AI Vaccine Research Articles

Analysis of the Ghanaian Public Health Act, AI Regulatory Regimes and Vaccine Manufacturing and Distribution Channels in Ghana

Objective: Analyze Ghana's public health law comprehensiveness, responsiveness, uniformity and accountability regarding complex modern risks at the intersection of infectious disease, medical AI and vaccine equity. Method: Doctrinal legal review (CRuPAC) of the 2012 Public Health Act combined with sociolegal analysis of judicial cases, academic literature and comparative governance on emerging technologies. Results: Gaps exist regarding infectious disease forecasting, transparency duties, decentralized flexibility and technology regulation that constrained pandemic response. Conclusions: Ghana's outdated health law requires modernization to address twenty-first century convergence of biotechnology, data usage and human rights. Recommendations: Parliament should amend legislation to embed oversight, participatory mechanisms and binding duties around accountable and rights-respecting development and deployment of AI tools supporting vaccine delivery. Contributions: Provides novel interdisciplinary framework assessing legal readiness for scientific healthcare priorities. Significance: Analyzes institutional deficiencies and reform options for life-saving technology integrations.

Evaluation of Superficial Well Water on the performance and Immune-response of Broiler Chickens Against Avian Influenza and Newcastle Diseases Vaccination in New Valley Governorate.

A total of 200 unsexed 1-day old broiler chickens (Masr poultry) were used in this study in El-Dakhla City in the New Valley Governorate. They were randomly allocated into two groups of 100 birds in each. Groups were classified according to water source, (G1) received superficial well water (S) and (G2) received filtered water (F), that have been physically and chemically analyzed. The two groups received balanced formulated diet free from any additives and vaccinated with AI (H9) and ND vaccines. Weekly, five chicks were randomly collected and weighted (FI, BWG and FCR were estimated), At (1, 7, 15, 25, 35 days) 5 serum samples were examined for the antibody titers of AI (H9) and ND vaccines using HI test. The results of physicochemical water analyses recorded higher numerical values in superficial well group than filtered group which exceeded the permissible limits. There are significant differences among groups at (p>0.05) for most of the performance and immune parameters. (G2) showed a significant higher response for body weight (BWT), BWT gain (BWG), feed conversion ratio and antibody response to ND and AI (H9) virus vaccine. Our study showed that concentration of heavy metals residues in different tissues of broilers received Superficial well as (Fe, Mn, Pb and CD) recorded higher result as compared with filter group. In conclusion, In El Dakhla City the superficial well water affect negatively on performance and immune parameters of broiler chickens.

Efficacy of the recently registered inactivated Avian Influenza H5 (Re-13 & Re-14) vaccine in commercial broiler chickens compared to that of Re-5 & Re-6+Re-8 AI vaccines against the currently circulating HPAI H5N8 strain in Egypt

Efficacy of the recently registered inactivated Avian Influenza H5 (Re-13 & Re-14) vaccine in commercial broiler chickens compared to that of Re-5 & Re-6+Re-8 AI vaccines against the currently circulating HPAI H5N8 strain in Egypt

Addition of Mycobacterium Cell Wall Fraction as Immunomodulator to Improve the Efficacy of Oil Emulsion-Inactivated Avian Influenza Vaccine in Broiler Chickens

Mycobacterial lipids have strong immunomodulatory effects which can be exploited for vaccine development. In this Study, we associated the injection of Mycobacterium Cell Wall Fraction (MCWF) with vaccination against Avian Influenza H9N2 by using a commercial inactivated oil emulsion vaccine in Broiler chicken and assessed the immune response. High levels of mucosal hemagglutinin inhibitory antibodies were detected in groups immunized with MCWF and AI vaccine, compared to group vaccinated with AI vaccine alone. MCWF induced a longer and an increased local protection in both respiratory and intestinal tracts. Serum levels of antibodies were not significantly different among groups. Cytokines of humoral and cell mediated immunity were also assessed. MCWF influences the balance Th1/Th2, by increasing Th2 cytokines that downregulate the cellular immune response and promote innate immune response, and inducing the Th1/Th2 network. Our results show that MCWF has a potential to be used as adjuvant in AI vaccines by inducing a robust, broad and long lasting protective immune responses in broiler chickens. Keywords: Immunomodulation, Avian Influenza, vaccination, Mycobacterium Cell Wall fraction, Adjuvant. Read more →

