Anses - laboratoire de Ploufragan-Plouzané, BP53, 22440, Ploufragan, France.
Vet Res. 2012 Oct 12;43(1):69. doi: 10.1186/1297-9716-43-69.
The time-dependent transmission rate of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) and the correlation between infectiousness, virological parameters and antibody responses of the infected pigs were studied in experimental conditions. Seven successive transmission trials involving a total of 77 specific pathogen-free piglets were carried out from 7 to 63 days post-inoculation (dpi). A semi-quantitative real time RT-PCR was developed to assess the evolution of the viral genome load in blood and nasal swabs from inoculated and contact pigs, with time. Virus genome in blood was detectable in inoculated pigs from 7 to 77 dpi, whereas viral genome shedding was detectable from nasal swabs from 2 to 48 dpi. The infectiousness of inoculated pigs, assessed from the frequency of occurrence of infected pigs in susceptible groups in each contact trial, increased from 7 to 14 dpi and then decreased slowly until 42 dpi (3, 7, 2, 1 and 0 pigs infected at 7, 14, 21, 28 and 42 dpi, respectively). These data were used to model the time-dependent infectiousness by a lognormal-like function with a latency period of 1 day and led to an estimated basic reproduction ratio, R0 of 2.6 [1.8, 3.3]. The evolution of infectiousness was mainly correlated with the time-course of viral genome load in the blood whereas the decrease of infectiousness was strongly related to the increase in total antibodies.
在实验条件下，研究了猪繁殖与呼吸综合征病毒（PRRSV）的时变传播率，以及感染猪的传染性、病毒学参数和抗体反应之间的相关性。从接种后 7 天到 63 天（dpi），共进行了 7 次连续的传播试验，涉及 77 头无特定病原体的仔猪。开发了一种半定量实时 RT-PCR 来评估感染和接触猪的血液和鼻拭子中病毒基因组负荷随时间的演变，接种猪的血液中可在 7 到 77dpi 检测到病毒基因组，而鼻拭子中从 2 到 48dpi 可检测到病毒基因组脱落。接种猪的传染性，从每个接触试验中易感组感染猪的发生频率评估，从 7 到 14dpi 增加，然后缓慢下降直到 42dpi（7、14、21、28 和 42dpi 分别有 3、7、2、1 和 0 头猪感染）。这些数据用于通过具有 1 天潜伏期的对数正态样函数对时变传染性进行建模，导致估计的基本繁殖比 R0 为 2.6 [1.8, 3.3]。传染性的演变主要与血液中病毒基因组负荷的时间进程相关，而传染性的下降与总抗体的增加密切相关。
