Murray M J, Eichorn E S, Dubovi E J, Ley W B, Cavey D M
Marion duPont Scott Equine Medical Center, Virginia-Maryland Regional College of Veterinary Medicine, Leesburg 22075, USA.
Equine Vet J. 1996 Nov;28(6):432-6. doi: 10.1111/j.2042-3306.1996.tb01614.x.
Whole blood and serum were collected from foals to determine the prevalence of Equine herpesvirus type 2 (EHV 2) infection in foals, age at which infection can first be identified and serological responses to infection. Equine herpesvirus type 2 was isolated from peripheral blood mononuclear cells (PBMC) from 68 of 69 foals, 1-8-months-old, sampled once. Virus isolation was performed twice at intervals of 2-7 months on PBMCs from 33 foals and EHV2 was isolated on both occasions in all but one foal (negative, then positive). Regression analysis of log2-transformed reciprocal serum EHV2 virus neutralising (VN) titres revealed that in foals age 1-7 months, EHV2 VN antibody titre was positively correlated with age (r = 0.94). Paired serum samples were obtained from 58 foals, with the first samples collected age 1-6 months and the second samples collected 2-4 months later. There were significant (P < 0.05) increases in mean VN titres to EHV2 in foals sampled initially at age 1-4. Eight foals had blood sampled prior to sucking and at age 7, 20, 30 and 45 days. Each foal was negative for EHV2 in PBMC and each foal had a negative serum EHV2 VN titre immediately after birth. Each foal was positive for EHV2 in PBMC by age 45 days, with the earliest isolation at 25 days. Tracheal aspirate fluid and peripheral blood were collected from 20 foals without clinical signs of respiratory disease and from 30 foals with clinical signs of lower respiratory disease. In 20 foals without clinical signs of respiratory disease, EHV2 was isolated from tracheal aspirates (1/20 foals) and PBMC (20/20 foals) and in 30 foals with such clinical signs, from trachea aspirates (20/30 foals: P < 0.01) and from PBMC (30/30 foals). In one 6-month-old foal, EHV1, but not EHV2, was isolated from the tracheal aspirate, 3 months after EHV2 had been isolated from a tracheal aspirate. These results demonstrate a greater prevalence of EHV2 in lower respiratory secretions in foals with clinically apparent lower respiratory disease, but a cause and effect relationship between the virus and lower respiratory disease remains to be elucidated. It is noteworthy, however, that of virus isolations performed on 50 tracheal aspirates, a virus (EHV1) other than EHV2 was isolated only once.
采集马驹的全血和血清，以确定2型马疱疹病毒（EHV 2）在马驹中的感染率、首次可识别感染的年龄以及对感染的血清学反应。从69匹1至8月龄的马驹中采集外周血单个核细胞（PBMC），其中68匹分离出了2型马疱疹病毒，所有马驹均只采样一次。对33匹马驹的PBMC每隔2至7个月进行两次病毒分离，除一匹马驹（先阴性，后阳性）外，其他马驹在两次检测中均分离出了EHV2。对经log2转换的血清EHV2病毒中和（VN）滴度进行回归分析发现，1至7月龄的马驹中，EHV2 VN抗体滴度与年龄呈正相关（r = 0.94）。从58匹马驹中获取配对血清样本，第一份样本在1至6月龄时采集，第二份样本在2至4个月后采集。最初在1至4月龄采样的马驹中，其EHV2的平均VN滴度有显著（P < 0.05）升高。8匹马驹在吮乳前以及7、20、30和45日龄时采血。每匹马驹出生后PBMC中的EHV2均为阴性，血清EHV2 VN滴度也均为阴性。到45日龄时，每匹马驹PBMC中的EHV2均为阳性，最早在25日龄时分离出病毒。从20匹无呼吸道疾病临床症状的马驹和30匹有下呼吸道疾病临床症状的马驹中采集气管吸出液和外周血。在20匹无呼吸道疾病临床症状的马驹中，从气管吸出液中分离出EHV2的有1匹（1/20），从PBMC中分离出EHV2的有20匹（20/20）；在30匹有此类临床症状的马驹中，从气管吸出液中分离出EHV2的有20匹（20/30：P < 0.01），从PBMC中分离出EHV2的有30匹（30/30）。在一匹6月龄的马驹中，在从气管吸出液中分离出EHV2 3个月后，从气管吸出液中分离出了EHV1，而非EHV2。这些结果表明，在有明显下呼吸道疾病的马驹中，EHV2在下呼吸道分泌物中的感染率更高，但病毒与下呼吸道疾病之间的因果关系仍有待阐明。然而，值得注意的是，在对50份气管吸出液进行病毒分离时，除EHV2外，仅一次分离出了另一种病毒（EHV1）。
