AN ASSESSMENT OF THE AUSTRALIAN V4 STRAIN OF NEWCASTLE DISEASE VIRUS AS A VACCINE BY SPRAY, AEROSOL AND DRINKING WATER ADMINISTRATION

SUMMARY An Australian strain of Newcastle disease virus, was evaluated for use as a vaccine following its administration by drinking water, aerosol and spray to chickens at 1 and 21 days of age. Haemagglutination inhbition antibody was produced and persisted for 11 weeks. Aerosol vaccination induced higher levels of haemagglutination inhibition antibody than the other methods of vaccination. No respiratory disease was observed following vaccination. Chickens vaccinated by aerosol and spray were fully protected when challenged at 5, 7 and 11 weeks of age with virulent Newcastle disease virus. Mortality of 10 to 30 per cent was observed in chickens vaccinated by drinking water and intranasally following challenge.     

Newcastle disease vaccination: A comparison of vaccines and routes of administration in Pakistan

Twelve-day-old chickens were vaccinated once with different Newcastle disease (ND) vaccines ( F, La Sota and Mukteswar) by two different routes (intraocular and drinking water). Chickens from a seventh group were uninoculated controls. At weekly intervals for 7 weeks after vaccination, 20 chickens from each vaccinated group and 20 chickens from the control group were examined for the production of haemagglutination-inhibition (HI) antibodies and for protection as assessed after challenge with velogenic, viscerotropic ND virus.

La Sota ND vaccine used intraocularly ranked the best and Mukteswar vaccine by the drinking water route the worst for their HI antibody titres prior to challenge. Differences between the treatments in protection were examined. For all three vaccines intraocular vaccine produced higher protection than drinking water vaccine. An inverse relationship between prechallenge and postchallenge HI titres was also recorded.     

Protective antibody response produced by the chickens vaccinated with green coloured thermostable Newcastle disease virus

The efficacy of green-coloured (GC) I-2 Newcastle disease vaccine was determined in the present study. I-2 vaccine was mixed with a green coloured dye and stored at 4°C for 6 months while assayed for the virus infectivity at a monthly interval. Chickens were vaccinated with the GC vaccine by eye drop. Serum samples were collected from all birds before and after vaccination at weekly interval for 4 weeks and tested for haemagglutination-inhibition (HI) antibody against Newcastle disease virus (NDV). These chickens were challenged with NDV virulent strain four weeks after vaccination. The results showed that there was no difference between the infectivity titres of GC and uncoloured vaccines. However, chickens vaccinated with GC vaccine produced higher HI antibody titres than chickens vaccinated with uncoloured vaccine. Results from the challenge trial showed that all vaccinated chickens survived whereas all unvaccinated chickens died. The findings from this study have shown that the GC vaccine is safe and produced protective antibodies against NDV in vaccinated chickens. Wambura, P. N., 2008. Protective antibody response produced by the chickens vaccinated with green coloured thermostable Newcastle disease virus. Tropical Animal Health and Production.     

THE SEROLOGICAL RESPONSE OF CHICKENS TO AUSTRALIAN LENTOGENIC STRAINS OF NEWCASTLE DISEASE VIRUS

SUMMARY: Australian lentogenic Newcastle disease viruses were evaluated as uninactivated vaccines in Australian chickens, the response being evaluated by the production of haemagglutination-inhibition (HI) antibodies. Two viruses, V4 and PM9, induced high levels of antibody and were readily transmissible between chickens by contact exposure. Three other viruses were poorly immunogenic and poorly transmissible. Chickens vaccinated intramuscularly with the V4 strain produced higher HI antibody titres than chickens vaccinated by the orotracheal, intranasal and intraocular routes. HI antibody titres in chickens vaccinated with the V4 strain reached peak levels 3 to 5 weeks after vaccination and waned considerably during the next 2 to 4 weeks. However, low levels of HI antibody persisted for at least 36 weeks after vaccination. Intramuscular vaccination with the V4 strain of one-day-old chicks lacking maternal antibody to Newcastle disease virus resulted in 42–70% mortality and the survivors developed very high titres of HI antibody. Similar chickens inoculated orotracheally showed signs of depression and developed high titres of HI antibody, but there were no mortalities. Chickens 1-, 2-, 3- and 4-weeks-old and lacking maternally derived HI antibody to Newcastle disease virus suffered no adverse reaction to intramuscular or orotracheal vaccination. The antibody response of the 1-week-old chickens was considerably poorer than that of the older chickens. Following orotracheal vaccination with the V4 strain, chickens with low levels of maternally derived antibody responded with low levels of HI antibody. On the other hand, in the progeny of hens hyperimmunised with the V4 strain the production of active antibody following orotracheal vaccination was delayed until the level of passive antibody had declined considerably. There was no response to intramuscular vaccination in congenitally hyperimmune chickens. The minimum HI antibody inducing dose of V4 vaccine, when measured 3 weeks after vaccination of 6-weeks-old chickens, was 10^5.6 50% egg infectious doses.     