A broad spectrum HVT-H5 avian influenza vector vaccine which induces a rapid onset of immunity

Current methods to combat highly pathogenic avian influenza (HPAI) outbreaks in poultry rely on stamping out and preventive culling, which can lead to high economic losses and invoke ethical resistance. Emergency vaccination could be an alternative as vaccination is one of the most efficient and cost-effective measures to protect poultry from HPAI infection, preventing spreading to other poultry and greatly reducing the potential transmission to humans. Current conventional inactivated AI vaccines may be useful for combating AI outbreaks, but do not fulfil all targets of an ideal AI vaccine, including mass applicability and rapid onset of immunity. We aimed to further investigate the potential of Herpesvirus of Turkeys (HVT) as a vector containing a recombinant H5 hemagglutinin of HPAI H5N1. This HVT-H5 vector was analysed in vitro, tested for onset of immunity against AI challenge, breadth of protection, reduction of virus shedding, and induction of both antibody and cellular responses in SPF layers or broiler chicks containing maternal derived antibodies (MDA+). In SPF layers HVT-H5 provided full protection to lethal challenges with 4 antigenically diverse HPAI H5N1 strains from 2 weeks post vaccination (w.p.v.), while in MDA+ birds full protection was provided from 3 w.p.v. to homologous challenge. Also shedding of challenge virus was reduced in both SPF and MDA+ birds. HVT-H5 induced a protective HI titre (≥4) to 11 HPAI H5N1 strains at 3 w.p.v. in 3-week-old SPF layers and to HPAI H5N8 A/ch/Neth/14015531/2014. Besides inducing a protective antibody response HVT-H5 also induced an influenza-specific T cell response. This data demonstrates that HVT-H5 vaccine appears to fulfil many of the criteria for an ideal AI vaccine including early onset of immunity, a broad protection, reduced virus shedding, protection in presence of AI-MDA and could be a useful tool in the combat of AI outbreaks worldwide.

Demand driven livestock extension services: Farmers' participatory assessment in Eastern Haryana

India is the house of the largest livestock population as well as highest milk producing country of the world. But, productivity of the large ruminant, i.e. cattle and buffalo is far below the world standard. Hence, the delivery of livestock extension services is emerging as an important priority area for enhancing and optimizing livestock production and productivity. At present livestock farming in India is at transition phase, i.e. transforming from subsistence to a commercial venture. Therefore, 100 livestock farmers and 60 commercial livestock farmers were randomly selected from the two highly crossbred populated districts of eastern Haryana to understand their demand for livestock extension services particularly livestock extension services other than the routine one. Incomplete Order of Merit Rating as Suggested by Garret was used to assess the degree of importance of the identified demand driven livestock extension services. A total 26 livestock extension services were demanded by the farmers of the eastern Haryana amongst which three services for specialized breeding services, 5 for animal feeding purposes, 7 for livestock production and management 6 for healthcare related and 5 services towards marketing and extension services. Both types of the farmers had a highest demand for conventional livestock extension services like timely AI services, vaccination services and non-conventional extension service like demonstration-cum-training programme on Azolla production and conservation. Livestock farmers were highly interested to grow as an entrepreneur, whereas, commercial livestock farmers were highly interested to strengthen their farm by securing credit accessibility. Hence, Livestock farmers' need on specialized demand driven extension services has been identified along with their degree of importance which may help in policy formulation in future for re-institutionalized public livestock extension services.

