‘Plantibodies’: a flexible approach to design resistance against pathogens

Engineering resistance against various diseases and pests is hampered by the lack of suitable genes. To overcome this problem we started a research program aimed at obtaining resistance by transfecting plants with genes encoding monoclonal antibodies against pathogen specific proteins. The idea is that monoclonal antibodies will inhibit the biological activity of molecules that are essential for the pathogenesis. Potato cyst nematodes are chosen as a model and it is thought that monoclonal antibodies are able to block the function of the saliva proteins of this parasite. These proteins are, among others, responsible for the induction of multinucleate transfer cells upon which the nematode feeds. It is well documented that the ability of antibodies to bind molecules is sufficient to inactivate the function of an antigen and in view of the potential of animals to synthesize antibodies to almost any molecular structure, this strategy should be feasible for a wide range of diseases and pests.Antibodies have several desirable features with regard to protein engineering. The antibody (IgG) is a Y-shaped molecule, in which the domains forming the tips of the arms bind to antigen and those forming the stem are responsible for triggering effector functions (Fc fragments) that eliminate the antigen from the animal. Domains carrying the antigen-binding loops (Fv and Fab fragments) can be used separately from the Fc fragments without loss of affinity. The antigen-binding domains can also be endowed with new properties by fusing them to toxins or enzymes. Antibody engineering is also facilitated by the Polymerase Chain Reaction (PCR). A systematic comparison of the nucleotide sequence of more than 100 antibodies revealed that not only the 3′-ends, but also the 5′-ends of the antibody genes are relatively conserved. We were able to design a small set of primers with restriction sites for forced cloning, which allowed the amplification of genes encoding antibodies specific for the saliva proteins ofGlobodera rostochiensis. Complete heavy and light chain genes as well as single chain Fv fragments (scFv), in which the variable parts of the light (V_L) and heavy chain (V_H) are linked by a peptide, will be transferred to potato plants. A major challenge will be to establish a correct expression of the antibody genes with regard to three dimensional folding, assembly and intracellular location.     

Effect of fertilizers on Taenia saginata Goeze, 1782 egg viability in vitro

The effect of seven fertilizers on the viability of Taenia saginata eggs was tested in vitro. The most destructive effect was produced by lime-nitrogen, in which the eggs survived only for 24 hours in the substance and for two days in a saturated solution. In the limestone the eggs survived for three days.     

Arbovirus isolations from mosquitoes in South Slovakia.

In the years 1973 and 1975 mosquitoes and some other Diptera (Tabanidae, Simuliidae, Hippoboscidae) were tested for virus. 13,924 mosquitoes, 75 horseflies and 60 blackflies were processed in 1973. Five strains of Tahyna virus were isolated from mosquito species Aedes vexans. 3,378 mosquitoes and 12 sheep keds were tested for virus in 1975. Twelve strains of Calovo virus were isolated from Anopheles maculipennis and one strain of Tahyna virus was obtained from Aedes vexans mosquitoes.     

Scanning electron microscopy of Setaria labiatopapillosa (Alessandrini, 1848) from cattle of Kazakhstan.

Surface structures of males and females of Setaria labiatopapillosa were studied by means of scanning electron microscopy at high magnification. It was found that the surface of buccal cavity, lateral appendages, vulva, anus and cloaca differs from the remaining cuticle. The shape of internal and external mouth papillae, amphids, deirids, postdeirid and phasmidial pore was studied. On the surface of the postdeirid are four small papillae arranged in a typical manner around the depression from which projects a needle-like formation. The ventral bands are formed by fine longitudinal parallel folds of the cuticle. Some anomalies in the localization of postcloacal papillae were observed.     

First record of bacillary rickettsia-like organisms in European tick Dermacentor marginatus (Sulzer).

Bacillary rickettsia-like organisms (BRLO) were found in the tick Dermacentor marginatus. They are gram-negative and differ from common bacteria and reckettsiae both in the cultivation conditions and morphology. BRLO are non-pathogenic for ticks and guinea pigs. In our studies they were isolated on half-engorged females of D. marginatus, on which they are still maintained.     