Comparison of two infectious bursal disease vaccine strains: efficacy and potential hazards in susceptible and maternally immune birds.

Two infectious bursal disease vaccines were administered to separate groups of maternally immune and susceptible chickens at various ages. Vaccine B caused no damage to the bursae of chickens examined histologically at nine and 20 days after vaccination. The bursae of chickens given vaccine A were shown to be severely damaged when similarly examined. Both vaccines protected all the susceptible groups against challenge, but only vaccine A protected the groups of maternally immune chickens. Susceptible chickens vaccinated at one day of age with vaccine A showed a lowered response to Hitchner B1 Newcastle disease vaccine given at 14 days of age, judged by the haemagglutination-inhibition response and Newcastle disease challenge. The performance of the Newcastle disease vaccine was not affected in chickens given vaccine B. Bedding used by birds given vaccine A was shown to be capable of transmitting vaccinal virus to susceptible chickens, causing severe bursal damage.     

The serological responses of chickens to mass vaccination with a live V4 Newcastle disease virus vaccine in the field and in the laboratory 1. Meat chickens

Meat chickens on commercial broiler farms were vaccinated once at 1 to 15 days of age with a live V4 Newcastle disease virus (NDV) vaccine administered by drinking water, aerosol or coarse spray. Hatchmates were housed and similarly vaccinated in laboratory isolation pens. Samples of birds were bled at weekly to fortnightly intervals and the serums tested for haemagglutination inhibiting antibody to NDV. Log2 mean titres of up to 6.26, and assumed protection levels (based on the percentage of birds with log2 titres of 4 or greater) of up to 89%, were obtained in field trials within 4 weeks of vaccination. Differences were observed between the results obtained from parallel field and laboratory trials. The presence of maternal NDV antibody reduced the response to vaccination. The results show that this V4 vaccine can produce an adequate serological response following mass administration to Australian meat chickens housed under commercial conditions.     

Serological response of chickens to oral vaccination with Newcastle disease virus

Conventional Newcastle disease vaccines are not suitable for application to village chickens in tropical countries of Asia. Trials with food-based vaccines are being initiated and the following experiments were performed to evaluate oral vaccination with Newcastle disease virus. Experimental chickens were vaccinated orally with the avirulent V4 strain of Newcastle disease virus and haemagglutination-inhibition antibody responses were measured. V4 virus was introduced into the crop by tube and total faecal output was collected daily and assayed for Newcastle disease virus. Virus was recovered on Days 5 and 6 after vaccination from most chickens that had received 10(7.4) and 10(6.4) 50% egg-infectious doses (EID50) of virus. There was no recovery of virus from birds receiving a lower dose of vaccine. Groups of chickens kept in cages with wire floors were given various doses of vaccine into the crop. Higher antibody titres were achieved with higher doses of virus. This dose responsiveness was not observed when various doses of vaccine were presented on food pellets and the groups of chickens were kept on concrete floors. Similar antibody responses were then seen with nominal doses of 10(5.2) and 10(8.2) EID50 per bird, possibly as a result of excretion and re-ingestion of the vaccine virus. Spread of the vaccine virus was demonstrated when control chickens and chickens receiving 10(7.7) EID50 of V4 virus on food pellets were housed together on a concrete floor. Similar antibody titres were achieved in both vaccinated and in-contact chickens.     

