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[Effect of hypodermyiasis in cattle on milk-production indicators in 1st-calvers].

We investigated the effect of hypodermosis on the quantitative and some qualitative indicators of milk from 20 experimental and 18 control first-calvers of the Pinzgau cattle breed. The experiment took place at two experimental localities in mountainous pastures of the Central-Slovakian region. In the experimental animals, treated with Hypocid, the production of milk per dairy cow increased on an average by 115.98 kg, i.e. 24.83%, over the experimental period of 61 days (May, June) with an average invasion intensity of 5.94 larvas in control animals. Milk fat production increased on an average by 7.20 kg, i.e. 34.97%. Production recalculated to FCM milk amounted on an average to 31.61%. The profitability of treating hypodermosis with the Hypocid preparation is expressed by the average savings of 0.40 Kcs per litre of milk per day.

Animals

[Therapy of hypodermyiasis in heifers from the economic point of view].

The test set of animals consisted of sixty one- to two-year-old heifers of the Slovak Spotted and Pinzgau breeds kept at three sites. The Hypocid preparation (containing 40% trichlorphon) in the dose of 15 ml per 100 kg of live weight was applied to these cows by the lavage method in the sacrolumbar region of the spine in 1973. Another group, consisting of 58 heifers, was left untreated as controls. In the experimental period extending over 158, 150 and 120 days at different sites (143 days on an average), weight gains and the health condition of the experimental and control animals were checked in monthly intervals. The average extensity of invasion in the control heifers was 79.31% and the intensity of invasion was 14.58%. The extenseffectiveness of Hypocid (EE) was 97.90% and the intenseffectiveness of the preparation (IE) was 99.99%. The results prove a negative effect of hypodermatosis on the weight gains of untreated heifers and high profitability of the therapy: after subtraction of the costs of therapy the savings were 1.74, 3.88 and 2.25 crowns per kg gain per day (2.62 crowns on an average). The veterinary measures gave the following savings per each crown expended: 2,243.55; 3,066.85 and 922.83 crowns (depending on site).

Animals

Shared epitopes between the soluble proteins of Hypoderma lineatum and Hypoderma bovis first instars.

Cattle are known to acquire immunological resistance to hypodermyiasis by repeated exposure to both species of cattle grubs, Hypoderma lineatum (Villers) and Hypoderma bovis (L.). Vaccination of cattle with purified proteins of H. lineatum, particularly hypodermin A, is known to protect cattle against hypodermyiasis by this species. The development of a protective recombinant vaccine against both species using hypodermin A isolated from H. lineatum would require that immunological epitopes be shared by complementary proteins in H. bovis. The purpose of this study was to investigate the soluble proteins of H. bovis first-instars for shared epitopes with H. lineatum. Soluble H. lineatum and H. bovis first-instar larval proteins were resolved by nondenaturing polyacrylamide electrophoresis, blotted onto nitrocellulose paper, and probed with selected polyclonal cow, polyclonal rabbit, and mouse monoclonal antisera. Considerable cross-reactivity was demonstrated by antibodies in the serum of an H. lineatum-infested cow as 6 of 10 resolved H. bovis proteins were bound by the antibodies. The most common shared epitope(s) was associated with hypodermin C, a collagenolytic protease. Hypodermin A shared epitope(s) were noted on 1 prominent H. bovis band (HB1-2). Hypodermin B, a prominent protein in H. lineatum, did not appear to share epitopes with H. bovis proteins. Shared epitopes between H. bovis proteins and hypodermins A and C of H. lineatum would suggest that cross-protection of cattle against H. bovis can be expected by vaccination with recombinant proteins of H. lineatum.

Animals

[The larval development of the warble-fly Oestromyia leporina Pall. (Deptera, Hyodermah'dae) (author's transl)].

The present paper deals with the larval development of the warble-fly Oestromyia leporina and especially with the development of the first instar larvae (L 1). The hatching from the egg and the modus of infection is described. The migration of the L 1 within the host is reported for the first time as well as the perforation of the skin after the migration period. Exact dates on the duration of the different larval stages are given. Experimental infection reveals a partial immunization of the host against new infections. Some remaining problems of larval biology are discussed. By comparison several facts suggest our present knowledge of the perforation of larval (L 1) Hypoderma bovis probably to be wrong.

Animals

[Cultivation of the warble-fly Oestromyia leporina pall. (Diptera, Hypodermatidae) and its biological prerequisites (author's transl)].

