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The Occurrence, Diagnosis and Control of Variant Infectious Bronchitis (a coronavirus) in Asia
1. Dr. Rafael Monleon, DVM, MSpVM, ACPV, PAS
Regional Veterinarian (Asia)
Poultry Health Conference
14-15 May 2012, Bangkok (Thailand)
The Occurrence, Diagnosis and
Control of Variant Infectious
Bronchitis in Asia
2. Objectives
• Infectious bronchitis virus (IBV) and
Infectious bronchitis virus variants (IBVv)
• Distribution and prevalence
• Disease manifestations
• Diagnostics and Monitoring
• Current methods to control IBV
3. Current Issue
• From mid-2000s one of the biggest disease
problems in Asia
– Breeders and Broilers
• Massive egg production losses and mortality
• Sometimes hard to recognize as it is mixed with
other respiratory infections
– Often blame problems on ND/AI/APV/Mycoplasma
– Poor diagnosis facilities across the regions
• Vaccination with classic vaccines do not protect
– Variants not licensed
4. • Family coronaviridae
– Genus Coronavirus
• Single stranded RNA
Virus
– High mutation rate
• Envelope of 120 nm
diameter
• Spike projections
about 20 nm in length
(S1)
Infectious Bronchitis Virus (IBV)
5. Infectious Bronchitis Virus (IBV)
• Highly contagious
• Airborne, mechanical vectors
• Short incubation period (18-36h)
• Replicates in respiratory, urinary, genital and
gastrointestinal tract tissues
• Shed in respiratory tract and faeces
– Persists After Clinical Signs Gone
• Not vertically transmitted (trans-ovarian)
• Virus easily killed by disinfectants and heat
– Except in presence of organic material
6. What is an IBV variant (IBVv)?
• IBV virus that have changed (mutated) from the
originally identified Massachusetts (classic)
• Variant = Serotype = Strain
• Generally cross-protect poorly with Mass
vaccines
• Variable pathogenicity
• Worldwide vs. Local distribution
7. Distribution
• 1931 – IBV First reported in the U.S.
• 1940 - Massachusetts strain
• 1951 - Connecticut strain
• 1960s - Worldwide
• 1991 - 793/B (4/91) (UK)
• 1997 - QX genotype (Shandong, China)
• 2000s - Variant Strains
– Europe
• QX, Italy02, 793/B (4/91), D274, B1648
– USA
• Conn, Ark, Del, CAL99, GA98, GA08
– Australia
• T, N1/88, N4//02
– Asia
• 793/B (4/91), QX, QX-like, K2, A2
16. Nephritic-Nephropatogenic
• Some Strains
• Mostly Young Chickens (week 2-5)
• High mortality
– Up to 20%
• Interstitial Nephritis and urolithiasis
– Structural alterations in the tubular epithelial cells of
the kidneys
– Impaired fluid and electrolyte transport
• Renal failure ; diarrhea
• Increased uric acid levels -> GOUT
• Secondary Bacterial Infections ( Mortality)
21. Reproductive
• Highly prevalent in Asia since 2000s
• Some strains
• 2 Critical Times
– Baby chick
– Sexual Maturation and onwards (>16-18wks)
• Variable pathology
– Egg yolk peritonitis
– Drops in egg production
– Oviduct Cysts
– Deterioration in eggshell
– Watery albumen
22. 1.
2.