Are current avian influenza vaccines a solution for smallholder poultry farmers?

Vaccination against highly pathogenic avian influenza (HPAI) viruses, along with other measures, was successful in eradicating AI in very few countries where the competence of national veterinary services or the geography and bird density have contributed favorably to the outcome. The main constraints to an effective AI vaccination are vaccine composition matching field strains, reliable cold chain and logistics to target all poultry smallholders, constraints related to the availability of sufficient financial and human resources. When not conducted properly, vaccination can also contribute to the emergence of new field viral strains, through genetic drifts of HPAI viruses. While new technologies have improved the possibility to produce high quality vaccines matching field strains, recurrent issues like post-vaccination field surveillance and vaccination coverage continue to limit the relevance of AI vaccination in smallholder settings. A "game-changer" vaccine targeting smallholders should be universal to protect against all field viral strains and reduce significantly, if not totally eliminate, the need for costly post-vaccination surveillance. The ease of administration of this vaccine (eye drop or one single injection) would further contribute to its relevance in the field. These characteristics are considered essential for the product profile of an AI vaccine that can contribute in a meaningful way to the livelihoods of poultry smallholders.

KEMAMPUAN POLISAKARIDA MANNAN SEBAGAI ORAL ADJUVAN VAKSIN AVIAN INFLUENZA PADA AYAM BROILER

Polysaccharides contain mannan (PM) from palm kernel meal (PKM) potential as leader pathogen microorganism and enhancing the immune responses. The objective of the study was to evaluate efficacy of PM as oral adjuvant in increasing AI H5N1 antibody titer and immunoglobulin A (IgA) in serum of broiler thirty chickens age 1 - 6 weeks were divided onto five groups and assigned randomly to five vaccine treatments i.e : un-vaccinated birds (R0A), birds vaccinated with antigen H5N1 + 0 µg PM (R0B), birds vaccinated with antigen H5N1 + 50 µg PM (R1), birds vaccinated with antigen H5N1 + 100 µg PM (R2) and birds vaccinated with antigen H5N1 + 200 µg PM (R3). The results showed the treatment did not reduce broiler body weight (PM is not toxic). AI H5N1 antibody titer increased significantly (P0.05) one week after the first vaccination, serum IgA of broiler also increased significantly (P0.05) two weeks after the second vaccination. R3 treatment (200 μg PM) produce higher HI antibody titer ≤ 5 log2 and serum IgA 1.6 fold higher compared with those of broiler received R0A and R0B. It can be concluded that PM can increase the immune response in broiler chickens and can be used as an adjuvant for inactive AI vaccine.

Efficacy of a Recombinant Turkey Herpesvirus AI (H5) Vaccine in Preventing Transmission of Heterologous Highly Pathogenic H5N8 Clade 2.3.4.4b Challenge Virus in Commercial Broilers and Layer Pullets.

Outbreaks caused by the highly pathogenic avian influenza virus (HPAIV) H5N8 subtype clade 2.3.4.4 were first reported in 2014 in South Korea then spread very rapidly in Asia, to Europe, and for the first time, to North America. Efficacy of a recombinant HVT-AI (H5) vaccine (rHVT-H5) to provide clinical protection as well as to significantly reduce the shedding of an H5N8 challenge virus has already been demonstrated in SPF chickens. The aim of our studies was to test the efficacy of the same rHVT-H5 vaccine in controlling the transmission of a recent Hungarian HPAIV H5N8 challenge virus in commercial chickens. Broilers and layers were vaccinated at day old according to the manufacturer's recommendation and then challenged with a 2017 Hungarian HPAIV H5N8 (2.3.4.4b) isolate at 5 or 7 weeks of age, respectively. Evaluation of clinical protection, reduction of challenge virus shedding, and transmission to vaccinated contact birds was done on the basis of clinical signs/mortality, detection, and quantitation of challenge virus in oronasal and cloacal swabs (regularly between 1 and 14 days postchallenge). Measurement of seroconversion to AIV nucleoprotein was used as an indicator of infection and replication of challenge virus. Our results demonstrated that rHVT-H5 vaccination could prevent the development of clinical disease and suppress shedding very efficiently, resulting in the lack of challenge virus transmission to vaccinated contact chickens, regardless the type of birds. Single immunization with the tested rHVT-H5 vaccine proved to be effective to stop HPAIV H5N8 (2.3.4.4b) transmission within vaccinated poultry population under experimental conditions.

