Evaluation of Immune Responses and Histopathological Effects against Gamma Irradiated Avian Influenza (Sub type H9N2) Vaccine on Broiler Chicken

Abstract Vaccination is a good strategy for the prevention of avian influenza virus. In this research Gamma Irradiated Avian Influenza (Sub type H9N2) Vaccine (GAIV) was prepared by 30 kGy irradiation and used for vaccination of broiler chickens. The purpose was a comparison of immune responses in the two routes of administration for the GAIV vaccine; intranasal and subcutaneously, use of Montanide ISA70 and Trehalose accompanied with irradiated vaccine and compare with formalin vaccine. The Influenza Virus A/Chicken/IRN/Ghazvin/2001/H9N2 was irradiated and used for vaccine formulation, and formalin inactivated AIV was used as conventional vaccine. Chickens were vaccinated by GAIV with and without Trehalose, GAIV and formalin vaccines with ISA70, two routes of administration were intranasal and subcutaneously. All the vaccinated chickens showed a significant increase in antibody titration. The most significant increase of antibody titration was in irradiated vaccine plus Trehalose groups intranasal and subcutaneously. After the first and second intranasal vaccination, the amount of IFN-gamma increased in the irradiated vaccine plus Trehalose group compared to other groups. However, most of the vaccinated groups did not show any significant increase of IFN-α concentration. Histopathological examination revealed lymphocyte infiltration (++), foci dispersed of hemorrhage and edema in intranasal vaccination groups and in addition to these, thickening of alveolar septa was observed in the injection groups. GAIV vaccine can be a good candidate for vaccine preparation, and Trehalose as a stabilizer protects viral antigenic proteins, also makes more absorbance of antigen by the inhalation route. In vaccinated chickens the ulcers in injected vaccines were lower than intranasal vaccines.

Assessment of the safety and efficacy of low pathogenic avian influenza (H9N2) virus in inactivated oil emulsion vaccine in laying hens

In Korea, several outbreaks of low pathogenic AI (H9N2) viral infections leading to decreased egg production and increased mortality have been reported on commercial farms since 1996, resulting in severe economic losses. To control the H9N2 LPAI endemic, the Korea Veterinary Authority has permitted the use of the inactivated H9N2 LPAI vaccine since 2007. In this study, we developed a killed vaccine using a low pathogenic H9N2 AI virus (A/chicken/Korea/ADL0401) and conducted safety and efficacy tests in commercial layer farms while focusing on analysis of factors that cause losses to farms, including egg production rate, egg abnormality, and feed efficiency. The egg production rate of the control group declined dramatically 5 days after the challenge. There were no changes in feed consumption of all three groups before the challenge, but rates of the control declined afterward. Clinical signs in the vaccinated groups were similar, and a slight decline in feed consumption was observed after challenge; however, this returned to normal more rapidly than the control group and commercial layers. Overall, the results of this study indicate that the safety and efficacy of the vaccine are adequate to provide protection against the AI field infection (H9N2) epidemic in Korea.

An inactivated vaccine to control the current H9N2 low pathogenic avian influenza in Korea

The H9N2 subtype low pathogenic avian influenza is one of the most prevalent avian diseases worldwide, and was first documented in 1996 in Korea. This disease caused serious economic loss in Korea's poultry industry. In order to develop an oil-based inactivated vaccine, a virus that had been isolated in 2001 (A/chicken/Korea/01310/ 2001) was selected based on its pathogenic, antigenic, and genetic properties. However, in animal experiments, the efficacy of the vaccine was found to be very low without concentration of the antigen (2(7) to 2(10) hemagglutinin unit). In order to overcome the low productivity, we passaged the vaccine candidate virus to chicken eggs. After the 20th passage, the virus was approximately ten times more productive compared with the parent virus. For the most part, the passaged virus maintained the hemagglutinin cleavage site amino acid motif (PATSGR/GLF) and had only three amino acid changes (T133N, V216G, E439D, H3 numbering) in the hemagglutinin molecule, as well as 18 amino acid deletions (55-72) and one amino acid change (E54D) in the NA stalk region. The amino acid changes did not significantly affect the antigenicity of the vaccine virus when tested by hemagglutination inhibition assay. Though not complete, the vaccine produced after the 20th passage of the virus (01310 CE20) showed good protection against a homologous and recent Korean isolate (A/chicken/Korea/Q30/2004) in specific pathogen- free chickens. The vaccine developed in this study would be helpful for controlling the H9N2 LPAI in Korea.

Isolation and seroprevalence of avian influenzavirus [H9N2] at Islamabad/Rawalpindi

The aim of this study was to isolate and evaluate the seroprevalence of avian influenza virus [AIV] infection in chicken in Pakistan with special reference to its serotype/H9N2. Laboratory based prospective. This study was carried out at department of Biological Sciences, Quaid-e-Azam University Islamabad and National Agricultural Research Centre Islamabad Pakistan from 2000 to 2001. The human virological aspects were dealt by AF Institute of Pathology, Rawalpindi. The chicken flocks studied belonged to different poultry farms located at Islamabad/Rawalpindi area. For the isolation of avian influenza virus, lungs and trachea specimens were processed to prepare virus inoculum and inoculated in 9-day old embryonated eggs via allantoic route. For identification of virus, haemagglutination test and immunofluorescent antibody test [IFA] were used. Serological analysis was done by Agar Gel Precipitation Test [AGPT], Haemagglutination [HA] and Haemagglutination inhibition test [HI]. This study was divided into two parts; firstly the sera of chicken with history of respiratory tract infection were tested for the presence of antibodies against H9N2 virus. Such chicken were found to have seroconverted against H9N2. Secondly, it was aimed to isolate virus from kidneys, lungs and trachea of infected birds by growing virus in 9 days old chick embryos. Out of 40 clinical samples, 9 isolates of AIV were recovered and typed serologically as serotype H9N2. In this scenario, the presence of H9N2 in poultry in the country poses a continuous threat for the emergence of more pathogenic strains of human influenza virus. For this purpose there is a constant need to carry out surveillance for influenza viruses both in birds and humans in the country