Rosypal A C, Troy G C, Duncan R B, Zajac A M, Lindsay D S
Department of Biomedical Sciences and Pathobiology, Virginia Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24061, USA.
J Vet Intern Med. 2005 Nov-Dec;19(6):802-9. doi: 10.1892/0891-6640(2005)19[802:uodtui]2.0.co;2.
Eight female beagles were infected with 1 x 10(7) (low dose, LD) or 2 x 10(8) (high dose, HD) promastigotes of a North American isolate of Leishmania infantum infantum (LIVT-1 strain) isolated from naturally infected Virginia Foxhounds. Two female beagles served as negative controls and 2 male beagles chronically infected (> 3 years) with Leishmania infantum chagasi were positive controls. Bone marrow (BM) and lymph node (LN) aspirates were collected every 6-8 weeks for cytologic evaluation, parasite culture, and polymerase chain reaction (PCR). Serum samples were collected monthly for determination of serologic responses by indirect fluorescent antibody test (IFAT) and diagnostic rK39 antigen. Cultures of BM and LN aspirates and cytology evaluation were consistently positive in positive control dogs during the course of study. Negative control dogs were negative on BM and LN cultures and on cytologic evaluation of aspirates. Amastigotes were present on cytological examination of BM aspirates in 2 experimentally infected dogs. Cultures of LN aspirates were positive on 22 samples, whereas BM cultures were positive on 12 samples for all dogs. IFA titers ranged from 0 to 1 :400 in experimentally infected dogs during the course of the study. Recombinant K39 immunoassay tests were consistently positive in positive control dogs and in the HD dogs by approximately 8 weeks after infection. BM PCR products were identified more consistently in the HD dogs compared with the LD dogs. Kappa statistics indicated PCR correlated better with cultures and cytology than did IFAT or the rK39 immunoassay results in the experimentally infected dogs.
八只雌性比格犬感染了从自然感染的弗吉尼亚猎狐犬中分离出的北美婴儿利什曼原虫婴儿分离株（LIVT-1株）的1×10⁷（低剂量，LD）或2×10⁸（高剂量，HD）前鞭毛体。两只雌性比格犬作为阴性对照，两只慢性感染（超过3年）恰加斯利什曼原虫的雄性比格犬作为阳性对照。每6 - 8周采集骨髓（BM）和淋巴结（LN）抽吸物用于细胞学评估、寄生虫培养和聚合酶链反应（PCR）。每月采集血清样本，通过间接荧光抗体试验（IFAT）和诊断性rK39抗原测定血清学反应。在研究过程中，阳性对照犬的BM和LN抽吸物培养及细胞学评估始终呈阳性。阴性对照犬的BM和LN培养以及抽吸物的细胞学评估均为阴性。在2只实验感染犬的BM抽吸物细胞学检查中发现了无鞭毛体。所有犬的LN抽吸物培养有22份样本呈阳性，而BM培养有12份样本呈阳性。在研究过程中，实验感染犬的IFA滴度范围为0至1:400。重组K₃₉免疫测定试验在阳性对照犬和HD犬中，感染后约8周一直呈阳性。与LD犬相比，HD犬中BM PCR产物的鉴定更一致。卡方统计表明，在实验感染犬中，PCR与培养和细胞学的相关性比IFAT或rK39免疫测定结果更好。