The warble-fly Oestromyia leporina was cultivated for four generations in the laboratory. In the present paper the technic of laboratory mating and the modus of experimental infection of the host are described. The fertility of females is tested by experiments and by dissections. It is shown how the diapause of the puparia can be shortened and how it can be omitted. The successful infection of several species of small mammals demonstrates that O. leporina can be colonized not only on the natural host but also on some common laboratory animals like mice and rats.

Animals

[Histological reactions of the host induced by the larvae of the warble-fly Oestromyia leporina Pall. (Diptera, Hypodermatidae) (author's transl)].

The histological reactions of Mastomys natalensis induced by the larvae of Oestromyia leporina are described from the start of the infection to the complete healing of the evacuated cyst. Against the migrating larva no cellular reactions take place. After the larva settles, the most obvious feature is a non-suppurative inflammation of the surrounding tissue, while a layer of granulation tissue, infiltrated with eosinophils, is built up around the parasite. About 13 days p.i. the number of eosinophils starts to decrease again. No giant cells are present; plasmocytes and lymphocytes are relatively scarce. A few days before the parasite leaves the host, the inner surface of the warble is infiltrated with masses of neutrophils, obviously caused by secondary invasion of bacteria through the warble opening. After the parasite leaves the host, the repair of the tissue takes place within three weeks. The remaining scar tissue contains cells carrying haemosiderin, which disappears entirely about two months later.

Animals

The response of cattle vaccinated with hypodermin A to a natural infestation of Hypoderma bovis and Hypoderma lineatum.

In this study, we have determined whether immunization with hypodermin A (HA), associated with various adjuvants, could provide protective immunity for calves when challenged with a natural hypoderma infestation. Groups of naive calves were vaccinated with HA antigen alone or with adjuvants [Freund's incomplete adjuvant (FIA) or alumina phosphate (AP)]. Subcutaneous injection with HA antigen with or without adjuvant did not significantly protect calves against a natural hypodermosis infestation. The humoral response during the infestation period was evaluated by ELISA. A significant earlier and greater response was induced in groups vaccinated with HA alone and HA combined with FIA. These results indicate that HA, in this vaccination protocol, induces a very incomplete protection in calves exposed to a natural infestation.

Adjuvants, Immunologic

Effect of hypodermin A, an enzyme secreted by Hypoderma lineatum (Insect Oestridae), on the bovine immune system.

The absence of any inflammatory reaction around the first instar larvae (L1) of Hypoderma sp. in previously uninfested cattle suggested that these larvae may escape the non-specific defence system of the host. Immunosuppression had been noted during an experimental infestation. The aim of this work was to determine more precisely the potential role of hypodermin A (HA), an enzyme secreted by the larvae, in this immunosuppression. HA was found to have no effect on unstimulated lymphocytes from naive cattle but could influence the response of these cells to mitogens. In calves, injection of HA was accompanied by a decrease in the lymphocyte proliferative response to mitogens. This immunodepression lasted only for the duration of enzyme injections. In cattle, when HA is added, the antigen-dependent proliferative response increased significantly after 1 week of injection and disappeared 2 weeks after the end of the injection period. Finally, the rate of production of anti-HA antibodies increased at the same rate for calves and cows, and achieved a similar level. These results suggest that HA significantly modified the lymphoproliferative response for naive cattle and, to a lesser extent, immune cattle during the time of administration only.

Animals

Effect of ivermectin treatment on anti-hypodermin C titers of Asturiana cattle naturally infected with Hypoderma lineatum.

The collagenase (hypodermin C) from soluble crude extracts of Hypoderma lineatum 1st-instar larvae was purified by reverse-phase HPLC and used in a new indirect ELISA test. This pure protein had several advantages over the use of crude larval extracts allowing a much better discrimination between infested and non-infested cattle. The anti-hypodermin C titers of 19 Asturiana cattle were estimated over the course of a natural H. lineatum infestation cycle, in which the effect of ivermectin treatment was also investigated. The results showed differences in the onset and ending of the infestation with respect to those described for other European countries. The ivermectin treatment proved to be very effective and treated animals had relatively low anticollagenase titers.

Animals

Use of pooled serum or milk samples for the epidemiological surveillance of bovine hypodermosis.