Experimental trials with a thermostable Newcastle disease virus (strain I2) in commercial and village chickens in Tanzania

Antibody responses in indigenous village and commercial chickens vaccinated with 12 thermostable Newcastle disease (ND) vaccine and protection levels against challenge with a virulent field isolate were determined. The antibody response of village chickens vaccinated by eye drop revealed that 30, 60 and 90 days after primary vaccination, the mean log2 HI titres were 6.1, 5.4 and 3.6, respectively, whereas for commercial chickens, the antibody response after 14, 30 and 90 days were 8.2, 5.1 and 4.2, respectively. Village chickens vaccinated orally via drinking water had mean log2 HI titres of 3.4 after 30 days. After booster vaccination, the mean HI titre was 5.4 and 3.3 after 30 and 60 days post-secondary vaccination (i.e. 60 and 90 days after primary vaccination). Antibody response of mean log2 HI titres of 2.6 was recorded 30 days after primary vaccination orally through food; 30 and 60 days after secondary vaccination (i.e. 60 and 90 days after primary vaccination), mean log2 HI titres were 5.3 and 3.2, respectively. All commercial and village chickens vaccinated by eye drop survived the challenge trial whereas village chickens vaccinated through drinking water and food had protection levels of 80% and 60% 30 days after primary vaccination, respectively. However, 30 days after booster vaccination, the protection level was 100%. At 60 days after secondary vaccination, the protection level dropped again to 80% for chickens vaccinated orally. All control chickens used in the challenge trials developed clinical ND and died 3-5 days after inoculation with the virulent virus. Supported by laboratory findings, I2 strain of NDV seemed to be avirulent, immunogenic and highly protective against virulent isolates of NDV. It may be a suitable vaccine to use in village chickens to vaccinate them against ND in rural areas.     

The resistance of meat chickens vaccinated by aerosol with a live V4 Newcastle disease virus vaccine in the field to challenge with a velogenic Newcastle disease virus

Meat chickens housed on a commercial broiler farm in Australia were vaccinated once at 10 to 11 days-of-age by aerosol with live V4 Newcastle disease virus (NDV) vaccine. Groups of vaccinated and unvaccinated birds were flown to Malaysia, where they were challenged with a virulent strain of NDV. Survival rates in vaccinated chickens challenged 7, 14, 21 or 31 d after vaccination were 0.47, 0.77, 0.97 and 0.92, respectively. All unvaccinated chickens died due to Newcastle disease (ND) following challenge. Chickens in Australia and Malaysia were bled and the serums tested for haemagglutination-inhibiting (HI) antibody to NDV. Many vaccinated birds with no detectable antibody, and all birds with a log2 titre of 2 or greater, survived challenge. The results showed that this V4 vaccine induced protective immunity in a significant proportion of chickens within 7 d of mass aerosol vaccination. This early immunity occurred in the absence of detectable circulating HI antibody. Non-HI antibody mediated immunity continued to provide protection up to 31 d after vaccination. Almost all vaccinated birds were protected within 3 w of vaccination. It is concluded that the V4 vaccine is efficacious and could be useful during an outbreak of virulent ND in Australia.     

鸡新城疫（ND）各种免疫程序的测定

本试验进行了三批鸡的免疫研究。第一批试验检测不同类型新城疫疫苗在不同母源抗体水平（高和低）的鸡体上的免疫效果。结果显示,在高母源抗体时免疫,Ｖ４组和油乳剂灭活苗级抗体水平表现较低,而在低母源抗体时免疫,几种疫苗的抗体水平上升得很快,特别Ｌａｓｏｔａ－克隆３０组最明显,而油乳剂灭活苗组的抗体水平保持最长。根据此结果而制定了不同的免疫程序,进行了第二、第三批免疫试验,并分别在４５天龄及７０天龄时进行强     