Studies on viremia and antibody formation in ducklings and goslings after experimental infection with Lednice (Yaba 1) virus.

A very low virus level was found for a short time in the blood of ducklings and goslings after experimental Lednice (Yaba 1) virus infection by subcutaneous (scut) and intranasal (inas) route and in blood of ducklings also after infection by intracerebral (icer) route. Subsequently virus neutralizing antibody formation was examined. Antibody formation was found in most of animals. In goslings onset of antibody formation seems to be slower than in ducklings after the same virus infection dose; vice versa, in ducklings antibody titer decreased after 6 weeks. Using low infection virus dose, neutralizing antibody level in ducklings was lower than in the former case. On examining the blood and the organs, the virus was detected in a very low amount and for a very short time in blood and spleen of goslings and only in blood of ducklings.     

Histological studies on cow intestinal mucosa and electron microscopic studies of the ruminal epithelium of cows fed a deficient diet for a prolonged time]

Histological and histochemical studies were carried out on the gastro-intestinal mucosa of three experimental cows (roughages/maize silage) and three control animals. The animals were slaughtered on termination of the long-term trial. Mucosa samples were taken, for further study, from the rumen, the duodenum, the jejunum, the large intestine and the appendix. Histochemical analysis did not reveal any essential differences in the activities of non-specific esterase, alkaline and acid phosphatase and lactic acid dehydrogenase in the mucosa of the rumen, the large and the small intestine and the appendix of both the experimental animals and the controls. The experimental animals were found to exhibit a higher rate of glutamate-dehydrogenase activity in the ruminal mucosa and in the mucosa of the large and small intestine. A higher succinate dehydrogenase activity was observed in the ruminal mucosa of the experimental animals, relative to that of the controls, while the activity in the intestinal mucosa was decreased. Only slight changes were noted in the activity of the enzymatic systems tested. Electron microscopic studies did not reveal any differences in the ultrastructure of the epithelial cells of the ruminal mucosa in both the experimental animal and the controls.     

Testing of the protective effect of cell-free lyophilized vaccine against Marek's disease in field trials]

The protective effect of a lyophilized vaccine against Marek's disease ("Keramvac"--Pfizer), prepared from a cell-free turkey's herpesvirus (strain FC 126), was compared in field trials with losses in the group of non-vaccinated chickens. Under the indicated conditions, the vaccine had only a 50.86% effectiveness. The possible causes of the reduced vaccination effect are discussed with regard to the pathomorphological and virological findings suggesting, among others, an increased incidence of the symptoms of the classical form of Marek's disease in the population investigated.     

Phage typing of strains of Staphylococcus aureus from staphylococcal mastitis of dairy cows]

Of 62 strains of Staphylococcus aureus, isolated from milk samples of dairy-cows with staphylococcic mastitis from five agricultural enterprises, 68 p. c. could be typified as bacteriophages. In 42 typified strains, altogether 17 different phage pictures were found, in which case, in the different agricultural enterprises, the number of phage picture fluctuated between 1 and 8. Phage picture 42 D was found and dominated in all the agricultural enterprises. Of the typified strains, 76% could be ranked only into one phage group and 24% in the "M" group (= miscellaneous). Of 32 typified strains, 56.3% belonged to phage group IV, 25% to group III, 12.5% to group I, and 6.2% to group II.     

Phage typization of Staphylococcus aureus strains from staphylococcic mastitis of dairy cows]

Of 62 strains of Staphylococcus aureus, isolated from milk samples of dairy-cows with staphylococcic mastitis from five agricultural enterprises, 68 p. c. could be typified as bacteriophages. In 42 typified strains, altogether 17 different phage pictures were found, in which case, in the different agricultural enterprises, the number of phage picture fluctuated between 1 and 8. Phage picture 42 D was found and dominated in all the agricultural enterprises. Of the typified strains, 76% could be ranked only into one phage group and 24% in the "M" group (= miscellaneous). Of 32 typified strains, 56.3% belonged to phage group IV, 25% to group III, 12.5% to group I, and 6.2% to group II.