Inactivated oil emulsion vaccines from selected clones of Newcastle disease virus

The immunogenicity of oil emulsion (OE) vaccines prepared from two selected clones of a Nigerian strain of Newcastle disease virus and two commercial vaccine strains were compared. Geometric mean haemagglutination inhibition titre was lowest in OE-Lasota, although all four vaccines gave 100% protection against clinical Newcastle disease. The use of OE vaccines is recommended for commercial use in Nigeria.     

Determination of hemagglutination activity recovered from oil-emulsion Newcastle disease vaccines as a prediction of efficacy

Hemagglutination (HA) activity was recovered from the aqueous phases of commercially and experimentally prepared oil-emulsion (OE) Newcastle disease virus (NDV) vaccines using two methods: aqueous partition and freeze-thaw. Quantitation of the HA activity retrieved by the aqueous partition technique was directly related to the degree of protection conferred to chickens against a strain of velogenic viscerotropic (VV) NDV in nine of the ten vaccines analyzed. One of the ten vaccines yielded high levels of retrieved HA activity but induced low hemagglutination-inhibition (HI) antibody levels and low levels of protection. Therefore, the retrieval and quantitation of HA activity from OE NDV vaccines using the partition technique provides a useful adjunct to vaccine testing methods that doesn't require vaccination and challenge trials. The freeze-thaw method did not yield measurable HA titers for all vaccines with high efficacy, so its use should be restricted to only those vaccines for which it has been demonstrated to be suitable.     

Efficacy of genotype-matched Newcastle disease virus vaccine formulated in carboxymethyl sago starch acid hydrogel in chickens vaccinated via different routes

BackgroundThe commercially available Newcastle disease (ND) vaccines were developed based on Newcastle disease virus (NDV) isolates genetically divergent from field strains that can only prevent clinical disease, not shedding of virulent heterologous virus, highlighting the need to develop genotype-matched vaccinesObjectivesThis study examined the efficacy of the NDV genotype-matched vaccine, mIBS025 strain formulated in standard vaccine stabilizer, and in carboxymethyl sago starch-acid hydrogel (CMSS-AH) following vaccination via an eye drop (ED) and drinking water (DW).MethodsA challenge virus was prepared from a recent NDV isolated from ND vaccinated flock. Groups of specific-pathogen-free chickens were vaccinated with mIBS025 vaccine strain prepared in a standard vaccine stabilizer and CMSS-AH via ED and DW and then challenged with the UPM/NDV/IBS362/2016 strain.ResultsChickens vaccinated with CMSS-AH mIBS025 ED (group 2) developed the earliest and highest Hemagglutination Inhibition (HI) NDV antibody titer (8log₂) followed by standard mIBS025 ED (group 3) (7log₂) both conferred complete protection and drastically reduced virus shedding. By contrast, chickens vaccinated with standard mIBS025 DW (group 5) and CMSS-AH mIBS025 DW (group 4) developed low HI NDV antibody titers of 4log₂ and 3log₂, respectively, which correspondingly conferred only 50% and 60% protection and continuously shed the virulent virus via the oropharyngeal and cloacal routes until the end of the study at 14 dpc.ConclusionsThe efficacy of mIBS025 vaccines prepared in a standard vaccine stabilizer or CMSS-AH was affected by the vaccination routes. The groups vaccinated via ED had better protective immunity than those vaccinated via DW.     

Prevalence and outcome of routine and emergency reproductive surgery in female pet rats presented to a veterinary teaching hospital

BackgroundReproductive tract disease is not commonly reported in pet rats. Prevalence, disease identification, outcome and treatment of reproductive tract diseases in pet rats has not been reported.MethodsRecords from all female rats presented to Oklahoma State University Veterinary Teaching Hospital from 2012-2020 were manually reviewed. Animals undergoing ovariohysterectomy (OVH) and/or ovariectomy (OE) were eligible for inclusion in the study.ResultsOf 42 female pet rats, 7 rats (16.6%) underwent routine OHE/OE and 3 rats (7.1%) underwent non-elective (emergent) OHE for treatment of reproductive disease, including dystocia, vaginal prolapse and hemorrhagic endometritis. Of the non-elective OHE procedures, one of the three rats survived surgery and the other two died. Postmortem examinations demonstrated respiratory disease in the non-survivors. All the rats that presented for elective OHE/OE survived to discharge.Conclusions and clinical relevanceReproductive disease in female rats is relatively frequent and herein we described a condition previously unreported in pet rats (vaginal prolapse). This report adds to the body of evidence that supports elective reproductive surgery for pet rats.     