AEROSOL VACCINATION OF CHICKENS WITH THE V4 STRAIN OF NEWCASTLE DISEASE VIRUS

SUMMARY Two-week-old chickens, free of detectable maternal antibody to Newcastle disease virus (NDV), or with low levels of maternal antibody, were vaccinated with the V4 strain of NDV. Haemagglutination inhibition (HI) antibodies were determined at intervals after vaccination. Two hundred chickens were vaccinated by exposure to an aerosol, a dose of 10⁶ 50% embryo infectious doses (EID⁵⁰) being allowed per chicken. Forty unvaccinated chickens were placed in direct contact with vaccinated chickens. Most of the vaccinated chickens and the incontact chickens had developed HI antibodies of titre ≥ 8 within 2 weeks of vaccination. The HI antibodies in many chickens persisted for at least 8 weeks. Control chickens in a shed 15 metres from the shed containing the vaccinated chickens did not develop HI antibodies to NDV. NDV could be isolated from some vaccinated chickens for 15 days after vaccination. An aerosol dose of 10⁵EID₅₀ per chicken failed to induce a serological response in 2 groups of 40 chickens each. HI antibodies were produced in 1 of 2 groups, each of 40 chickens, vaccinated with 10⁶EID₅₀ and in both of 2 groups of 40 chickens each vaccinated with 10⁷EID₅₀. Duplicate groups of 40 chickens were vaccinated with 10⁶EID₅₀ of V4 virus per chicken administered either as an aerosol, a coarse spray or a droplet placed in the conjunctival sac. HI antibodies were produced in all the groups of chickens.     

The serological responses of chickens to mass vaccination with a live V4 Newcastle disease virus vaccine in the field and in the laboratory 2. Layer pullets

Layer chickens on a commercial started pullet farm were vaccinated once at 31 to 52 days of age by drinking water or aerosol with live V4 Newcastle disease virus (NDV) vaccine. Flockmates which had been rehoused in laboratory isolation pens shortly beforehand were similarly vaccinated. Samples of birds were bled at intervals and the serums tested for haemagglutination inhibiting antibody to NDV. Log2 mean titres of up to 4.88 and assumed protection levels (based on the percentage of birds with log2 titres of 4 or greater) of up to 81%, were obtained in the field trials within 4 weeks of vaccination. A subsequent laboratory trial further compared the response of different breeds of chicken to different routes of vaccination. Differences were observed between breeds, routes of vaccination, and parallel field and laboratory trials. The results show that this V4 vaccine can produce an adequate serological response following mass vaccination of Australian layer pullets housed under commercial conditions, and that care should be exercised in extrapolating results obtained under laboratory conditions.     

Different approaches to the vaccination of free ranging village chickens against Newcastle disease in Qwa-Qwa, South Africa

The aim of this study was to develop a strategy to control Newcastle disease (ND) in free ranging village chickens using the Nobilis ND Inkukhu vaccine (Intervet South Africa). The study was conducted at Thibella village in Qwa-Qwa, South Africa from April 2001 to October 2002. Three different routes of vaccination (administration via eye-drop, drinking water and feed) were investigated. The haemagglutination inhibition (HI) test was conducted monthly in order to measure the antibody response of village chickens after immunization against Newcastle disease. Using a South African isolate of velogenic ND virus, challenge trials were conducted to determine the efficacy of the vaccine. A questionnaire was provided to evaluate perceptions of farmers on vaccinations. The eye-drop vaccination route produced the highest HI titres ranging between 2.7 and 4.4, followed by the drinking water vaccination route with titres ranging between 2.3 and 4.0. The lowest titres were from the feed vaccination route which ranged between 1.6 and 3.0. Following the challenge, the entire control group died on the third and fourth day after infection. However, 70% of the chickens immunized by using either the eye-drop or drinking water route survived the challenge. Only 20% of the chickens from the group immunized through the feed route survived. Evidently both the eye-drop and drinking water routes were efficient in preventing disease. Necropsies showed that vaccinated chickens had mild lesions whilst control chickens had severe lesions compatible with Newcastle disease. The efficacy of the vaccine using either of the routes can be enhanced by administration of booster vaccinations at 3-month intervals during the first year of a vaccination campaign and then at 6-month intervals from the second year onwards. The majority of the owners indicated that they would prefer to vaccinate their flocks using the drinking water route.     

