36
SANARIA SANARIA PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG RESISTANCE (THE SELFISH GAMETOCYTE) Dr Peter Billingsley Sanaria Inc. 9800 Medical Center Drive, Rockville, MD 20850, USA. 4/23/2008 1

PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

  • Upload
    others

  • View
    1

  • Download
    0

Embed Size (px)

Citation preview

Page 1: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG RESISTANCE

(THE SELFISH GAMETOCYTE)

Dr Peter BillingsleySanaria Inc.

9800 Medical Center Drive,Rockville, MD 20850, USA.

4/23/2008 1

Page 2: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

INTRODUCTION

• Malaria in the mosquito

• Dynamics of transmission through the

mosquito

• Manipulation of transmission by the

parasite

• Drug treatments, gametocytes and

transmission

• Mosquitoes and drug resistance

4/23/2008 2RFF Meeting, Kruger, March‐April 2008

Page 3: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

PLASMODIUM SPOROGONIC CYCLE

4/23/2008 3RFF Meeting, Kruger, March‐April 2008

Page 4: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

LIFE AND DEATH IN THE MOSQUITO

4/23/2008 4RFF Meeting, Kruger, March‐April 2008

Baton & Ranford‐Cartwright 2005 Trends Parasitol 22:574‐580

Page 5: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

LIFE AND DEATH IN THE MOSQUITO

4/23/2008 5RFF Meeting, Kruger, March‐April 2008

Vaughan 2006 Trends Parasitol 23:63‐70

Page 6: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

LIFE AND DEATH IN THE MOSQUITO

• k = “killing power”

• Logarithmic

• Here K =2.25 = 178-fold loss

4/23/2008 6RFF Meeting, Kruger, March‐April 2008

Vaughan 2006 Trends Parasitol 23:63‐70

Page 7: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

LIFE AND DEATH IN THE MOSQUITO

4/23/2008 7RFF Meeting, Kruger, March‐April 2008

Vaughan 2006 Trends Parasitol 23:63‐70

Page 8: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

LIFE AND DEATH IN THE MOSQUITO

4/23/2008 8RFF Meeting, Kruger, March‐April 2008

Gouagna et al. 1998 Trop Med Int Health 3:21‐28

Page 9: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

LIFE AND DEATH IN THE MOSQUITO

4/23/2008 9RFF Meeting, Kruger, March‐April 2008

Sinden et al. 2007 PLoS Pathogens 3(12): e195. doi:10.1371/journal.ppat.0030195

Page 10: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

LIFE AND DEATH IN THE MOSQUITO

4/23/2008 10RFF Meeting, Kruger, March‐April 2008

Sinden et al. 2007 PLoS Pathogens 3(12): e195. doi:10.1371/journal.ppat.0030195

Page 11: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

LIFE AND DEATH IN THE MOSQUITO

4/23/2008 11RFF Meeting, Kruger, March‐April 2008

Gouagna et al. 1998 Trop Med Int Health 3:21‐28

Page 12: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIA

RFF Meeting, Kruger, March‐April 2008

Page 13: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

Page 14: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIA

HETEROGENEITY OF EXPOSURE 

4/23/2008 14RFF Meeting, Kruger, March‐April 2008

Page 15: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

SPATIAL HETEROGENEITY OF ANTIBODY RESPONSES TO MOSQUITO SALIVA

4/23/2008 15RFF Meeting, Kruger, March‐April 2008

Page 16: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIA

0

5

10

15

0 2 4 6 8 10 12 14

0

2

4

6

8

10

12

14

0 2 4 6 8 10 12 14

0

2

4

6

8

10

12

14

16

0 2 4 6 8 10 12 14

0

2

4

6

8

10

12

14

0 2 4 6 8 10 12 14Per

cen

t in

fect

ed c

ells

at

ga

met

ocy

te s

tag

e

Time post infection (days)

MOSQUITO PROBING AND GAMETOCYTE KINETICS

• Proportion of parasites

at the gametocyte stage

is higher in mice

exposed to 50 probing

mosquitoes.