Investigations on live vaccines against infectious bursal disease of chicks

Summary

Four live virus vaccines against Infectious Bursal Disease (IBD) were studied with regard to their safety, immune response and applicability. None of the vaccines caused clinical symptoms or had an adverse impact on bodyweight. Differences between these vaccins were observed in their effect on the Bursa/ Bodyweight Ratio and the severity of the microscopical lesions of the bursa Fabricii. The immunosuppressive effect of IBD vaccination at one day of age on the response to Newcastle disease vaccine applied was rather low.

Three of the four vaccines induced antibodies associated with protection against challenge. Vaccination of SPF rearing chickens by drinking water at an age of 15 weeks produced an antibody response (Agar Gel Precipitin Test) whereas at an age of 23, 32 and 60 weeks it did not. Chickens of all age groups responded serologically to an intramusculair vaccination.

A correlation was found between the immunological response and the effect of the vaccines on the bursa Fabricii.     

Optimization of hydrophile-lipophile balance for improved efficacy of Newcastle disease and avian influenza oil-emulsion vaccines

Preparations of inactivated Newcastle disease (ND) and avian influenza (AI) oil-emulsion vaccines with surfactant hydrophile-lipophile-balance (HLB) values between 4.3 and 9.5 were evaluated for their efficacy in broiler-type white rock chickens. Chickens were vaccinated at 3-4 weeks of age and bled at 2-week intervals over 8 weeks. Post-vaccinal hemagglutination-inhibition (HI) geometric mean titers (reciprocals) ranged from 197 to 485 for ND vaccines and from 184 to 1040 for AI vaccines. Based on the HI response, an HLB value of 7.0 induced the greatest stimulation of antibody titers. Ten percent surfactant in the oil phase of the vaccines induced maximum titers at this HLB. The oil:aqueous ratios of the vaccines did not greatly influence the overall serologic response when the vaccines had an HLB of 7.0. These results indicate that manipulating surfactant HLB values of OE vaccine may maximize the HI response in broilers.     

Antigen quantification as in vitro alternative for potency testing of inactivated viral poultry vaccines

Abstract

Routine batch control of licensed inactivated viral vaccines for poultry usually includes a potency assay as a measure of vaccine efficacy. Potency assays often consist of vaccination‐challenge experiments in the target species or in laboratory animals. Instead of measuring the protection of vaccinated animals against virulent pathogens, the serological response after vaccination can be quantified for some vaccines. In vitro antigen quantification assays would be attractive alternatives for the current potency assays because the time and costs involved could be greatly reduced and animal use could be avoided. Such in vitro assays will only be acceptable when the correlation between results and efficacy or potency has been demonstrated convincingly.

The results of our studies on antigen quantification assays indicate that, in principle, quantification of viral antigens from inactivated oil‐adjuvanted vaccines is feasible and reproducible using specially developed antigen capture ELISAs in combination with specific software for statistical analysis of the ELISA data. We have developed methods to quantify the haemagglutination‐neuraminidase (HN) and fusion (F) proteins of Newcastle disease virus (NDV), the viral protein 3 (VP3) of the infectious bursal disease virus (IBDV), and the spike‐1 (S1) protein of the infectious bronchitis virus (IBV). Vaccination experiments with inactivated ND vaccines indicate that the in vitro quantified HN‐ or F‐proteins of NDV are reliable indicators of the serological response after vaccination.     