An enzyme-linked immunosorbent assay (ELISA) was used on pooled serum and milk samples to determine whether hypodermosis could be detected where a larger sero-epidemiological survey was required. This study was undertaken to assess the potential of this assay for testing sera on milk samples, pooled from 10 cows, and determining the period of the year when detection was optimal. The sensitivity of the assay was determined by increasingly diluting a positive serum with pooled negative sera, from 1:10 to 1:100. The diagnostic lower limit of the assay requires at least two serological reactors within a herd of 100. The kinetic development and depletion of anti-Hypoderma antibody of individual and pooled sera or milk from 30 cows was evaluated from November to July. Anti-Hypoderma antibody levels of two groups of 8 calves, one control and one teated with ivermectin (Ivomec), were tested from October to June. These preliminary results indicate that an ELISA assay on serum or milk samples pooled from 10 cows can be used between February and April to evaluate the prevalence of hypodermosis within cattle herds in France, demonstrating the feasibility of using pooled serum already collected for bovine leucosis testing.

Animals

Antigen-specific lymphocyte proliferative responses in vaccinated and Hypoderma lineatum-infested calves.

Cattle infested with the common cattle grub, Hypoderma lineatum (Villers) develop specific humoral antibodies and a cellular immune reaction, defined by delayed-type hypersensitivity, to purified H. lineatum proteins. This investigation was designed to study the antigen-specific bovine lymphocyte response to hypodermin A (HyA), a serine protease of larval first-instar H. lineatum. Calves were vaccinated with either native or denatured HyA, and challenge-infested with H. lineatum. The kinetic development of a cellular immune response to HyA was monitored during vaccination and infestation. The HyA-specific responses were highly variable and weak during vaccination and infestation. Although HyA-specific lymphocyte blastogenic responses were observed, no correlation was noted between the magnitude of antigen-specific, peripheral lymphocyte proliferation and larval mortality. In striking contrast to responses observed during infestation, intense HyA-specific lymphocyte responses were observed with 3 calves 6 months after recovery from infestation. In addition, those responses were further heightened by a 250 micrograms booster injection of pure HyA.

Animals

Enhanced resistance to cattle grub infestation (Hypoderma lineatum de Vill.) in calves immunized with purified hypodermin A, B and C plus monophosphoryl lipid A (MPL).

The influence of an antigen-specific cellular and humoral immune response, stimulated by immunization, on survival of a challenge infestation of Hypoderma lineatum was investigated. Calves immunized with a purified combination of hypodermin A, B and C plus monophosphoryl lipid A (MPL) developed a strong antigen-specific cellular immune response by completion of the immunization schedule which persisted to 12 weeks post-infestation. Responsiveness of peripheral blood lymphocytes to the mitogens concanavalin A and pokeweed was also elevated at 4 and 12 weeks post-infestation. Western blot analysis at the time of maximum grub counts demonstrated that immunized calves responded to hypodermin A, B and C while those receiving only MPL or infested controls responded only to hypodermin B and C. The antigen-specific antibody response as measured by ELISA at maximum grub count was significantly higher in vaccinated calves than in infested controls while the response in calves receiving only immunostimulator was also significantly elevated. Immunized (antigen plus MPL) calves produced 5.0 +/- 6.9 grubs per animal which successfully pupated while those receiving MPL alone produced 16.4 +/- 6.1 and infested controls produced 32.2 +/- 10.9 grubs per animal.

Animals

Moxidectin: systemic activity against common cattle grubs (Hypoderma lineatum) (Diptera: Oestridae) and trichostrongyle nematodes in cattle.

Moxidectin, a systemic insecticide, was evaluated for its efficacy against the migrating first instars of the common cattle grub, Hypoderma lineatum, and against nematode egg production in beef cattle. It was observed that all three levels (0.1, 0.2 and 0.4 mg moxidectin kg-1) were 100% effective against cattle grubs when administered as a s.c. injection. The same levels of treatment were very effective (90-100%) in reducing trichostrongyle nematode egg production. However, there was a slight indication that at least one species, Cooperia oncophora, was not completely eliminated, as it was observed that small numbers of eggs began to appear after 2 weeks post-treatment when there had been no opportunity for reinfection.

Animals

Oral and parenteral administration of ivermectin to reindeer.

The anti-parasitic effect of the orally administered paste formulation of ivermectin (Ivomec) in reindeer was evaluated by means of a trial designed to compare the efficacies of orally and s.c. administered ivermectin at the same dosage (0.2 mg kg-1 body weight) in naturally infected adult reindeer (n = 92). Both formulations were 100% effective against larvae of the warble fly, Oedemagena tarandi, while oral treatment was less efficacious than s.c. injection against parasitic nematodes. Both formulations, but particularly the injectable ivermectin treatment, increased the weight gain of pregnant females compared to that of those not treated.

Administration, Oral