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Effect of some chemicals and natural products on Newcastle disease virus vaccines prepared in Egypt
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Abstract: Viral diseases in general are difficult in their treatment owing to their intracellular tropism of the infected hosts. The currently available antiviral compounds of synthetic , chemicals and antibiotics have major drawback, such as narrow spectrum of activity limited therapeutic usefulness and variable degrees of toxicity. Therefore, any new agent that could overcome some or all theses disadvantages would be very useful.
Natural products are preferable over synthetic therapeutic drugs as a source for antiviral agents. The main purpose of this study was to search in the field of secondary plant metabolites which might be used as antivirals.
In the present investigation, nine plant extracts of the native Egyptian flora were tested for monitoring their antiviral and/or the inhibitory effect on different vaccinal strains of NDV.
The obtained results were as follows :
1) The safety doses of nine plant extracts when inoculated into 9-11 day old embryonated chicken eggs were determined it was ranging from 10-1 to 10-4 for the nine different extracts.
2) The safety doses of the plant extracts were mixed with different dilutions of vaccinal strains of NDV to determine the antiviral effect of each mixture on NDV in ovo. The results showed that only one sample gave 100% inhibition when tested with all virus strains. Another two samples were potent extracts and inhibited viral infectivity with margined effect. Three samples showed little variable inhibitory effect, and the last three samples had no significant effect.
3) Moreover another experiment was carried out by using serial dilutions of downward the safety dose of each plant extract and mixing it with a consultant dilution of different strains of NDV. The minimum inhibitory concentration (MIC) for each extract was determined. It was ranged from 10-2 to 10-7 for all the nine plant extracts. Basalin and Santin were the only extracts which abolished haemaggulination capacity of B1 strain. Peculiarly, all plant extracts showed higher efficacy on inhibiting the hamagglutination capacity of Lasota strain.
4) Back titration of chorio-allantoic fluids of extracts No. IV, V and VI mixed with both F. and K. strains of NDV. The resulted mixtures revealed the following results:
Plant extraction Santin showed 100% antiviral activity on both F and K.strains of NDV. Plant extract Cynarin showed about 25 % viral inhibitory effect on both F and K. strains of NDV. Extract Labinin exhibited 40 % and 25 % inhibitory effect on both F and K.strains respectively.
5) Confirmatory experiment was carried by mixing the safety doses of Santin, Cynarin and Labanin with the field doses F and K. vaccinal strains of NDV. Both mixtures were used for vaccination of chicks and chickens by eye drop and Intramuscular routes with F and K. strains respectively. The total immunoglobulins were estimated 21 days post vaccination. The results showed a decrease in immunoglobulins, such decrease was higher in case of Santin than the other two extracts.
6) When the afore mentioned chickens were challenged 21 days post vaccination, the obtained results confirmed the antiviral effect of the three extracts specially when applied with the vaccine of F strain for baby chicks. On the other hand, the same extracts with Komarov strain. Showed significant variation in the antiviral activity of plant extracts.
In spite of the obtained results, further investigations should be carried out e.g. use of tissue culture in order to explain the mode of action of the plant extracts on NDV, infectivity cycle, applying the extracts before and after viral infection. The usefulness of application of these plant extracts for prevention and/or remedy of NDV epidemic in Egypt should be assessed by further investigations.
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| Publication year |
1989
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| Availability location |
مكتبة معهد بحوث الامصال واللقاحات البيطرية
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| Availability number |
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| Organization Name |
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| Country |
Egypt
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| Author(s) from ARC |
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| External authors (outside ARC) |
أبراهيم محمد حسن سكر
وكيل كلية الطب البيطرى جامعة اسيوط
مصطفى عبد المطلب شحاته
كلية طب بيطرى جامعة اسيوط
نادية محمد حسن
معهد بحوث الأمصال واللقاحات البيطرية
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AGROVOC
TERMS |
Newcastle disease.
Newcastle disease virus.
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| Proposed Agrovoc |
Viral vaccines;
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| Publication Type |
PhD Thesis
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