Paweska J T
Department of Virology, Onderstepoort Veterinary Institute, South Africa.
Onderstepoort J Vet Res. 1997 Jun;64(2):147-52.
Clinical, virological and serological responses were investigated in five pregnant donkey mares after experimental exposure to the South African asinine-94 strain of equine arteritis virus (EAV), and the duration of maternal immunity to EAV was studied in their foals. In four intranasally inoculated mares, fever with maximum rectal temperatures of 39.1-40.7 degrees C was recorded 2-11 d after challenge. All the inoculated mares developed mild depression, and a serous ocular and nasal discharge; in three mares mild conjuctivitis was observed. The virus was recovered from the nasopharynx and from buffy-coat samples of all the mares 3-10 d, and 2-18 d post inoculation (p.i.), respectively. Seroconversion to EAV was detected on days 8-10 p.i. Peak serum-virus-neutralizing antibody titres of log10 1.8-2.4, and IgG ELISA OD values of 0.85-2.15 were recorded 2-3 weeks p.i. The in-contact (p.c.) control mare developed fever on days 15-19 post exposure, and showed mild clinical signs of equine viral arteritis similar to those observed in the inoculated mares. Seroconversion to EAV was detected in the p.c. mare on day 20 post exposure, and virus was isolated from nasal swabs and blood samples collected at the time of the febrile response and 1-3 d afterwards. None of the mares aborted. After they had given normal birth 45-128 d p.i. or after p.c. exposure, no virus could be isolated from their placentas. The concentration of EAV-neutralizing antibody in colostrum was two to eight times higher than in serum samples collected at the time of parturition. All the foals born to infected mares were clinically normal at the time of birth and throughout the subsequent 1-2 months of observation. No EAV was recovered from the buffy-coat fraction of blood samples collected at birth nor from those collected on days 1, 2 and 7 after birth. Also, no virus-serum-neutralizing or IgG ELISA antibody to EAV was detected in sera collected immediately after birth before the foals started nursing. The colostrum-derived maternal antibodies against EAV gradually declined and could not be detected by either the VN test or ELISA for 2-3 months after birth. This study demonstrates that the asinine-94 strain of EAV does not cause abortion in pregnant donkey mares. Furthermore, no carrier state could be demonstrated in foals born to mares infected at the time of pregnancy.
对五匹怀孕母驴在实验性接触南非马动脉炎病毒（EAV）的94株驴毒株后，进行了临床、病毒学和血清学反应的研究，并对其驹的母源EAV免疫力持续时间进行了研究。在四匹经鼻接种的母驴中，攻毒后2 - 11天记录到发热，直肠最高温度为39.1 - 40.7摄氏度。所有接种的母驴都出现轻度抑郁，并有浆液性眼鼻分泌物；在三匹母驴中观察到轻度结膜炎。分别在接种后3 - 10天和2 - 18天，从所有母驴的鼻咽部和血沉棕黄层样本中分离到病毒。接种后第8 - 10天检测到EAV血清转化。接种后2 - 3周记录到血清病毒中和抗体峰值滴度为log10 1.8 - 2.4，IgG ELISA OD值为0.85 - 2.15。接触（p.c.）对照母驴在接触后第15 - 19天发热，并表现出与接种母驴相似的轻度马病毒性动脉炎临床症状。接触对照母驴在接触后第20天检测到EAV血清转化，并且在发热反应时及之后1 - 3天采集的鼻拭子和血样中分离到病毒。没有母驴流产。在接种后45 - 128天或接触后正常分娩后，从它们的胎盘中未分离到病毒。初乳中EAV中和抗体的浓度比分娩时采集的血清样本高两到八倍。所有感染母驴所生的驹在出生时及随后1 - 2个月的观察期内临床均正常。出生时采集的血样血沉棕黄层部分以及出生后第1、2和7天采集的血样中均未分离到EAV。此外，在驹开始哺乳前出生后立即采集的血清中未检测到针对EAV的病毒血清中和抗体或IgG ELISA抗体。初乳来源针对EAV的母源抗体逐渐下降，出生后2 - 3个月通过VN试验或ELISA均检测不到。本研究表明，EAV的94株驴毒株不会导致怀孕母驴流产。此外，怀孕时感染的母驴所生的驹中未发现带毒状态。