0w
0w
18wks
65wks18wks
65wks
INFECTION IN BABY CHICKS
No homologous MDA, “false layers”
MATURE INFECTION FROM
DEVELOPMENT OF SEXUAL
MATURITY AND ONWARDS
Egg production loss
Poor egg quality
Reproductive
Period of infection
24. • Baby chicks are exposed to IBVv soon after
they hatch
• If they do not have MA the reproductive tract
is easily infected
• The virus damages the oviduct (ovary?), and
develops abnormalities
• This can lead to birds cannot lay eggs
externally, or poor quality eggs
• Real Damage Unnoticed until beginning of
Lay
Reproductive
Early infection of baby chick
25. • “The younger the chickens when exposed, the
more severe the resulting lesion” - Crinion, 1971
• “pathogenicity [..] lowered with increasing age of
chickens at inoculation” – Crinion, 1971
• Damage
– Height reduction of epithelial cells
– Dilation of the tubular glands
– Glandular hypoplasia
• Reduction of albumen proteins
Reproductive
Age-related susceptibility
26. Benyeda et al., 2009
Reproductive
Variable pathogenicity followed by day-old infection
27. Reproductive
Abnormalities
Jones, 2008
• Occlusion of the oviduct lumen (“false layers” -
hens that cannot lay eggs externally)
• Other alterations in the reproductive tract that
lead to:
– Oviduct / Ovary development
– Poor egg shell quality / Reduced Hatchability
28. Crinion et al., 1970
Reproductive
Abnormalities induced by exposure at day-old
29. • IBV Infection Damages
the Reproductive Tract
• Oviduct of a female
chick infected at day-old
after respiratory
infection
• IF stain shows virus in
epithelium 3 days p.i., Jones 1972
Reproductive
How “false layers” happen?
30. Reproductive
How “false layers” happen?
• Repair Of the Oviduct
After Virus Damage
Causes the Oviduct to
Close
• Cyst Develop During
Growing Period
Jones 1972
34. Reproductive
IBVv in mature hens
1.- Inhalation of
virus
2.- Replication
in trachea and
lungs
3.- Virus
reaches ovary
and oviduct via
bloodstream
UOK
50. Diagnosis
• Difficult in Asia
– No Many Available Labs
• Samples
– Difficulties Due to AI Restrictions
• FTA
• Serum / Tissues
• Laboratories
– UGA-PDRC
– IZE – Italy
– CESAC – Spain
– Deventer - Holland
55. • Mycotoxins play a very important role on IBV
control
• Aflatoxins are potent immunosuppressant agents
Liver Damage > Low Immunoglobulin > Low Immunity
> Vaccination Failures
• Detection / Monitoring Difficult
– Even slightly increased levels should raise flags
Control of IBV
Management - Mycotoxins
57. • First and cheapest barrier of prevention
• Many times neglected especially in PS-Broiler
– Poor structural facilities
– Poor cleaning + disinfection
– Decreased downtime
• Poor biosecurity = High challenge for baby chick
Control of IBV
Biosecurity
58. • Seal the Farm …Keep disease out
– Do not let disease come into your farm
• Avoid unnecessary visits
• Disinfection of equipment
• Shower In-Out
• Clothing
• Manure
• Mortality / Cull disposal
Control of IBV
Biosecurity - Basics
62. Disease
Lifespan away from
birds
Infectious Bursal Disease Months
Coccidiosis Months
Fowl Cholera Weeks
Coryza Hours to Days
Marek's Disease Months to Years
Newcastle Disease Days to Weeks
Mycoplasmosis (MG, MS) Hours to Days
Salmonellosis (Pullorum) Weeks
Infectious Bronchitis Days to Weeks
Control of IBV
Biosecurity – Cleaning and Disinfection
63. • Very important to allow resting the farm
• Dry – UV -> bad for pathogens
• Minimum 14d Broilers / 1 months PS / 2 months GP
• Do Not Rush to Place Birds!