EVALUATION OF RECOMBINANT AVIAN INFLUENZA COMPARED TO INACTIVATED VACCINES TO INDUCE IMMUNE RESPONSE IN CHICKEN

The present Avian Influenza epidemic in Egypt is consider one of the major problems facing the poultry field and caused by circulation of genetically and antigenetically diverse influenza H5N1 viruses. This problem is controlled by applying vaccination. The objective was to determine the AI H5 recombinant vaccines efficacy (rHVT-H5, rFP-AI-H5 (Scotland and Ireland), k rND-AI and k rBuc-AI+ND) against classical and variant field HPAI H5N1 viruses in comparison to the traditionally inactivated whole AI virus vaccines as K R H5N1 / Egy, k H5N2 and k combined AI+ND vaccines. A single dose of the different types of vaccines either recombinant or inactivated whole virus vaccines was administered at different ages of chicken. Eight chicken groups were vaccinated with 8 vaccines and challenged after 4 weeks post vaccination to measure the protection %. Fecal and tracheal swabs were taken after 2 day post challenge to detect viral shedding. It was found that, live rFP-AI-H5 of both Scotland and Ireland strains induced poor clinical protection with high level of virus shedding. While, inactivated rND-AI, live rHVT-H5 and inactivated rBuc-AI+ND vaccines induced high protection rates ranged from 86.7% to 93.3% against both classical and variant HPAI viruses with a decrease or suppression of viruses shedding. In a parallel way, the inactivated whole virus AI vaccines either K R H5N1 / Egy, k H5N2 or k AI+ND induced a protection rates ranged from 85.7% to 100% with a high decrease in virus shedding levels. The data clearly indicate that inactivated whole AI virus and inactivated recombinant vaccines confers high levels of clinical protection with suppression in viral shedding compared to that of live recombinant vaccines except rHVT-H5 vaccine which induce a great level of protection and decrease in viral shedding in SPF chicken.

HISTORY OF HIGHLY PATHOGENIC AVIAN INFLUENZA ERADICATION IN RUSSIAN FEDERATION IN 2016–2017

Epidemic patterns of highly pathogenic avian influenza А/Н5N8 spread in the Russian Federation are demonstrated, history of the disease outbreak eradication in domestic poultry is described, basic reasons of the dangerous virus introduction on the commercial farms are analyzed and issues of the outbreak containment are highlighted. Specific properties of H5N8 disease progression and clinical manifestation are demonstrated against H5N1 disease. Data of epidemic investigations of the virus introduction to the closed-type farms are integrated. Basic attention is given to the destruction of poultry died and stamped out during implementation of anti-epidemic measures, and potential alternative ways of biological waste destruction are demonstrated. Principal risks of introduction of emerging influenza virus subtypes into the Russian Federation are determined. Further spread of avian influenza over the Russian territory is expected due to the current epidemic situation, the virus persistence in the vectors, maintenance of its viability in the environment and seasonal migrations of the wild birds. Major threat of the agent introduction comes from the neighbouring East Asia and Far East countries (China, Japan, Korea). Herewith, introduction of potentially zoonotic viruses is also possible. Risk of the virus introduction from the European countries, Near East countries and Central Asia cannot be excluded. For now, drastic measures still remain the only tool for the disease control and the strategy of limited targeted AI vaccination in the backyards minimizes the virus introduction to the commercial farms located in the risk zones.