• Peak gametocytes are

advanced by 2 days in

mice exposed to

mosquitoes

4/23/2008 16RFF Meeting, Kruger, March‐April 2008

Page 17: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIA

MOSQUITO PROBING AND GAMETOCYTE KINETICS

• Total number parasites

increased; T50% advanced by

1.2-1.64 days

• Total number of gametocytes

increased; T50% advanced by

2.0-2.47 days

• Increased rate of gametocyte

production

0

1

2

3

4

5

6

7

0 2 4 6 8 10 12 14

Time post infection (days)

Cum

ulative g

0

10

20

30

40

50

0 2 4 6 8 10 12 14

Cumulative pro

portion of

gametocytes

0

10

20

30

40

50

60

0 2 4 6 8 10 12 14Cum

ulative m

ean p

ara

sitaem

ia

4/23/2008 17RFF Meeting, Kruger, March‐April 2008

Page 18: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIA

P. BERGHEI INGESTION: GAMETOCYTE BIAS IN THE BLOODMEAL

0

5

10

15

20

25

30

35

40

0 5 10 15 20 25 30 35 40

Percent Parasitaemia in Mouse

Pe

rce

nt

Pa

rasi

tae

mia

in

Blo

od

me

al

Parasites

0

2

4

6

8

10

12

0 2 4 6 8 10 12

Gametocytes in Mouse Blood

Ga

me

tocyte

s in

Mo

squ

ito

Blo

od

me

al

Gametocytes

4/23/2008 18RFF Meeting, Kruger, March‐April 2008

Page 19: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

MOSQUITOES PREFER GAMETOCYTE CARRIERS

4/23/2008 19RFF Meeting, Kruger, March‐April 2008

Lacroix et al. (2005) 3: e298.

Page 20: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

EMERGENCE OF COMPETING CLONES

• P. chabaudi

• ‘Minority’ clones in host transmitted to mosquito

• Population in vector is disproportionately higher than in host.

• Mixed infections may

transmit at higher rate than clonal infections

4/23/2008 20RFF Meeting, Kruger, March‐April 2008

Taylor et al., Proc. R. Soc. Lond. B (1997) 264, 927‐935

Page 21: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

OLD MOSQUITOES ARE DANGEROUS….

4/23/2008 21RFF Meeting, Kruger, March‐April 2008

Page 22: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

EPIDEMIOLOGICAL IMPLICATIONS

• Individuals exposed to more mosquitoes make even greater contribution to transmission than thought.– Greater induction of gametocytes

– Greater infection to the mosquito (proportional and absolute)

– Greater infection from the mosquito (absolute)

• Mosquito-infective gametocytes produced even when ‘clone’ is in minority

• Gametocyte-infected individuals attract mosquitoes

4/23/2008 22RFF Meeting, Kruger, March‐April 2008

Page 23: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

Page 24: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

STRUCTURE OF PARASITE POPULATIONS IN MOSQUITOES

Inbreeding coefficient

statistics for P. falciparum

oocysts collected from A.

gambiae (G) and A.

funestus (F) in Cameroon

and Kenya.

Annan et al., 2007 PNAS 104:  7987–7992

FST

FIS

4/23/2008 24RFF Meeting, Kruger, March‐April 2008

Page 25: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

STRUCTURE OF PARASITE POPULATIONS IN MOSQUITOES

• P. falciparum is a fully ‘sexual’ organism

• Oocysts collected in Malawi (and PNG) show evidence of random

mating and no linkage disequilibrium.

Mzilahowa T, et al., 2007) PLoS ONE 2(7): e613.doi:10.1371/journal.pone.0000613

4/23/2008 25RFF Meeting, Kruger, March‐April 2008

Page 26: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

PARASITE AGGREGATION AND TRANSMISSION

4/23/2008 26RFF Meeting, Kruger, March‐April 2008

Vaughan 2006 Trends Parasitol 23:63‐70

Page 27: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIA

GAMETOCYTAEMIA IS INDUCED BY ANTIMALARIALS

• Kaplan-Meier estimator of the

time to gametocytaemia for

untreated children (dotted line)

and SP-treated children (solid

line).

• Groups differed in asexual

parasite density at enrolment.