Natural infection of broiler breeder chickens with endemic apathogenic Newcastle disease virus and their subsequent response to vaccination with a live V4 Newcastle disease virus vaccine

Flocks of broiler breeder chickens housed on a commercial farm were monitored from 13 w of age for natural infection with endemic lentogenic Newcastle disease virus (NDV). Seroconversion was first detected at 17 w. By 24 w, all 8 flocks had achieved peak log2 mean haemagglutination inhibiting antibody titres of up to 4.8. Antibody titres then declined and rose again over several months, suggesting cyclic reinfection with NDV. A lentogenic NDV indistinguishable from V4 was isolated from the cloaca of one bird at 18 weeks of age. At 54 weeks of age, 6 of 8 flocks were vaccinated en masse with live V4 NDV vaccine, 3 flocks by drinking water and 3 flocks by aerosol. All flocks were serologically monitored for a further 8 w. Drinking water vaccination induced an anamnestic response in 3 flocks, showing that flocks with pre-existing active immunity to NDV may be successfully vaccinated with V4. However, in all aerosol vaccinated flocks, the procedures failed to induce a response different to that observed in unvaccinated flocks. The serological response to vaccination was greater in sires than in dams.     

Putative protective antibody response following oral vaccination of multi-age free ranging helmeted guinea fowls (<Emphasis Type="Italic">Numida meleagris</Emphasis>) with Newcastle disease virus strain I-2 coated on oiled rice

On-farm study was conducted to determine the efficacy of thermostable Newcastle disease (ND) strain I-2 vaccine coated on oiled rice following oral vaccination of multi-age free ranging helmeted guinea fowls. The results from haemagglutination-inhibition assay showed that 7 days after the guinea fowls were orally vaccinated they seroconverted and attained the geometric mean antibody titre (GMT) of 4.9 log₂ (80%). This antibody titre was above the GMT of 3.0 log₂ which is regarded to be protective against field challenge of ND. Furthermore, the results revealed that 28 days after vaccination, the antibody levels reached GMT of 7.6 log₂ (100%). Moreover, all vaccinated guinea fowls survived the challenge of virulent ND virus whereas all unvaccinated chickens died of ND. The findings from the present study showed that the I-2 virus coated on the oiled rice is safe, immunogenic and provoked production of protective antibody response following oral vaccination of helmeted guinea fowls.     

Oral vaccination of chickens against Newcastle disease with V4 vaccine delivered on processed rice grains

An international effort (sponsored by the Australian Centre for International Agricultural Research) is being made to develop oral vaccines that will protect village chickens against Newcastle disease. The vaccines being used are derivatives of the avirulent Australian V4 strain that have been selected for enhanced heat resistance. The present study, undertaken in Sri Lanka, used local processed (parboiled) rice as a vehicle for the vaccine. Chickens receiving two doses of vaccine on cooked, parboiled rice were completely protected against contact challenge with the virulent SL 88/1 Sri Lankan strain of Newcastle disease virus Chickens kept in contact with these vaccinated chickens were similarly protected. Lower levels of protection were achieved with vaccine given on uncooked parboiled rice. V4 vaccine administered intranasally also gave complete protection. Serums from vaccinated chickens that survived challenge were tested for haemagglutination-inhibition antibodies, using both vaccine virus and challenge virus as antigens. Titres were higher against vaccine virus.     

Protection of the Reproductive Tract of Young Chicks by Newcastle Disease Virus-induced Haemagglutinationinhibition Antibodies

The present study was conducted to assess the haemagglutination-inhibition (HI) titres required to protect the chicken reproductive tract against direct damage caused by Newcastle disease virus (NDV). Precociously induced oviduct and uterus by oestrogen treatment of young chicks were used to assess the damage or protection against the damage by analysis of ciliostasis or histopathological lesions. Unvaccinated day-old female white leghorn chickens were used as the maternally derived antibody (MDA) group. Chickens were vaccinated with either a live lentogenic vaccine on day 14 of age or, along with it, an inactivated vaccine at day 36 of age, to generate birds with a range of primary or secondary response induced HI antibodies. Birds with different HI antibody levels were challenged with virulent NDV. It was found that a HI antibody titre of 128 and above was protective against direct damage of the reproductive tract, while the 32–64 titre range was protective when derived through secondary vaccination only.     