Efficacy of Two Commercial Inactivated H5 Avian Influenza Vaccines Against Circulating HPAI Subtype H5N8 in Quails, 2018

To investigate cross-protective efficacy of commercial inactivated H5 avian influenza vaccines against recent HPAI H5N8 virus in quails. We evaluate the efficacy of two inactivated commercial H5 AI vaccine (imported H5N1 vaccine containing (Re-6 strain) and local H5N1 vaccine), using susceptible quails at one week age. The selection of these bird back to its a specific nature which characterized by presence of two types of avian influenza receptors giving a great chance for recombination of the different types of AIV emerging new mutant viruses can threat human health and poultry industry. Susceptible quails used for potency assay inoculated by one field dose and booster dose at 3 week post vaccination from each vaccine. Blood samples are collected weekly from all vaccinated groups and AI, HI antibodies are measured individuals of the collected sera by HI test using homologous H5N1 and heterologous H5N8 AI antigens containing 4 HA units. Vaccinated quails by one dose and booster dose of vaccine were challenged by 100 LD50 HPAI subtype H5N8 intranasally after 2, 4 and 8 weeks post vaccination, and 4 weeks post boostering, respectively. It was found HI antibody titer in sera of quails vaccinated by one or two doses of imported H5N1 AI vaccine containing RE-6 strain elicited higher immune response than local commercial vaccine when examined against homologous H5N1AI antigen, but two vaccines exhibited antibody titer not optimal against heterologous H5N8AI antigens. A challenge test with local H5N8 highly pathogenic influenza virus indicated unsatisfactory protection% for all groups of vaccinated quails.

Isolat Bakteri Asam Laktat Sebagai Probiotik dengan Vaksinasi AI dan ND dalam Pembentukan Titer Antibodi Dan Bobot Badan Ayam Jantan Tipe Medium

Isolates of Lactic Acid Bacteria isolates assembled into a mixture of LAB as probiotics . LAB probiotic drops introduced through the mouth with the aim of suppressing pathogens and is expected to improve the health status of rooster type of medium . Isolates in the digestive tract will undergo adaptation by temperature , acidity and pH changes in the gut . The health status of the chicken can be expressed as growth to form the body weight , and the growth of LAB . In addition , AI and ND vaccination in healthy chickens conditions will produce antibodies to both . The success of vaccination can be evaluated from the results of the formation of chicken blood serum titre of research . Analysis of descriptive data on the dynamics of the growth of LAB , the formation of antibody titer and body weight gain 24-31 day old chickens . Based on the results of this study revealed that isolates of LAB can be used simultaneously in bercoccidiostat feed . LAB isolates may develop in the digestive tract rooster medium type as probiotics. The dynamics of the growth of a population produces a mixture of isolates of LAB isolates (mixture of B1, B3, B4, B5 as probiotics) in the highest reaches of the ilium and jejunum 14.00 x 10-6 13.5 x 10-6 CFU/ml. Test isolates viability of probiotic candidates in all isolates produced distilled water medium can live up to 72 hours of incubation . In addition, there is a synergy results in the formation of antibody titers ND uniform T3 treatment. T3 treatment is given probiotics 2x chicken every week for 3 weeks . In AI vaccination resulted in antibody titers are not uniform. Body weight gain reached the age of 24-31 days in a row 75.83 g, 76.54 g, 81.58 g, 87.04 g. Weight age of 31 days the average value obtained successively from the highest 329.16 g, 328.54 g, 325.54 g and 324.08 g lowest . Keywords; isolates LAB, probiotics, antibody titers, rooster layer medium type.

Heterologous prime-boost immunization of Newcastle disease virus vectored vaccines protected broiler chickens against highly pathogenic avian influenza and Newcastle disease viruses.

