Yersinia pestis in Madagascar paper

Question 1

What

Answer 1

3 pandemic of plague
6th century (Procopius)
14th century (Boccacio)
• 1894 (Camus)

Question 2

1894

Answer 2

Alexandre Yersin identify a gram-negative rod:
Yersinia pestis (then Pasteurella pestis), and its reservoir:
rats

Question 3

1898

Answer 3

Paul Louis Simond: Y. pestis transmitted by fleas

Question 4

Y. pestis is subdivided into ..

Answer 4

three biovars
Antiqua
•Medievalis
•Orientalis
•Because strains in areas of antique foci are not
Orientalis, then Orientalis must be associated
with 3rd pandemic

Question 5

Pulse Field Gel Electrophoresis (PFGE)

Answer 5

SpeI DNA patterns of 8 strains of Y. pestis closely

related to biovars (Lucier & Brubaker 1992

Question 6

I-CeuI

Answer 6

DNA patterns of 9 strains also closely related
to biovars (Rakin & Heeseman 1995)

Question 7

RFLP

Answer 7

of 16S rRNA genes of 70 strains can be subdivided into 16 ribotypes

Question 8

Orientalis

Answer 8

Orientalis correspond to Ribotype B (Guiyoule et
al. 1994)
But some Orientalis have ribotype G or E
1994 outbreak in India: ribotype S

Question 9

Suggest that within a century:

Answer 9

Chromosomal rearrangement leading to new

strains

Question 10

Madagascar:

Answer 10

I. Plague arrived first time in 3rd pandemic
II. Risks of extraneous plague importation
limited because it is an island
III. Wide range of strains and epidemiological
characteristics available

Question 11

Objective of paper

Answer 11

To demonstrate that in Madagascar Y. pestis strains
collected
1. Before 1982 had classical ribotype B
2. After 1982 new strains with ribotype R, Q
and T emerged in a specific region of the
island and are now well established in
ecosystem
3. Association between genomic profiles,
ribotypes, and plasmids

Question 12

Methods

Answer 12

All are biovar Orientalis (negative for glycerol fermentation,
positive for nitrate reduction to nitrite)
Strains grown on Tryptic soy agar plates
DNA extracted and digested with EcoRI or EcoRV
0.8% agarose gel electrophoresis
Then hybridization with 16S+23S rRNA probes
Plasmid extracted and digested with EcoRV
PFGE
genomic DNA in agarose plugs
angle of 120opulse, 1 to 10 s over 29 h
Antibiotic resistance profile with disk

Question 13

how many strains of Y. pestis isolated between 1939 and 1996

Answer 13

187

Question 14

Results

Answer 14

Ribotype B: RI.1 + RV.2
Ribotype R: RI.12 + RV.12
Ribotype Q: RI.13 + RV.2
Ribotype T: RI.15 + RV.2

R: isolated from Ambositra prefecture
Q: isolated from Ambohimahasoa prefecture
High plateaus

Question 15

identification of how many new ribotypes strains

Answer 15

59

Question 16

How many isolates from Ambositra

Answer 16

98

Question 17

How many isolates from Ambohimahasoa

Answer 17

33

Question 18

Before 1982

Answer 18

13 strains B only

Question 19

1982-1994

Answer 19

strains R only from Ambositra

All strains within 20 km

Question 20

1994

Answer 20

first time R is outside this region

Question 21

1983

Answer 21

Q in areas wide apart
so origin before 1983
Ambositra and Ambohimahasoa

Strain 22/95: mix of Q and R in one female, 40
years old

Question 22

1994

Answer 22

: T in Ambohimahasoa only

Question 23

Evolution of new variants in Ambositra and Ambohimahasoa

Longitudinal study

Answer 23

I. Total number of isolates has increased since
1980’s
II. Ribotype B remains major ribotype in this region
III. Since 1982 and 1983: Q and R isolated more
frequently over increasingly wider areas
42% of strains since 1990 are Q and R

Question 24

how many pulsotypes

Answer 24

11
B: pulsotypes 1-8
R: pulsotypes 10-11
Q: pulsotype 9

Question 25

clonal origin

Answer 25

Consistent pulsotype for Q and R

Question 26

Three plasmids

Answer 26

I. pFra/Tox: fraction 1 antigen and a murine
toxin
II. pYV: virulence plasmid common to three
pathogenic Yersinia species
III. pPla: bacteriocin pesticin and
plasminogen activator

Question 27

Three plasmid profiles

Answer 27

P1: Ribotype B and R
P2: Ribotype Q
P3: ribotype T

Question 28

is there Phenotypic differences associated with ribotypes

Answer 28

no

Question 29

Plague introduced in 1898 by

Answer 29

ship from India

Question 30

Unlikely that new strains of Y. pestis introduced from

abroad as..

Answer 30

I. No Y. pestis in the world display ribotypes
Q, R, T
II. New variants isolated from high plateaus
III. They appeared recently many years after
establishment of surveillance
IV. Introduction of 3 different strains in 3
different times is unlikely
V. Little divergence in pulsotypes

Question 31

what may reflect
intensive multiplication and circulation of the
microorganism

Answer 31

Isolation of 3 new variant from same region

Question 32

Spreading of this strain suggest ….

Answer 32

it is now

colonizing new areas

Question 33

R, Q, and T: different from original type (B) in their…

Answer 33

Ribotypes (rRNA)
Pulsotypes (genomic DNA)
Plasmid profiles (plasmid DNA)

Question 34

what is explained by a local
modification of the original Y. pestis that spread
over the world

Answer 34

Isolation of strains of biovar Orientalis with a ribotype
other than B in countries such as Madagascar,
India, Vietnam

Question 35

Based on comparative genomic analysis: genome of 1347-1349…

Answer 35

appears as ancestor of all contemporary Y. pestis. (biovars are
following environmental adaptation of post 1347 pandemic)
• Other factors such as:
– environment
– vector dynamics
– host susceptibility