Serological and Immunological Responses of Calves to Infection with Trichostrongylus axei
1963; American Society of Parasitologists; Volume: 49; Issue: 4 Linguagem: Inglês
10.2307/3275771
ISSN1937-2345
Autores Tópico(s)Coccidia and coccidiosis research
ResumoInoculation of calves with single and multiple doses of infective larvae, a mixture of all parasitic stages of development, and adult Trichostrongylus axei alone, resulted in the production of circulating antibodies as detected by the passive hemagglutination test. The infections also resulted in increases in the relative quantities of gamma globulin. On the basis of numbers of worms present at necropsy, worm size, percentage of inhibited development, and absence of precipitins against infective larvae, there was no evidence of a protective function associated with the hemagglutinins and the elevated levels of gamma globulin. There was some indication of an inverse relationship between the level of circulating antibody and fecal egg count. Although there is a rather extensive bibliography on the subject of circulating antibody in sheep infected with gastrointestinal nematodes, the serological response of cattle to nematode infections has received little attention. Roberts (1957) and Ross and Armour (1960) detected complement-fixing antibodies in grazing calves harboring mixed nematode infections; however, the former investigator rarely found titers, and then only at very low levels, in calves with experimental infections of Haemonchus placei. Roberts, Elek, and Keith (1962) were able to detect hemagglutinins and complementfixing antibodies in calves infected with Oesophagostomum radiatum, but again the titers were generally very low. This report presents data obtained from pure experimental infections of calves with the stomachworm, Trichostrongylus axei. This study had three primary objectives, namely, to determine whether infection of calves with T. axei would stimulate the production of circulating antibody, whether infection established with adult worms would evoke an antibody response, and whether there would be any correlation between circulating antibody and immunity to reinfection. Some of the results Received for publication 7 February 1963. * Present address: National Animal Disease Laboratory, Animal Disease and Parasite Research Division, Agricultural Research Service, U. S. Department of Agriculture, Ames, Iowa. of this study have been reported in abstract form (Herlich and Merkal, 1959). MATERIALS AND METHODS All calves were grade Jerseys raised free of helminth parasites other than Strongyloides papillosus. The calves were kept in individual concretefloored pens that were cleaned daily. Rations consisted of alfalfa hay and grain; water and salt were available ad lib. Four calves were inoculated orally as follows: no. 1, with a transfer of another calf's abomasal contents containing 25,000 adult T. axei; no. 2, with a transfer of abomasal contents containing a like number of worms, but comprising all stages from parasitic third-stage to sexually mature worms; no. 3, with a single dose of 25,000 infective larvae; and no. 4, with 25,000 infective larvae divided into 20 doses delivered over a 4-week period. A fifth calf was left uninfected as a control. The transfers of abomasal contents were effected as follows: 200,000 infective larvae were given to each of two calves, one 50 days and the second 23 days before initiation of the experiment. Both were killed on the same day. Their stomachs were removed, opened, and washed gently in warm physiological saline. The number of worms in the contents from each calf was determined by counting all the worms in a 2% sample. As more worms were found in the calf inoculated 23 days before slaughter, the total volume of its abomasal contents was reduced to provide the same number of worms recovered from the calf that had been inoculated 50 days before slaughter. The abomasal contents were then allowed to settle, the supernatant was discarded, and the sediment containing the worms was force-fed through nippled bottles to two helminth-free calves. The transfer procedure was facilitated by withholding feed from 623 This content downloaded from 157.55.39.153 on Mon, 19 Sep 2016 04:49:34 UTC All use subject to http://about.jstor.org/terms THE JOURNAL OF PARASITOLOGY TABLE I. Preand postchallenge maximum antibody titers in calves experimentally infected with Trichostrongylus axei, and numbers of worms recovered at necropsy. Maximum titer Calf From initial From Number worms inoculation challenge recovered at to challenge to necropsy necropsy No. Age (mo) Type of inoculation (12 weeks) (7 weeks) Trial 1 1504 20 Adult worms only 1 40 1 80 8,100 (1.9)1 1493 23 All parasitic stages I 40 1 320 7,450 (2.5) 1492 23 Single dose infective larvae I 320 1 5,120 21,135 (2.8) 1495 22 Twenty doses infective larvae 1 2,560 1 640 38,700 (2.0) 1512 18 Control 1 10 1: 320 11,490 (1.0) Trial 2 1555 26 Adult worms only 1: 40 1 80 8,650 (3.9) 1556 26 All parasitic stages I 10 1 40 8,150 (2.4) 1560 25 Single dose infective larvae I 160 1 5,120 29,250 (2.0) 1557 26 Twenty doses infective larvae 1 640 1 5,120 26,050 (3.0) 1561 24 Control 1 10 1 1,280 10,000 (1.0) 1Figures in parentheses represent percentages of worms that were immature. the donor calves and water and feed from the recipient calves for 24 hr prior to slaughter. Twelve weeks later, all calves, including the uninfected control, were challenged with 34,000 infective larvae, and 49 days after the challenge all calves were killed. This experimental procedure was replicated once, the only difference being that 28,000 worms were used in the initial infecting doses, and 32,000 larvae for the challenge. Fecal samples were collected thrice weekly, and nematode egg counts were made by the DCF technique using a solution of zinc sulfate as a flotation medium. Beginning just prior to inoculation of the calves, blood was collected weekly from the jugular vein and allowed to clot overnight in a refrigerator. Serum was then removed and placed in vials for storage at -20 C. Freshly recovered serum from each calf was checked each week for larval precipitins by the technique of Hawkins and Cole (1945). All calves were necropsied by the methods of Porter (1942) and Herlich (1956). Total number of worms recovered from each calf was determined by a dilution count based on an average of three 1/30 aliquots. Some worms recovered from each of the calves used in the first trial were killed in hot 70% alcohol, and the mean length of 25 worms of each sex from each calf was determined. When each trial was completed, all sera were tested for circulating antibodies by means of the passive hemagglutination test (Boyden, 1951) as modified by Soulsby (1956). Due to the rather large quantities of antigen needed, and as large numbers of adult H. contortus of sheep origin were available, this species served as the source of antigen prepared by the methods described by Soulsby (1956). It appeared that using antigen from this source would have no significant effect on the test as Soulsby had reported marked cross reactions and close relationships between antigens prepared from mixtures of stomach worms, mixtures of intestinal worms and single species of intestinal worms. Sera from all animals in the second trial were analyzed electrophoretically according to Beckman's procedure B, i.e., the paper strips impregnated with sera were kept in a Durrum' cell for 16 hr using a veronal buffer (pH 8.6) and an electric potential of 75 volts. The paper strips (30.5 cm long) were then stained with bromphenol blue and the serum protein patterns were evaluated with an Analytrol Integrating Densitometer.1
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