AI Vaccine efficacy study
- From: " Jill" <newsNOSPAM@xxxxxxxxxxxxxxx>
- Date: Fri, 17 Feb 2006 19:42:19 -0000
http://www.avian-influenza.com/Control/efficacy_study.asp
Efficacy of Avian influenza vaccines, H5 subtype
Summary of data
Introduction
Since 2002, Hong Kong has vaccinated successfully against H5N1 outbreaks
with an inactivated H5N2 vaccine (Nobilis Influenza H5, Intervet). After the
start of new outbreaks of Avian Influenza, sub-type H5N1, in Asia in 2003,
it was questioned whether the present H5N2 vaccines offered protection
against the 2003 H5N1 field isolate.
In this study 2 H5N2 vaccines (Nobilis Influenza H5, origin Mexico and
Nobilis H5N2, origin Spain, both vaccines are from Intervet) were tested in
a challenge experiment.
The study was carried out by Dr. David E. Swayne, DVM, PhD, Laboratory
Director Southeast Poultry Research Laboratory, USDA/ARS, Athens, Georgia.
This summary is made by Intervet and based on the experimental data,
received from Southeast Poultry Research Laboratory. The results of this
study will be submitted for publication in a peer-reviewed scientific
journal later in 2004.
Materials
Vaccines
Inactivated vaccines, adjuvant water in oil emulsion.
Nobilis Influenza H5N2, origin Mexico, produced by Intervet.
Nobilis Influenza H5N2, origin Spain, produced by Intervet.
Test animals
SPF White Leghorn chickens, age at vaccination 3 weeks of age.
Challenge
Intranasal challenge with 106.0EID50 at 3 weeks post vaccination (H5N1
isolate from the AI outbreak in Asia in 2003).
Groups
Group 1: No vaccination against AI, vaccination against ND.
Group 2: Nobilis Influenza H5, batch MM 03424, expiry 12/2005 (500ml, 1000
dose), 0.5 ml per dose, administration subcutaneous.
Group 3: Nobilis Influenza H5N2, batch IP 0305036, expiry 12/2004 (100ml,
200 dose), 0.5 ml per dose, administration subcutaneous.
Results
Morbidity:
In the control group (Group 1) all chickens showed clinical signs of high
pathogenic Avian Influenza virus infection.
In vaccinate Group 2, none of the chickens showed clinical signs.
In vaccinate Group 3, only 1 chicken showed clinical disease. This chicken
did not have a pre-challenge antibody titre, which might indicate that it
was a non-responder or possibly was missed during vaccination.
Mortality:
In the control group (Group 1) all chickens died of Avian Influenza.
In vaccinate Group 2 none of the chickens died.
In vaccinate Group 3 only 1 chicken died. This chicken did not have a
pre-challenge antibody titre, which might indicate that it was a
non-responder or possibly was missed during vaccination.
Serology:
None of the chickens in the control group (non-vaccinated against AI, Group
1) had pre-challenge antibody titres in the AGP and HI test.
In vaccinate Group 2 all chickens had pre-challenge titres in the AGP and in
the HI test (average 1:128).
In vaccinate Group 3, 9 out of 10 chickens had pre-challenge titres in the
AGP and in the HI test (average 1:120).
Re-isolation of challenge virus on day 2 post-challenge:
In the control group (Group 1) all chickens (10 of 10)excreted the challenge
virus The average virus titre was 106.16EID50 /ml in oropharyngeal swab
media and 105.82EID50 /ml in cloacal swab media.
In vaccinate Group 2, 5 out of 10 chickens excreted virus from the
oropharynx with an average titre of 101.23EID50 /ml of oropharyngeal swab
media and 3 of 10 chickens excreted virus from cloaca with an average titer
of 101.0EID50 /ml of cloacal swab media.
In vaccinate Group 3, 6 out of 10 chickens excreted virus from the
oropharynx with an average titre of 101.78EID50 /ml of oropharyngeal swab
media and 3 of 10 chickens excreted virus from cloaca with an average titre
of 101.53EID50 /ml of cloacal swab media.
Summary of re-isolation rates.
Virus isolation (2 DPC) log10EID50 titre per ml
oralcloacal
Animals
excretingAverage in
excreting birdsAnimals
excretingAverage in
excreting birds
Group 1, controls10/106.1610/105.82
Group 2, vaccinated5/101.233/101.00
Group 3, vaccinated6/101.783/101.53
Conclusions
The experiment showed that both vaccines induced complete protection against
clinical disease and mortality with the exception of 1 bird in Group 3,
which did not have pre-challenge antibody titres.
The experiment showed that after challenge of non-vaccinated birds all birds
excreted virus at 2 days after challenge at very high virus titres.
After challenge of vaccinated birds virus excretion was prevented in the
majority of birds. In the birds, which excreted virus, the average virus
titres were between 10.000 and 100.000 times less than in the non-vaccinated
birds.
In an outbreak of Avian Influenza, reduction of virus circulation is a very
important factor in preventing spread of Avian Influenza to other birds and
to people. Reduction of virus excretion significantly reduces the chance
that an infected farm will infect another farm.
This experiment shows that vaccination with the tested vaccines can have an
important contribution to the control of Avian Influenza outbreaks.
--
regards
Jill Bowis
Pure bred utility chickens and ducks
Housing; Equipment, Books, Videos, Gifts
Herbaceous; Herb and Alpine nursery
Working Holidays in Scotland
http://www.kintaline.co.uk
.
- Follow-Ups:
- Re: AI Vaccine efficacy study
- From: Jim Webster
- Re: AI Vaccine efficacy study
- Prev by Date: Re: Bird Flu - Egypt
- Next by Date: Re: Bird Flu - England
- Previous by thread: Bird Flu Azerbaijan
- Next by thread: Re: AI Vaccine efficacy study
- Index(es):
Relevant Pages
|