Avian Influenza virus (AIV) is an important pathogen for both human and animal health. There is a great need to develop a safe and effective vaccine for AI infections in the field. Live-attenuated Newcastle disease virus (NDV) vectored AI vaccines have shown to be effective, but preexisting antibodies to the vaccine vector can affect the protective efficacy of the vaccine in the field. To improve the efficacy of AI vaccine, we generated a novel vectored vaccine by using a chimeric NDV vector that is serologically distant from NDV. In this study, the protective efficacy of our vaccines was evaluated by using H5N1 highly pathogenic avian influenza virus (HPAIV) strain A/Vietnam/1203/2004, a prototype strain for vaccine development. The vaccine viruses were three chimeric NDVs expressing the hemagglutinin (HA) protein in combination with the neuraminidase (NA) protein, matrix 1 protein, or nonstructural 1 protein. Comparison of their protective efficacy between a single and prime-boost immunizations indicated that prime immunization of 1-day-old SPF chicks with our vaccine viruses followed by boosting with the conventional NDV vector strain LaSota expressing the HA protein provided complete protection of chickens against mortality, clinical signs and virus shedding. Further verification of our heterologous prime-boost immunization using commercial broiler chickens suggested that a sequential immunization of chickens with chimeric NDV vector expressing the HA and NA proteins following the boost with NDV vector expressing the HA protein can be a promising strategy for the field vaccination against HPAIVs and against highly virulent NDVs.

Homologous and heterologous antigenic matched vaccines containing different H5 hemagglutinins provide variable protection of chickens from the 2014 U.S. H5N8 and H5N2 clade 2.3.4.4 highly pathogenic avian influenza viruses.

From December 2014 to June 2015, a novel H5 Eurasian A/goose/Guangdong (Gs/GD) lineage clade 2.3.4.4 high pathogenicity avian influenza (HPAI) virus caused the largest animal health emergency in US history resulting in mortality or culling of greater than 48 million poultry. The outbreak renewed interest in developing intervention strategies, including vaccines, for these newly emergent HPAI viruses. In these studies, several existing H5 vaccines or vaccine seed strains with varying genetic relatedness (85-100%) to the 2.3.4.4 HPAI viruses were evaluated for protection in poultry. Chickens received a single dose of either an inactivated whole H5 AI vaccine, or a recombinant fowl poxvirus or turkey herpesvirus-vectored vaccines with H5 AI hemagglutinin gene inserts followed by challenge with either a U.S. wild bird H5N8 (A/gyrfalcon/Washington/40188-6/2014) or H5N2 (A/northern pintail/Washington/40964/2014) clade 2.3.4.4 isolate. Results indicate that most inactivated H5 vaccines provided 100% protection from lethal effects of H5N8 or H5N2 challenge. In contrast, the recombinant live vectored vaccines only provided partial protection which ranged from 40 to 70%. Inactivated vaccine groups, in general, had lower number of birds shedding virus and at lower virus titers then the recombinant vaccine groups. Interestingly, prechallenge antibody titers using the HPAI challenge viruses as antigen in heterologous vaccine groups were typically low (≤2 log2), yet the majority of these birds survived challenge. Taken together, these studies suggest that existing vaccines when used in a single immunization strategy may not provide adequate protection in poultry against the 2.3.4.4 HPAI viruses. Updating the H5 hemagglutinin to be genetically closer to the outbreak virus and/or using a prime-boost strategy may be necessary for optimal protection.

The response of mute swans (Cygnus olor, Gm. 1789) to vaccination against avian influenza with an inactivated H5N2 vaccine.