The limitations of a feed/water based heat-stable vaccine delivery system for Newcastle disease-control strategies for backyard poultry flocks in sub-Saharan Africa

Backyard poultry are a major contributor to egg and meat consumption in sub-Saharan Africa and an important source of income for many rural producers. Production throughout Africa is severely constrained by continuing outbreaks of Newcastle disease. The livestock-service sector lacks the resources and infrastructure to control Newcastle disease in extensive flocks without the active participation of producers. The development of ‘heat-stable’ Newcastle disease vaccines offers a potential solution. Trials over the last two decades have examined the effectiveness of heat-stable vaccines in both controlling Newcastle disease and in involving the rural community in control strategies. Constraints highlighted include the reliability of the vaccines using alternative delivery methods and the capacity of rural communities to apply those methods. The search for appropriate Newcastle disease-control strategies in extensive poultry systems should focus on policies and methodologies that incorporate the wider concerns and priorities of extensive producers.     

Efficacy of avridine as an adjuvant for Newcastle disease virus antigen in chickens

Avridine, a lipoidal amine with interferon-inducing and adjuvant properties, was an effective adjuvant for Newcastle disease antigen (NDA) in chickens. Eleven vaccine lots were evaluated: 2 commercial water-in-oil vaccines, 4 experimental oil emulsion vaccines, 4 avridine-containing vaccines, and a control lot of nonadjuvanted antigen. Avridine significantly enhanced the immunologic responses of chickens against NDA. Chickens vaccinated with the avridine-containing vaccines had significantly higher antibody titers (hemagglutination inhibition) than did chickens vaccinated with the commercial vaccines. Experimental oil emulsion vaccines prepared from the same antigens as avridine-adjuvanted vaccines induced higher hemagglutination inhibition antibody titers after primary but not after booster vaccination. Use of avridine as an adjuvant for NDA in vaccines for chickens induced immunologic protection rates similar to those induced by oil emulsion vaccines, without causing the reactogenic and tissue residue problems associated with the use of oil vaccines in chickens.     

Efficacy of viable and inactivated Newcastle disease virus vaccines in turkeys

Market turkeys spray-vaccinated at 20 days of age with viable Newcastle disease virus (NDV) vaccine and challenged 7 weeks postvaccination failed to yield NDV by tracheal swabbing 4 days postchallenge but demonstrated serologic evidence of infection. Birds vaccinated subcutaneously with inactivated oil-emulsion (OE) NDV vaccine had virologic and serologic evidence of infection. Breeder hens vaccinated by spray with commercial La Sota vaccine at 19 weeks of age and revaccinated subcutaneously with OE vaccine at 32 weeks of age had an adequate level of resistance against a drop in egg production but demonstrated serologic evidence of infection when challenged with velogenic NDV at 38 weeks of age.     

Comparison of Newcastle disease vaccines by serology using serum,tears and feather pulp samples

Seroconversion of 3 lentogenic commercial Newcastle disease (ND) vaccines and experimental V₄ vaccines was compared based on the haemagglutination inhibition (HI) test against ND. It was found that for primary vaccination all the vaccines produced similar response but for secondary vaccinations V₄ and LaSota were better than RDVF. Eighty-five samples each of serum, tears and feather pulp were collected from respective birds and antibody assessment was done against ND by HI test. The geometric mean HI titres (GMT) of serum samples were highest followed by tears and feather pulp samples before vaccination and 3 weeks after vaccination by oculonasal route and the difference was statistically significant (p<0.01). Three weeks after booster vaccination by oculonasal route, however, the GMT of serum samples were highest followed by feather pulp and tears samples. The ease of collection of feather pulp samples and their role in ND serology is discussed.     

Immunogenicity and protective efficacy of virosome based vaccines against Newcastle disease

Virosome based vaccines against Newcastle disease (ND) were prepared and evaluated for their immunogenicity and protective efficacy in chickens. Envelop of Newcastle disease virus (NDV) was solubilised with Triton X-100 to yield virosomes which were later on encapsulated in poly-lactide-co-glycolide (PLG) microspheres. The birds were immunized intranasally with virosomes or PLG microspheres encapsulated virosomes, and efficacy of these preparations was compared with commercial LaSota vaccine. The preparations protected the chickens against virulent virus challenge infection, however the microencapsulated virosome vaccine gave slightly lesser degree of protection than non encapsulated counterpart. The humoral and cell mediated immune response generated as well as the protection afforded by virosome preparations were found to be comparable with LaSota vaccine. The results substantiate the potential of virosome based vaccines to provide high level of immunity and protection against Newcastle disease.     

