Evaluation of avian influenza vaccines on commercial layer

chicks

M.M. Amer, Sherein, S.abdelgayed and Abeer, A. Abd El-Baky

Introduction

• Avian influenza Avian influenza (AI) (AI) is one of the highly is one of the highly contagious Office of International contagious Office of International Epizootics Epizootics (OIE) (OIE) list list “A”“A” diseases. The diseases. The disease is also called disease is also called “fowl plague” “fowl plague” due due to its high mortality in chicken. to its high mortality in chicken.

• On rare occasions, AI viruses have On rare occasions, AI viruses have exhibited interspecies transmissibility exhibited interspecies transmissibility to human. to human.

Introduction

• Different levels of control measures have Different levels of control measures have

been implemented to control the been implemented to control the

outbreaks that included condemnation of outbreaks that included condemnation of

infected farms, strict bio-security and infected farms, strict bio-security and

vaccination of commercial chickens vaccination of commercial chickens

• Vaccination as a supportive tool in AI Vaccination as a supportive tool in AI

virus control strategies was implemented virus control strategies was implemented

to limit spread of H5N1 and to reduce the to limit spread of H5N1 and to reduce the

losses. losses.

Introduction

• Different types of vaccines are Different types of vaccines are

already in use that decrease already in use that decrease

shedding of virus, morbidity, shedding of virus, morbidity,

mortality and transmissibilitymortality and transmissibility

• through increasing resistance to through increasing resistance to

infection and reducing field virus infection and reducing field virus

replication.replication.

Introduction

• Evaluation of different types of AI Evaluation of different types of AI

vaccines used in Egypt may provide vaccines used in Egypt may provide

effective vaccination strategy.effective vaccination strategy.

• Moreover, Moreover, the combinant vaccine of the combinant vaccine of

avian influenza and Newcastle avian influenza and Newcastle

disease (AI&ND) was recently disease (AI&ND) was recently

recommended and commercialized recommended and commercialized

for more protection against AI.for more protection against AI.

Purpose of the study

The purpose of the current study was to

•Evaluate inactivated monovalent (H5N1) and Evaluate inactivated monovalent (H5N1) and

bivalent (H5N1&ND) AI vaccines bivalent (H5N1&ND) AI vaccines

•through its immune response, through its immune response,

clinicopathological and histopathological clinicopathological and histopathological

effects on vaccinated layer chicks.effects on vaccinated layer chicks.

Materials and MethodsMaterials and MethodsExperimental designExperimental design

Materials and MethodsMaterials and Methods Sampling Sampling

Materials and MethodsMaterials and Methods Sampling Sampling

Results and Discussion

Results and Discussion

Results and Discussion

Results and Discussion3- Clinicopathological Findings Erythrogram Erythrogram mean values (packed cell

volume (PCV %), hemoglobin concentration (Hb),

erythrocytes count (RBCs), mean corpuscular

volume (MCV) and mean corpuscular hemoglobin

concentration (MCHC)) of different experimental

groups, in comparison to those of control

group (A) showed, insignificant changes in

vaccinated groups B and C.

Results and Discussion3- Clinicopathological Findings Leukogram Mean values of leukogram [total leukocyte

count (TLC), neutrophil, lymphocyte and

monocyte counts] of different experimental

groups showed significant leukocytosis due

to significant lymphocytosis started from the

2nd week in all experimental groups.

Results and Discussion3- Clinicopathological Findings LeukogramThis lymphocytosis was a result of

immunostimulatory effect of vaccination.

Lymphocytosis which observed in group C

(vaccinated with bivalent AI vaccine) was higher than those in group B (vaccinated with monovalent AI vaccine)

The avian influenza vaccines have been shown to induce antigen specific lymphocyte responses that may explain the observed lymphocytosis

Results and Discussion3- Clinicopathological Findings Serum Biochemical Evaluation Compared to control group, protein profile

results showed no significant changes were

observed in albumin concentration.

while, significant hyperproteinemia due to

hyperglobulinemia with significant decrease in

A/G ratio started from 2nd week in all experimental

groups was recorded.

Results and Discussion3- Clinicopathological Findings Serum Biochemical Evaluation This hyperglobulinemia may be attributed to

the high levels of gamma globulins

(immunoglobulin especially IgG and IgA)

associated with chicken vaccination by AI vaccine

Hyperglobulinemia which observed in group C

(vaccinated with bivalent AI vaccine)

was higher than those in group B

(vaccinated with monovalent AI vaccine).

Results and Discussion3- Clinicopathological Findings Serum Biochemical EvaluationActivities of serum liver enzymes (AST, ALT and ALP)

and concentrations of blood glucose, serum creatinine and uric acid showed; insignificant changes throughout the experiment in all groups.

This revealed that the vaccination with both

inactivated monovalent and bivalent AI vaccines

did not affect liver and kidney functions.

Results and Discussion

4- Histopathological Findings

Bursa of Fabricious

1st week

All groups were normal

Bursa of fabricious from all groups at 1week showing apparently normal lymphoid Follicles (H&E X 200).

Results and Discussion

4- Histopathological Findings Bursa of Fabricious

2nd & 3rd weeksGroups A & C were normal.

Group B revealed interfollicular

congestion

Bursa of fabricious from group B at 2nd & 3rd weeks showing interfollicular congestion (H&E X 200).

Results and Discussion4- Histopathological Findings

Bursa of Fabricious

4th & 5th weeksGroup A was normal.

Group B revealed interfollicular edema at 4th week and normal follicles at 5th week.

Group C revealed lymphocytic hyperplasia and lymphoblastic activation at4th&5thweeks

Bursa of fabricious from group B at 4th week showing interfollicular edema (H&E X 200).

Bursa of fabricious from group C at 4th & 5th week showing lymphocytic hyperplasia and lymphoblastic activation

(H&E X 200).

Results and Discussion

4- Histopathological Findings Thymus

1st & 2nd weeks

All groups were normal

Thymus from all groups at 1st & 2nd weeks showing apparently normal cortex and medulla (H&E X 200).

Results and Discussion

4- Histopathological Findings Thymus

3rd week

Groups A & C were normal

Group B showed congested medulla

Thymus from group B at 3rd week showing congested medulla (H&E X 200).

Results and Discussion

4- Histopathological Findings Thymus

4th & 5th weeks

Groups A & B were normal

Group C showed slight lymphocytic

hyperplasia

Thymus from group C at 4th & 5th weeks showing revealed slight lymphocytic hyperplasia

(H&E X 200).

Results and Discussion

4- Histopathological Findings Spleen

1st & 2nd weeks

All groups were normal

Spleen from all groups at 1st & 2nd weeks showing apparently normal lymphoid follicles (H&E X 200).

Results and Discussion

4- Histopathological Findings Spleen

3rd & 4th weeksgroups A & C were normal

Group B showed slight lymphocytic

depletion

Spleen from group B at 3rd & 4th weeks showing slight lymphocytic depletion

(H&E X 200).

Results and Discussion

4- Histopathological Findings Spleen

5th week

Group A & B were normal

Group C showed lymphoblastic activation

Spleen from group C at 5th week showing lymphoblastic activation (H&E X 200).

From the present study, it is concluded that,

Bivalent (H5N1&ND)AI vaccine has immunostimulatory effect higher than monovalent (H5N1)AI vaccine.

which reflected on increasing the immune response of its vaccinated chicken against AI virus.

which manifested by its higher globulins concentration and higher mean (HI) antibody titers of chicken against avian influenza virus (AIV) and confirmed histopathologically by the observed hyperplasia of the lymphoid organs.

Conclusion