Evaluation of Excretory-Secretory Products and Somatic Worm Antigens for the Serodiagnosis of ExperimentalParelaphostrongylus TenuisInfection in White-Tailed Deer

Abstract

Abstract. Three different antigen preparations of Parelaphostrongylus tenuis were assessed for their effectiveness in an indirect enzyme-linked immunosorbent assay (ELISA) to diagnose experimental infection of white-tailed deer (WTD). The antigen preparations were the excretory-secretory products of third-stage larvae (ES-L3), somatic antigens of third-stage larvae (sL3), and somatic antigens of the adult stage (sA) of P. tenuis. The relative sensitivities of the antigen preparations in indirect ELISA were ES-L3 Ͼ sL3 Ͼ sA. Immunoglobulin G (IgG) antibodies to ES-L3 and sL3 could be detected 14 days postinfection and were consistently present in all infected animals from the first month to the end of the experiment at 5 months. In contrast, IgG antibodies to sA could not be detected at any time in 2 infected WTD. ES-L3 and sL3 proved reliable in the early detection of anti-P. tenuis antibodies and in the serological monitoring of experimentally infected animals. Significant cross-reactivity between all P. tenuis antigen preparations and sera from animals infected with parasites other than P. tenuis may preclude their use for field diagnosis. Nevertheless, isolation of unique P. tenuis antigen(s) should lead to the development of a specific serological test for infected white-tailed deer.White-tailed deer (WTD; Odocoileus virginianus) are commonly infected with the meningeal worm Parelaphostrongylus tenuis (Nematoda: Protostrongylidae) in most of the eastern half of North America. Prevalence rates of more than 80% have been reported. 4,15,28 goats, and llamas can also acquire infections when their grazing areas overlap that of WTD, and the results may be fatal. 1,16,20,33 Many closely related protostrongylid parasites share geographical and host preferences with P. tenuis. Parelaphostrongylus andersoni is present across North America and infects WTD 25 and caribou, 18 Elaphostrongylus rangiferi commonly infects caribou in Newfoundland, Canada, 17 whereas Parelaphostrongylus odocoilei infects WTD and mule deer 25 in western North America. Elaphostrongylus cervi naturally infects red deer and has been shown experimentally to cause severe neurological disease in mule deer. 12 Elaphostrongylus cervi has a wide geographical distribution but is believed to be absent in North America. 12,13 Current diagnosis of P. tenuis infection in WTD relies on the demonstration of the first-stage larvae (L1) in the feces of infected animals by the Baermann technique. The problems with the technique and its limitations for clinical diagnosis are well documented. 11,31 In a recent study 28 L1 were detectable in less than twothirds of 311 necropsy-confirmed, P. tenuis-infected WTD because of the failure of infected animals to excrete larvae or the limitation of the Baermann technique or both. Furthermore, because L1 of P. tenuis are indistinguishable from the L1 of many other protostrongylids, P. tenuis infection can be definitively diagnosed only by the recovery and identification of the adult worm from the central nervous system (CN...

Detection of Anti-Parelaphostrongylus Tenuis Antibodies in Experimentally Infected and Free-Ranging Moose (Alces Alces)

“…For instance, antibodies could not be detected by the test at any time in three animals given three to 30 L3 and from which one to nine adult worms were recovered postmortem. The relative effectiveness of the two antigen preparations in detecting P. tenuis-infected moose is similar to observations reported for WTD in which antibodies against the somatic antigens of the adult worm were not detected in two of six deer inoculated with six and 20 worms (Ogunremi et al, 1999a). The relative sensitivity of antigen preparations in an indirect ELISA used for experimentally infected deer was ES-L3Ͼsomatic-L3Ͼsomatic adult antigen.…”

“…Excretory-secretory (ES) products of L3 and the somatic adult worm antigens of P. tenuis were prepared following published protocols (Ogunremi et al, 1999a(Ogunremi et al, , 2002 with some modifications. Briefly, batches of ES products were prepared by culturing about 2,500 L3 in RPMI containing 5% fetal calf serum (FCS), penicillin (100 U/ml), streptomycin (100 g/ml), and amphotericin B (1.25 g/ml) at 37 C with 5% CO 2 for about 28 hr.…”

“…Details of anti-P. tenuis ELISA using either ES products of L3 or somatic adult parasite antigens have been described previously (Ogunremi et al, 1999a(Ogunremi et al, , 2002. In this study, microtiter plates were coated with ES products diluted in PBS (1 in 3) or with 0.46 g of somatic adult antigens.…”

“…Even longer periods were required in animals given doses of 15 L3 (Bienek et al, 1998). Most of these problems were overcome by Ogunremi et al (1999aOgunremi et al ( , 2002 who used parasite excretory-secretory (ES) products as antigens to detect serum antibodies in WTD and elk. Anti-P. tenuis antibodies were detectable as early as 14 DPI in WTD, and between 14 and 28 DPI in elk.…”

“…In an effort to produce a more convenient and reliable diagnostic test for parelaphostrongylosis in moose, an enzymelinked immunosorbent assay (ELISA) was developed similar to the one previously used to detect P. tenuis in WTD (Ogunremi et al, 1999a) but incorporating a moose specific antibody conjugate. In this study, preliminary assessment of test sensitivity and specificity was performed using sera from experimentally infected moose whose infection levels were confirmed by necropsy.…”