BackgroundRecent epidemics of highly pathogenic avian influenza (HPAI) produced an unprecedented number of cases in mute swans (Cygnus olor) in European countries, which indicates that these birds are very sensitive to the H5N1 virus. The HPAI outbreaks stirred a debate on the controversial stamping-out policy in populations of protected bird species. After preventive vaccination had been approved in the European Union, several countries have introduced vaccination schemes to protect poultry, captive wild birds or exotic birds in zoos against HPAI. The aim of this study was to investigate the immune response of wild mute swans to immunization with an inactivated AI H5N2 vaccine approved for use in poultry. The serological responses of mute swans were assessed by comparison with racing pigeons (Columba livia), a species which is characterized by different susceptibility to infection with the H5N1 HPAI virus and plays a questionable role in the ecology of influenza (H5N1) viruses.ResultsSwans were vaccinated once or twice at an interval of 4 weeks. The humoral immune response was evaluated by hemagglutination inhibition (HI) and NP-ELISA. The lymphocyte blast transformation test was used to determine the cell-mediated immune response. Higher values of the geometric mean titer (GMT) and 100 % seroconversion (HI ≥32) were noted in double vaccinated swans (1448.2) than in single vaccinated swans (128.0) or in double vaccinated pigeons (215.3). Significant differences in HI titers were observed between swans and pigeons, but no variations in ELISA scores were noted after the booster dose. Immunization of swans had no effect on the proliferative activity of lymphocytes.ConclusionsThe inactivated H5N2 vaccine was safe and immunogenic for mute swans and pigeons. Vaccination may have practical implications for swans kept in zoos, wildlife parks or rehabilitation centers. However, challenge studies are needed to prove the efficacy of the H5N2 AI vaccine.

Protective efficacy of a prime-boost protocol using H5-DNA plasmid as prime and inactivated H5N2 vaccine as the booster against the Egyptian avian influenza challenge virus.

In this study, a recombinant DNA plasmid was constructed, encoding for HA1 of a selected Egyptian H5N1 virus (isolated during the 2012 outbreaks). In the immunization and challenge experiments, SPF chickens received 1 or 2 doses of H5-DNA plasmid prime, and boosted with the inactivated H5N2 vaccine. Haemagglutination inhibition (HI) titers, protection levels, and the magnitude of virus shedding were compared to that of the chickens that received either DNA plasmid or inactivated H5N2 vaccine alone. H5N1 virus A/chicken/Egypt/128s/2012 (H5N1) highly pathogenic avian influenza (HPAI) clade 2.2.1/C was used for the challenge. Chickens immunized with 1 or 2 doses of H5-DNA vaccine failed to overcome the challenge with 0% and 10% protection, respectively. Quantitative real-time reverse transcription-PCR revealed virus shedding of 2.2 x 104 PCR copies/ml 3 days post challenge (dpc) in the only surviving bird from the group that received 2 doses of plasmid. However, chickens immunized with 1 or 2 doses of H5-DNA plasmid as prime and inactivated H5N2 vaccine as booster, showed 80% protection after challenge, with a viral shedding of 1.2 x 104 PCR copies/ml (1 dose) and 1.6 x 104 PCR copies/ml (2 doses) 3 dpc. The surviving birds in both groups did not shed the virus at 5 and 7 dpc. In H5N2-vaccinated chickens, protection levels were 70% with relatively high virus shedding (1.8 x 104 PCR copies/ml) 3 dpc. HI titers were protective to the surviving chickens. This study reports the efficacy of H5-DNA plasmid to augment reduction in viral shedding and to provide better protection when applied in a prime-boost program with the inactivated AI vaccine.

Consequence of Cryptosporidiosis on the immune response of vaccinated broiler chickens against Newcastle disease and/or avian influenza.