Control of IBV
Biosecurity – Downtime
65. • Most Controversial Area
• Research Work Shows good protection by
combination of Mass + Variant
– No need for new vaccine for every new variant
– Research Done of Protection Respiratory Tract
• NEED MORE RESEARCH ON THIS AREA
• Interaction of Maternal Antibodies
– Lack Maternal Antibodies for IBVv in certain ares
• Some Programs: Mass day 0 + Variant day 14
– Does not take consideration of “day 0 challenge”
• Poor Biosecurity + Management
Control of IBV
Vaccination
66. • Early challenge difficult to control with vaccination
– Maternal antibodies are a great asset
• Limited research on IBVv and maternal antibodies
– Wit JJ (Sjaak) de, 2011
• Generally homologous serotypes protect well from IBV
– not that good heterologous challenges
• Baby chicks lack Maternal Antibodies specific for the
variant present
– ALMOST SPF BIRDS
• Biosecurity + Adjustment of Vaccination
Control of IBV
Vaccination – Maternal Antibodies
67. Control of IBV
Vaccination – Factors
• Determination of challenge
– Laboratory Confirmation
• Vaccine selection
• Vaccine scheduling
• Vaccination hatchery vs. farm
• Vaccine handling / application
• Control vaccine reactions
• Revaccination during production
– MAb
• Titer Monitoring
68. Control of IBV
Vaccination – Breeders High Challenge
• Day 0 – Mass + Variant
• Day 14 Mass
• Week 4 - Mass
• Week 6 – Variant
• Week 8 – Mass
• Week 12 – IB (K) Multi Variant
• Week 16 – Variant + IB (K) Multi Variant
Disclaimer: This is an example of IBVv vaccination program. Always consult your
veterinarian before implementing a new vaccination program in your flocks
69. Control of IBV
Vaccination – Broilers High Challenge
• Day 0 – Mass + Variant
• Day 12-14 Mass
Disclaimer: This is an example of IBVv vaccination program. Always consult your
veterinarian before implementing a new vaccination program in your flocks
70. First vaccine Challenge Outcome
Mass type Mass type Protection
793/B No protectionMass type
None or Little protection Against Non–Mass Strains
Control of IBV
IB Live Vaccination
Based on Intervet
71. First vaccine Challenge Outcome
IB88 -
4/91
Mass type
Protection793/B
No protection
IB88 -
4/91
Even Revaccination With Same Vaccine Strain Will
Not Give Cross Protection
Control of IBV
IB Live Vaccination
Based on Intervet
72. First vaccine Challenge Outcome
Mass type
Protection793/B
IB88 -
4/91*
IB88 -
4/91*
Second vaccine
Mass
Mass
Protection
Expected to give general
protection against other IBV
*Second Vaccine can be combined with First Vaccine to cover opportunity
window at day of age
Control of IBV
IB Live Vaccination
73. First vaccine Challenge Outcome
D388 (QX)IB88 -
4/91
Second vaccine
Mass Protection
Control of IBV
IB Live Vaccination
There is no need to develop a vaccine for each new serotype, as
different “old” serotypes generally confer protection over “new”
serotypes – PROTECTOTYPE CONCEPT
Based on Intervet
74. • Classic
– H120; Ma5; M41; H52; 28/86
• Variants
– 793/B
• Nobilis 4/91 (793/B) (SP-Intervet)
• Gallivac IB88 (793/B) (Merial)
• Vir 117 (793/B) (BioVac)
– D274
• IB Primer (Holland + D274) (Pfizer)
• Nobilis IBmulti / IB3 (SP-Intervet)
• Vaksindo (M41, QX, IB 771)
– Others
• Conn (SP)
• Poulvac QX (Pfizer)
• Nobilis D1466 (SP-Intervet)
• Ark-99 (Pfizer)
• QX-like strain Korea (K2)
• Australian VIC S / A3
Control of IBV
Vaccination – Vaccines Available
75. The Road Ahead
IBVv Challenges
• Overlapping with Other Diseases
– ND / AI / APV / Mycoplasma / Others
• Diagnosis
– Laboratories
• Poor Biosecurity
• Vaccine Availability
– License
• Vaccine Misuse
– Technique / Scheduling
76. Summary - IBV
• IBV Variant strains have been reported with high
prevalence in many Asian countries and are causing
significant damage
• Diagnostics and monitoring are sometimes scarce,
however utmost necessary to control the disease
• Biosecurity + Vaccination are currently the most effective
ways of protection
• Current Vaccination programs across the area are not
homogenous and are based in combination of scientific
and empiric beliefs, further research is needed