Newcastle Disease Vaccine, Inactivated

(Ph Eur monograph 0870)

 

Ph Eur


 

 

Definition

 

Newcastle disease vaccine (inactivated) [also known as avian paramyxovirus 1 vaccine (inactivated) for vaccines intended for some species] consists of an emulsion or a suspension of a suitable strain of Newcastle disease virus (avian paramyxovirus 1) that has been inactivated in such a manner that immunogenic activity is retained.

 

Production

 

The virus is propagated in embryonated eggs from healthy flocks or in suitable cell cultures (5.2.4).

 

The test for inactivation is carried out in embryonated eggs or suitable cell cultures and the quantity of inactivated virus used is equivalent to not less than ten doses of vaccine. No live virus is detected.

 

The vaccine may contain an adjuvant.

 

CHOICE OF VACCINE COMPOSITION

 

The vaccine is shown to be satisfactory with respect to safety (5.2.6) and immunogenicity (5.2.7) for each species and category of birds for which it is intended. The following tests may be used during demonstration of immunogenicity.

 

Immunogenicity

 

For domestic fowl, the test with virulent challenge (test B) described under Potency is suitable for demonstrating immunogenicity. For other species of birds (for example, pigeons or turkeys), test C described under Potency is suitable for demonstrating immunogenicity.

 

BATCH TESTING

 

Batch potency test

 

For vaccines used in domestic fowl

 

Carry out test A described under Potency but, if the nature of the product does not allow valid results to be obtained with test A or if the batch does not comply with test A, carry out test B. A test using fewer than twenty birds per group and a shorter observation period after challenge may be used if this has been shown to give a valid potency test.

 

For vaccines used in species other than domestic fowl

 

Carry out a suitable validated test for which a satisfactory correlation has been established with test C described under Potency, the criteria for acceptance being set with reference to a batch that has given satisfactory results in the latter test. A test in chickens from a flock free from specified pathogens (5.2.2) and consisting of a measure of the serological response to graded amounts of vaccine (for example, 1/25, 1/50 and 1/100 dose with serum sampling 17 to 21 days later) may be used.

 

Identification

 

When injected into animals free from antibodies against Newcastle disease virus, the vaccine stimulates the production of such antibodies.

 

Tests

 

Safety

 

If the vaccine is intended for use in domestic fowl, vaccinate ten chickens from a flock free from specified pathogens (5.2.2). If the vaccine is not for use in domestic fowl, use ten birds of one of the species for which the vaccine is intended, free from antibodies against Newcastle disease virus. Inject twice the vaccinating dose by a recommended route into each of ten birds, 14 to 28 days old. Observe the birds for 21 days. No abnormal local or systemic reaction occurs.

 

Inactivation

 

Inject two-fifths of a dose into the allantoic cavity of each of ten embryonated hen eggs, 9 to 11 days old, from flocks free from specified pathogens (5.2.2) (SPF eggs) and incubate. Observe for 6 days and pool separately the allantoic fluid from eggs containing live embryos, and that from eggs containing dead embryos, excluding those dying within 24 h of the injection. Examine embryos that die within 24 h of injection for the presence of Newcastle disease virus: the vaccine does not comply with the test if Newcastle disease virus is found.

 

Inject into the allantoic cavity of each of ten SPF eggs, 9 to 11 days old, 0.2 ml of the pooled allantoic fluid from the live embryos and, into each of ten similar eggs, 0.2 ml of the pooled fluid from the dead embryos and incubate for 5 to 6 days. Test the allantoic fluid from each egg for the presence of haemagglutinins using chicken erythrocytes.

 

The vaccine complies with the test if there is no evidence of haemagglutinating activity and if not more than 20 per cent of the embryos die at either stage. If more than 20 per cent of the embryos die at one of the stages, repeat that stage; the vaccine complies with the test if there is no evidence of haemagglutinating activity and not more than 20 per cent of the embryos die at that stage.

 

Antibiotics may be used in the test to control extraneous bacterial infection.

 

Extraneous agents

 

Inject a double dose by a recommended route into each of ten chickens, 14 to 28 days old and from a flock free from specified pathogens (5.2.2). After 3 weeks, inject one dose by the same route. Collect serum samples from each chicken 2 weeks later and carry out tests for antibodies to the following agents by the methods prescribed for chicken flocks free from specified pathogens (5.2.2): avian encephalomyelitis virus, avian infectious bronchitis virus, avian leucosis viruses, egg-drop syndrome virus, avian bursal disease virus, avian infectious laryngotracheitis virus, influenza A virus, Marek's disease virus. The vaccine does not stimulate the formation of antibodies against these agents.