Association of PRLR,IGF1, and LEP genes polymorphism with milk production and litter size in Egyptian Zaraibi goat

Tropical Animal Health and Production - The co-administration of commercial live fowlpox (FP) and Newcastle disease (ND) vaccines when given by non-invasive (needle-free) routes was demonstrated to...     

The limitations of a feed/water based heat-stable vaccine delivery system forNnewcastle disease-control strategies for backyard poultry flocks in sub-Saharan Africa

Backyard poultry are a major contributor to egg and meat consumption in sub-Saharan Africa and an important source of income for many rural producers. Production throughout Africa is severely constrained by continuing outbreaks of Newcastle disease. The livestock-service sector lacks the resources and infrastructure to control Newcastle disease in extensive flocks without the active participation of producers. The development of 'heat-stable' Newcastle disease vaccines offers a potential solution. Trials over the last two decades have examined the effectiveness of heat-stable vaccines in both controlling Newcastle disease and in involving the rural community in control strategies. Constraints highlighted include the reliability of the vaccines using alternative delivery methods and the capacity of rural communities to apply those methods. The search for appropriate Newcastle disease-control strategies in extensive poultry systems should focus on policies and methodologies that incorporate the wider concerns and priorities of extensive producers.     

Laboratory trials with inactivated vaccines against Escherichia coli (O2:K1) infection in fowls.

Laboratory trials were carried out with an O2:K1 vaccine prepared with either the Freund's complete or incomplete adjuvant. Both types of vaccine administered subcutaneously were highly effective against a challenge with the vaccine strain within three to four weeks after vaccination at two to three weeks of age. The complete adjuvant vaccine was more effective than the incomplete adjuvant vaccine when administered to chickens of an earlier age, and in the rate of development and duration of immunity. The efficacy of both vaccines was unimpaired by their incorporation with the Newcastle disease oil adjuvant (inactivated) vaccine (Newcadin). The use of an oil adjuvant vaccine was not found to affect the rate of growth adversely or to produce any other reaction prejudicial to its commerical application. The efficacy of the vaccines was unimpaired by their incorporation with Newcastle disease oil adjuvant (inactivated) vaccine (Newcadin) thus demonstrating the possibility of producing a combined Escherichia coli/Newcastle disease virus vaccine.     

The immunodepressive effect of infectious bursal agent on vaccination against Newcastle disease.

Immunodepression due to an infectious bursal agent (IBA) infection depends on the age of the birds, the time of Newcastle disease (ND) vaccination and the IBA strain used. The immunodepressive effect of IBA on ND vaccination can be avoided by vaccinating the chicks against ND at day old or by using attenuated strains of IBA in all commercial vaccines.     

PATHOGENICITY AND IMMUNOSUPPRESSIVE PROPERTIES OF INFECTIOUS BURSAL DISEASE VIRUS FIELD ISOLATES AND COMMERCIAL VACCINES IN INDIA

The pathogenicity and immunosuppressive properties of two field isolates of infectious bursal disease virus (IBDV) and five commercial IBDV live virus vaccines marketed in India were evaluated in this study. The pathogenicity of the wild type viruses and vaccines were based on mortality, the bursa:body weight ratio and microscopic lesions in the bursa in 3-week-old chicks that received these viruses. The immunosuppressive effects of these viruses were evaluated by measuring the antibody responses to sheep red blood cells, Brucella abortus plain antigen and Newcastle disease virus (NDV) vaccine in one-day-old chicks. One field isolate (N35/93) was found to be more pathogenic and immunosuppressive than the other (N45/92) while none of the commercial mild Lukert type vaccines were found to be pathogenic. One of the vaccine strains marked as Mild Lukert type was highly immunosuppressive; one was moderate and one could be classified as mild. Both the intermediate vaccines tested were highly immunosuppressive.     

