpi,the loss of weight reached the maximum from 7 to 11 dpi,the body weight increased positively and the growth increased gradually from 21 to 35 dpi. Viremia peaked on 4 dpi and lasted until 7 dpi,and decreased to 6.62 log10 copies/mL from 7 dpi to 35 dpi. Death occurred from 7 dpi,and the dead individuals were mainly concentrated from 7 to 14 dpi. The death peak appeared on 10 dpi,and the number of dead individuals was basically stable after 19 dpi. According to the survival on 14 dpi,the pigs were divided into two groups:disease-resistant and susceptible group. The viremia of the disease-resistant group was significantly lower than that in the susceptible group on 4,7,11 dpi (P<0.05),and the weight gain of the disease-resistant group was significantly higher than that of the susceptible group on 4-7 dpi,7-11 dpi,and 11-14 dpi (P<0.05). The above results suggested that body weight gain and viremia could be used as indicators to predict the resistance of PRRS.