Yoon I J, Joo H S, Goyal S M, Molitor T W
Department of Clinical and Population Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul 55108.
J Vet Diagn Invest. 1994 Jul;6(3):289-92. doi: 10.1177/104063879400600326.
Various conditions were evaluated and modified to improve the sensitivity of the serum neutralization (SN) test for detecting antibody in pigs infected with porcine reproductive and respiratory syndrome virus (PRRSV). Higher SN titers were consistently obtained by the addition of 20% fresh swine serum to the virus diluent and by the use of a permissive cell clone (MARC-145) derived from the MA-104 cell line. Test sera used to assess the SN test were obtained from 2 groups of 3-week-old pigs infected intranasally with PRRSV (MN-1b). Using the modified method, SN antibody was first detected 9-11 days postinoculation (PI), with a peak evident at 11-21 days PI. The antibody subsequently declined, and a second peak was observed between 41 and 45 days PI. The first antibody peak was not observed and the SN antibody was only detectable between 32 and 41 days PI when the test was done with 20% heated swine serum or without supplemental swine serum. The SN antibody during 2-3 weeks PI was found to be sensitive to 2-mercaptoethanol or anti-swine IgM treatment. The SN antibody titers were high when homologous PRRSV isolate was used in the test but were markedly low for heterologous PRRSV isolates. No difference in antibody titers was observed when homologous and heterologous PRRSV isolates were tested by indirect fluorescent antibody assay. These results indicate that the modified SN method is useful in detecting earlier and higher PRRSV antibody and that it can differentiate among PRRSV isolates.
对多种条件进行了评估和改进，以提高血清中和（SN）试验检测感染猪繁殖与呼吸综合征病毒（PRRSV）的猪体内抗体的灵敏度。通过在病毒稀释液中添加20%的新鲜猪血清以及使用源自MA-104细胞系的敏感细胞克隆（MARC-145）， consistently获得了更高的SN滴度。用于评估SN试验的检测血清取自2组经鼻感染PRRSV（MN-1b）的3周龄仔猪。使用改进方法，接种后（PI）9至11天首次检测到SN抗体，在PI 11至21天出现明显峰值。随后抗体下降，在PI 41至45天观察到第二个峰值。当使用20%加热猪血清或不添加补充猪血清进行试验时，未观察到第一个抗体峰值，SN抗体仅在PI 32至41天可检测到。发现PI 2至3周期间的SN抗体对2-巯基乙醇或抗猪IgM处理敏感。当试验中使用同源PRRSV分离株时，SN抗体滴度较高，但对异源PRRSV分离株则明显较低。通过间接荧光抗体试验检测同源和异源PRRSV分离株时，未观察到抗体滴度的差异。这些结果表明，改进的SN方法可用于更早、更高地检测PRRSV抗体，并且可以区分PRRSV分离株。