基于新城疫病毒V蛋白鉴别鸡群感染与免疫的间接ELISA方法的建立

本研究以新城疫病毒(NDV)V蛋白羧基端结构域(Vc)的重组蛋白为包被抗原,建立了用于检测NDV V蛋白抗体的间接ELISA方法,并采用该方法检测了鸡群免疫或接毒后血清中的V蛋白抗体水平。结果显示:两组不同NDV灭活疫苗组在免疫后的3周内检测结果均为阴性;两组灭活疫苗免疫3周后再人工感染NDV强毒的鸡群,攻毒后第7、14和21 d,NDV阳性率分别为60%、80%、70%和50%、80%、70%;两组不同的NDV弱毒疫苗免疫组鸡群,仅在免疫后第21 d阳性率分别为20%和10%。以上结果表明,NDV疫苗免疫组与强毒感染组的V蛋白抗体阳性率存在明显差异,本方法可在群体水平上区分新城疫疫苗免疫与强毒感染鸡群,为NDV血清学诊断和流行病学调查提供了一种新的检测手段。     

Protective immune response of chickens to oral vaccination with thermostable live Fowlpox virus vaccine (strain TPV-1) coated on oiled rice

The objective of the present study was to develop and evaluate a local vaccine (strain TPV-1) against Fowl pox (FP) in chickens. Two separate groups of chickens were vaccinated with FP vaccine through oral (coated on oiled rice) and wing web stab routes, respectively. The results showed that the haemagglutination-inhibition (HI) antibody titres in both vaccinated groups were comparable and significantly higher (P < 0.05) than the control chickens. It was further revealed that 14 days after vaccination HI GMT of ≥2 log₂ was recorded in chickens vaccinated by oral and wing web stab routes whereas 35 days after vaccination the HI antibody titres reached 5.6 log₂ and 6.3 log₂, respectively. Moreover, in both groups the birds showed 100% protection against challenge virus at 35 days after vaccination. The findings from the present study have shown that oral route is equally effective as wing web stab route for vaccination of chickens against FP. However, the oral route can be used in mass vaccination of birds thus avoid catching individual birds for vaccination. It was noteworthy that strain TPV-1 virus could be propagated by a simple allantoic cavity inoculation and harvesting of allantoic fluid where it survived exposure at 57°C for 2 hours. If the oral vaccination technique is optimized it may be used in controlling FP in scavenging and feral chickens. In conclusion, the present study has shown that FP vaccine (strain TPV-1) was safe, thermostable, immunogenic and efficacious in vaccinated chickens.     

鸡新城疫重组鸡痘病毒活疫苗的免疫持续期和加强免疫研究

本研究旨在评价表达新城疫病毒（NDV）血凝素-神经氨酸酶（HN）基因的重组鸡痘病毒（rFPV-12LSHN）活疫苗的免疫持续期和加强免疫对疫苗免疫效力的影响。用rFPV-12LSHN活疫苗免疫14日龄SPF鸡,103PFU/羽,7d即可检测到NDV HI抗体应答,对NDV强毒F48E8株攻毒保护率达100%。一次免疫18周后,对NDV强毒攻击依然提供完全保护。鸡痘病毒（FPV）疫苗免疫4周,再接种rFPV-12LSHN活疫苗,攻毒保护率降低至50%。相反,rFPV-12LSHN免疫4周,随后二次免疫可显著提高对NDV的体液免疫应答水平（P〈0.01）,对NDV强毒攻击的保护率仍然为100%。结果表明,表达NDV HN基因的重组鸡痘病毒（rFPV-12LSHN）活疫苗,能够快速建立坚强免疫力,免疫持续期至少可达18周,rFPV-12LSHN的二次免疫可以提高疫苗的免疫力。