Similarity of avian paramyxovirus serotype 1 isolates of low virulence for chickens obtained from contaminated poultry vaccines and from poultry flocks

At present Denmark has the status of a 'non-vaccinating' country for Newcastle disease and its poultry population should therefore be free of antibodies to avian paramyxovirus 1 (APMV-1). Three live avian vaccines against infectious bronchitis, avian encephalomyelitis, and chick anaemia which had been found to be contaminated with APMV-1 viruses of low virulence for chickens were examined. The vaccines were produced by the same company and the affected batches had been used in Denmark in 1996/97. Furthermore, APMV-1 isolates of low virulence were obtained from three commercial broiler breeder flocks, one of which had been vaccinated with two of the contaminated vaccines. The flocks belonged to the same hatchery organisation. A comparison of viral F0 gene sequences and typing of virus isolates with a panel of monoclonal antibodies showed that the vaccine and field isolates were identical.     

THE SEROLOGICAL RESPONSE OF CHICKENS TO OIL EMULSION VACCINES CONTAINING THE V4 STRAIN OF NEWCASTLE DISEASE VIRUS

SUMMARY Experiments were conducted with vaccines containing the V₄ strain of Newcastle disease virus (NDV). Both living aqueous vaccines and vaccines consisting of virus incorporated in an oil emulsion were used. The calculated dose of virus contained in the oil emulsion vaccine was 10^8,7 50% embryo infectious doses (EID₅₀) per bird dose. Haemagglutinin inhibition (HI) antibody levels of 8 are presumed protective. One-day-old chicks with low levels of maternal antibody were vaccinated intraocularly with 10^6,3EID₅₀ of live vaccine, and concurrently with oil emulsion vaccine. Presumed protective levels of antibody were present at two weeks post vaccination and were maintained for at least seven weeks longer. When adult birds 15 weeks old with no previous exposure to NDV were vaccinated intraocularly with 10^6,7EID₅₀ per bird, protective levels of antibody were produced within a week. Unvaccinated birds put in contact with the vaccinated birds produced similar antibody levels within 14 days. Revaccination with oil emulsion vaccine after antibody levels had fallen resulted in a rapid response with high levels of antibody. When antibody-free adult commercial birds with an unknown history of exposure to NDV were vaccinated intramuscularly with oil emulsion vaccine, high antibody levels were produced for at least 21 weeks. Concurrent intraocular inoculation with 10^7,0EID₅₀ live virus did not enhance the response. Natural infection of unvaccinated birds occurred during the experiment. This was detected by the presence of HI antibody levels of short duration. When antibody-free commercial birds were inoculated intramuscularly with oil emulsion vaccine containing 10^6,0, 10^7,0, or 10^8,0EID₅₀ per bird dose, 100% of birds inoculated with the highest dose produced presumed protective levels of antibody within two weeks, as compared with a 5-week delay when using the 10^7,0EID₅₀ per bird dose.     

Immune responses induced by DNA vaccines encoding Newcastle virus haemagglutinin and/or fusion proteins in maternal antibody-positive commercial broiler chicken

1. The immune responses induced by recombinant plasmids containing Newcastle disease virus (NDV) F (pVAX.nd.f) or HN (pcDNA.nd.hn) genes separately or in combination in bi-cistronic (pIRES.nd.hn.f) constructs were evaluated in maternal antibody-positive commercial chicks. 2. Immunofluorescence and immunoperoxidase tests demonstrated the expression of both F and HN proteins in Vero cells. Real-time PCR analysis revealed the expression of HN and/or F genes in muscle, peripheral blood mononuclear cells (PBMC), spleen and liver after immunisation. 3. Chicks inoculated intramuscularly thrice (two booster doses) with pVAX.nd.f and pcDNA.nd.hn did not develop detectable haemagglutination inhibiting (HI) antibodies. In contrast, an increase in a NDV-specific cell-mediated immune response was demonstrated. 4. After challenge with virulent NDV, chicks immunised with the recombinant plasmids as well as those in control groups succumbed to Newcastle disease. 5. Based on these results, it is concluded that DNA vaccines containing HN and/or F genes fail to protect commercial chicks, possibly due to interference from maternal antibodies.