The consequence of cryptosporidiosis on the immune response of vaccinated chickens against Newcastle disease and/or avian influenza was studied by using 240, 1 day old, male, white Hy-Line chicks and divided into 8 groups and subgroups. Each group or subgroup was consisting of 30 chicks (15 × 2 replicates). The first and second groups were kept as unvaccinated control, G1uninfected and G2 infected. G3, G4 and G5 contained 2 subgroups A&B (G3A, G3B, G4A, G4B, G5A and G5B). Chicks of subgroup A were vaccinated only while chicks of subgroup B were infected and vaccinated. These chicks were orally inoculated with 5 × 10(5) oocysts of Cryptosporidium baileyi (C. baileyi) at 2 days of age. Chickens were vaccinated intraocular with live Newcastle disease (ND) vaccine (Hitchner on day 7th and LaSota on day 17th of chicken life) (G3) or vaccinated by subcutaneous route with Volvac®- H5N2- AI vaccine on day 10 of chicken life (G4). Last group (G5) was infected similarly and vaccinated with ND and AI vaccines with the same day, dose and route of vaccination for each one. Random blood samples were collected for 3 weeks post-vaccination for investigation of humoral immune response against Newcastle and/or avian influenza vaccines by the haemagglutination inhibition (HI) test. The results showed that H5N2 vaccine at day 10 of chicken life is effective in chickens indicated by the geometric mean of HI titer against AI virus. The findings of this study showed that the infection with Cryptosporidia in the broiler chicken has a depressive effect on the immune status of the birds vaccinated against ND and/or AI vaccination. Moreover, the obtained protection rates against challenge with virulent ND virus observed to be parallel to the results of HI- test. Also, by using 2 different antigens (one commercial and field prepared antigen) to avian influenza virus, lower Geometric mean (GM) HI titer were appeared in infected and vaccinated group than vaccinated group only. A study of the relative lymphoid organs weight such as bursa of Fabricius from the experimental chicks indicated that those organs were comparable between the groups infected-vaccinated and vaccinated only. Non significant variations in final live weight between uninfected control and infected groups were indicated. Also, H5N2-AI vaccination at 10 days old did not affect the final live weight. ND and/or AI Vaccination could not be a substitute to application of good hygienic measures and fecal examination of the birds especially for protozoal diseases such as cryptosporidiosis. It could be concluded that cryptosporidiosis could be one cause of ND and/or AI vaccination failure in poultry farms.

Immunogenecity D Efficacy of Locally Prepared Montanide-oil Based H5N2 AI Vaccine Containing Flagellin As Immune Enhancer

Immunogenecity D Efficacy of Locally Prepared Montanide-oil Based H5N2 AI Vaccine Containing Flagellin As Immune Enhancer

Success Factors for Avian Influenza Vaccine Use in Poultry and Potential Impact at the Wild Bird–Agricultural Interface

Thirty-two epizootics of high pathogenicity avian influenza (HPAI) have been reported in poultry and other birds since 1959. The ongoing H5N1 HPAI epizootic that began in 1996 has also spilled over to infect wild birds. Traditional stamping-out programs in poultry have resulted in eradication of most HPAI epizootics. However, vaccination of poultry was added as a control tool in 1995 and has been used during five epizootics. Over 113 billion doses of AI vaccine have been used in poultry from 2002 to 2010 as oil-emulsified, inactivated whole AIV vaccines (95.5%) and live vectored vaccines (4.5%). Over 99% of the vaccine has been used in the four H5N1 HPAI enzootic countries: China including Hong Kong (91%), Egypt (4.7%), Indonesia (2.3%), and Vietnam (1.4%) where vaccination programs have been nationwide and routine to all poultry. Ten other countries used vaccine in poultry in a focused, risk-based manner but this accounted for less than 1% of the vaccine used. Most vaccine "failures" have resulted from problems in the vaccination process; i.e., failure to adequately administer the vaccine to at-risk poultry resulting in lack of population immunity, while fewer failures have resulted from antigenic drift of field viruses away from the vaccine viruses. It is currently not feasible to vaccinate wild birds against H5N1 HPAI, but naturally occurring infections with H5 low pathogenicity avian influenza viruses may generate cross-protective immunity against H5N1 HPAI. The most feasible method to prevent and control H5N1 HPAI in wild birds is through control of the disease in poultry with use of vaccine to reduce environmental burden of H5N1 HPAIV, and eventual eradication of the virus in domestic poultry, especially in domestic ducks which are raised in enzootic countries on range or in other outdoor systems having contact with wild aquatic and periurban terrestrial birds.