Nowadays vaccination is often reported as the cause of disease outbreaks. To ward off this misconception (vaccines are made to save the masses not to risk their lives)or to understand vaccination failures, it is necessary to understand the difference between a field strain causing the disease and a vaccine strain having attenuated virulence. This presentation talks about DIVA and DISA vaccines too.

1. Differentiation of field isolates (wild) from
vaccine strains (Marker, DIVA & DISA vaccines)
DOI: 10.13140/RG.2.2.17023.18086
Bhoj R Singh
Division of Epidemiology, ICAR-IVRI, Izatnagar-
243122, India
brs1762@gmail.com
Available at:
https://www.researchgate.net/publication/372418171_Differentiation_of_fiel
d_isolates_wild_from_vaccine_strains_Marker_DIVA_DISA_vaccines
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2. Some definitions
• Isolate: A group of descendants from a single isolated colony of a species.
Many isolates can be there from a single case and unless proven to belong
to different strains are considered as single strains.
• Strain: Collective descendants of a common ancestor sharing a uniform
morphological or physiological or genetic character. A genetic variant or
subtype of a microorganism within a genetic species or a group of
organisms within a species that differ in trivial ways from similar
groups in the same species. The concept of a strain is inherently artificial
a concepts, created with a specific intent for genetic isolation/
differentiation among groups of the same species. A group of organisms
that belong to the same species but share certain genetic characteristics not
found in other members of the species.
• As per Bergey’s Manual of systematic Bacteriology a strain is made up of
descendants of single isolation in pure culture and usually made up of a
succession of cultures ultimately derived from an initial single colony.
• In nature, at any one point in time a strain is rarely ‘pure’ in al respect,
because competition resulting in evolution is a incessant process and the
number of strains just varies by one point mutation or more may be present
there.
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3. • Clone: A strain derived from a single cell/ colony and is
typically quarantined by the physical constraints. A
population descending from a single parent originating with
asexual reproduction. Many similar isolates from a small or
big geographical area may belong to a simple clone but not
a single strain.
• Field isolates: Isolates of a pathogen from cases of illness
or healthy subjects and or environmental sources.
• Field Strains: Isolates from a defined geographical area
belonging to the same strain.
• Vaccine strains: Strain(s) used for commercial production
of the vaccine(s).
• Based on DNA-Pairing data, strains with >70% pairing and
with >97% rRNA similarity constitute a species.
• Two strains may differ by single nucleotide pair.
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4. How to differentiate between a field isolate
and a vaccine strain?
• Growth and physiological characteristics in different
environmental conditions (Host, temperature, media, oxygen
tension, growth, pH, requirement for essential amino acids/
fatty acids etc.).
• Difference pathogenicity/ virulence
• Markers available in vaccine strains.
• Difference in immune response (DIVA concept).
• WGS or targeted sequencing/ detection of the deletions/
insertions used as markers through PCR and similar genetic
characters.
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5. Marker vaccine
• Marker strains of vaccines: Vaccine strains can be differentiated either
through their morphological, growth, physiological or genetic make up.
Marker vaccines are based on deletions/ insertion mutants of wild-type
pathogens, subunit vaccines and inactivated whole virus vaccines.
• DIVA Vaccines (capable of Differentiation of infected from vaccinated):
These are certainly marker vaccines but all marker vaccines are not DIVA
vaccines. The immune response to DIVA vaccine can be differentiated
from natural infection immune response.
• DIVA test: Immunological tests capable to differentiate between immune
response induced by natural infection and vaccination.
• DIVA vaccines are useful for the designated purpose when used along
with companion DIVA test.
• SIVA (Segregating Infected and Vaccinated Animal) vaccines
• DISA (Disabled Infectious Single Animal) vaccines. Disabled in the sense
that the vaccine does not cause viraemia/ bacteraemia or excreted/
secreted thus remains to the animal which remains to the vaccinated
animal only but are DIVA in all other respect. All inactivated/ killed DIVA
vaccines belongs to this group. e.g. NPS deleted Bluetongue vaccine,
disabled to multiply in host.
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6. Vaccine Strain used
Covaxin NIV-2020-770
BCG M. bovis strain obtained after 230 consecutive in vitro passages over
13 years at the Pasteur Institute of Lille in 1921, Pasteur 1173P2
BCG-AJ vaccine M. bovis BCG (Bacillus Calmette-Guerin), Danish strain 1331,
isolated from a cat, used in high risk groups
Smallpox Vaccinia virus
Vaccinia virus used as candidates
for recombinant vaccines
Modified vaccinia Ankara (MVA) and LC16m8
HS Vaccine P52 of Pasteurella multocida type B
FMD Vaccine FUTVAC: for type O-IND/O/R2/75, type A-IND/A/40/2000, type
Asia1-IND/Asia1/63/72
PPR vaccine PPRV/Sungri/96 strain
Goat Pox vaccine Uttarkashi Strain
Anthrax spore vaccine Sterne strain
Brucella vaccine Strain 19, 82,75/79-AB, RB51, Brucella abortus, Rev-1 B. melitensis
LSD Ranchi strain
Sheep pox SPPV Srin 38/00
Classical swine fevere IVRI-CSF-BS 6

7. DIVA vaccine examples
• Canine Leish-Tech® CEVA Animal Health Leishmania
• Lentifend® Laboratorios Leti Leishmania
• Feline PureVAX® Recombinant FeLV Boehringer Ingelheim Feline Leukemia
Virus
• Swine Porcilis® Begonia Merck Animal Health Suid Herpesvirus 1
• Auskipra® GN Hipra Suid Herpesvirus 1
• Suvaxyn® CSF Marker Zoetis Classical Swine Fever Virus
• Bovine Adt.A24 FMD GenVec Foot and Mouth Disease
• Bovilis® IBR Marker Live Intervet Bovine Herpesvirus-1
• Hiprabovis® IBR Marker Live Hipra Bovine Herpesvirus-1
• Bayovac IBR Marker Vivum Bayer Bovine Herpesvirus-1
• Bayovac IBR Marker Inactivum Bayer Bovine Herpesvirus-1
• Rispoval® IBR-Marker Inactivated Zoetis Bovine Herpesvirus-1
• Rispoval® IBR-Marker Live Zoetis Bovine Herpesvirus-1
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8. DIVA tests
• All DIVA vaccines have companion DIVA tests.
• Some conventional vaccines can be converted
to DIVA after developing DIVA tests as
– NSPs based: 3AB3 ELISA for use in FMD DIVA
vaccination in India.
– NS3 protein-based ELISA or LF assays for classical
swine fever
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9. Quiz
1. Name the conventional vaccines made for
DIVA afterwards their development.
2. Enlist the methodologies and concepts used
for the development of DIVA vaccines.
3. List the advantages of using DIVA vaccines.
4. What are the differences between a marker
vaccine and a DIVA vaccine?
5. Name the different types of markers used for
vaccines in past concerning the purpose.
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