 

Sterility

 

The vaccine complies with the test for sterility prescribed in the monograph on Vaccines for veterinary use (0062).

 

POTENCY

 

For vaccines for use in domestic fowl carry out test A. If an unsatisfactory result is obtained with test A but a satisfactory result is obtained with test B, the vaccine complies with the requirements. For vaccines for use only in other species, such as pigeons, carry out test C.

 

A.    Inject intramuscularly into each of not fewer than ten chickens, 21 to 28 days old and from a flock free from specified pathogens (5.2.2), a volume of the vaccine equivalent to 1/50 of a dose. 17 to 21 days later, collect serum samples from each vaccinated chicken and from each of not fewer than five control chickens of the same age and from the same source. Measure the antibody levels in the sera by the haemagglutination-inhibition (HI) test using the technique described below or an equivalent technique with the same numbers of haemagglutinating units and red blood cells. The test system used must include negative and positive control sera, the latter having an HI titre of 5.0 log2 to 6.0 log2.

 

The vaccine complies with the test if the mean HI titre of the vaccinated group is equal to or greater than 4.0 log2 and that of the unvaccinated group is 2.0 log2 or less. If the HI titres are not satisfactory, carry out test B.

 

Haemagglutination-inhibition test

 

Inactivate the test sera by heating at 56C for 30 min. Add 0.025 ml to the first row of wells in a microtitre plate. Add 0.025 ml of a buffered 9 g/l solution of sodium chloride R at pH 7.2 to pH 7.4 to the rest of the wells. Prepare twofold dilutions of the sera across the plate. To each well add 0.025 ml of a suspension containing 4 haemagglutinating units of inactivated Newcastle disease virus. Incubate the plate at 4C for 1 h. Add 0.025 ml of a 1 per cent V/V suspension of red blood cells collected from chickens, 3 to 4 weeks old and free from antibodies against Newcastle disease virus. Incubate the plate at 4C for 1 h. The HI titre is equal to the highest dilution that produces complete inhibition.

 

B.    Use chickens 21 to 28 days old and from a flock free from specified pathogens (5.2.2). For vaccination, use not fewer than three groups, each of not fewer than twenty chickens; keep a group of ten chickens as controls. Choose a number of different volumes of the vaccine corresponding to the number of groups: for example, volumes equivalent to 1/25, 1/50 and 1/100 of a dose. Allocate a different volume to each vaccination group. Inject intramuscularly into each chicken the volume of vaccine allocated to its group. 17 to 21 days later, challenge all the chickens by intramuscular injection of 6 log10 embryo LD50 of the Herts (Weybridge 33/56) strain of Newcastle disease virus. Observe the chickens for 21 days. Calculate the PD50 by standard statistical methods from the number of chickens that survive in each vaccinated group without showing any clinical evidence of Newcastle disease during the 21 days. The vaccine complies with the test if the smallest dose stated on the label corresponds to not less than 50 PD50 and the lower confidence limit is not less than 35 PD50 per dose. If the lower confidence limit is less than 35 PD50 per dose, repeat the test; the vaccine must be shown to contain not less than 50 PD50 in the repeat test. The test is not valid unless all the control birds die within 6 days of challenge.

 

C.    Vaccinate not fewer than twenty birds of the target species, free from antibodies against avian paramyxovirus 1, in accordance with the recommendations for use. Maintain as unvaccinated controls a group of not fewer than ten birds of the same age, from the same source and free from antibodies against avian paramyxovirus 1. The test is invalid if serum samples obtained at the time of the first vaccination show the presence of antibodies against avian paramyxovirus 1 in either vaccinates or controls or if tests carried out at the time of challenge show such antibodies in controls. 4 weeks after the last vaccination, challenge each bird intramuscularly with a sufficient quantity of virulent avian paramyxovirus 1. The test is not valid if fewer than 90 per cent of the control birds die or show serious signs of Newcastle disease virus infection. The vaccine complies with the test if not fewer than 90 per cent of the vaccinated birds survive and show no serious signs of avian paramyxovirus 1 infection.

 

 

 


Ph Eur