Gametocyte carriers on day 0

were excluded, as well as

children who reported the use of

antimalarial drugs prior to

enrolment. Log-rank P = 0.05

Bouesma et al., Malaria Journal 2004, 3:18

4/23/2008 27RFF Meeting, Kruger, March‐April 2008

Page 28: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

GAMETOCYTES ARE INFECTIVE AFTER MALARIA THERAPY

4/23/2008 28RFF Meeting, Kruger, March‐April 2008

Bouesma et al., J Inf Dis 2006; 193:1151–9

Page 29: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

EMERGENCE OF DRUG RESISTANT-

PARASITES FROM MIXED INFECTIONS

• Total numbers of AS (A) and CB (B) parasites produced over the whole infection in single and mixed (AS and CB simultaneously or 3 days apart) infections in experiment 1 (mean1 SEM). See table 1 for the numbers of mice on which data points are based.

4/23/2008 29RFF Meeting, Kruger, March‐April 2008

De Roode et al., 2005 166: 531‐542

Page 30: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

EMERGENCE OF GAMETOCYTES POST-COMBINATION THERAPY

4/23/2008 30RFF Meeting, Kruger, March‐April 2008

El‐Sayed et al., (2007) PLoS ONE 2:e1311. doi:10.1371/journal.pone.0001311

Page 31: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

PROLONGED GAMETOCYTE INFECTIVITY

FOLLOWING DRUG TREATMENTS

4/23/2008 31RFF Meeting, Kruger, March‐April 2008

Hallett et al., (2006) PLoS Clin Trials 1(3): e15. DOI: 10.1371/journal.  pctr.0010015

Page 32: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

TRANSMISSION ADVANTAGE OF RESISTANT GENOTYPES

4/23/2008 32RFF Meeting, Kruger, March‐April 2008

“..the presence of the four‐locusmultidrug‐resistant haplotype TYRG (consisting of mutations pfcrt‐76T, pfmdr1‐86Y, pfdhfr‐59R, and pfdhps‐437G) was associated with significantly higher oocyst burdens after treatment with the combination CQ/SP.

Hallett et al., (2006) PLoS Clin Trials 1(3): e15. DOI: 10.1371/journal.  pctr.0010015

Page 33: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

DRUG RESISTANT GENOTYPES AND TRANSMISSION

• Treated with CQ and SP (Fansidar)

• Parasites examined pre-treatment and days 7, 14 , 21 (transmission

season), and 80 (start of the dry season).

• Gametocyte carriage– Microscopy: increased significantly following CQ and SP treatment, days 7 and 14.

– RT-PCR: no significant difference in gametocyte rate days 0 through 14.

• Day 80: 33% in CQ- and 8% in SP-treated group.

• Alleles associated with drug resistance of P. falciparum to

chloroquine (pfcrt and pfmdr1) and pyrimethamine (dhfr) increased in

frequency through time following both drug treatments.

• Infections with drug-resistant parasites tended to have higher

gametocyte prevalence than drug-sensitive infections.

4/23/2008 33

Ali et al., 2006 Trans R Soc Trop Med Hyg. 100:176‐83

4/23/2008 33RFF Meeting, Kruger, March‐April 2008

Page 34: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIA

EXTENDING THE  INFECTIOUS WINDOW

4/23/2008 34

RFF Meeting, Kruger, March‐April 2008

Schneider et al., (2006) Int J Parasitol 36: 403–408

• Microscopically detectable parasites observed to day 28

• PCR detectable parasites always present

• Still approx. 20 % prevalence after 28 days

Page 35: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIASANARIA

THE SELFISH GAMETOCYTE AND DRUG RESISTANCE

• Gametocyte manipulates:

– Mosquito host location

– Mosquito blood feeding

– Gametocyte uptake

• Increases probability of sexual recombination and infection

through the mosquito.

• Gametocytes

– increase in number post-drug treatment

– maintain low densities for prolonged periods in host

– Are infectious long after treatment

• Drug resistant gametocytes

– Increase in frequency in host and mosquitoes post-treatment

– Have an extended period in circulation even after combination

treatments

4/23/2008 35RFF Meeting, Kruger, March‐April 2008

Page 36: PLASMODIUM IN THE MOSQUITO: CONTRIBUTION TO DRUG … · 2018. 8. 31. · INTRODUCTION • Malaria in the ... gam eotcytes 0 10 20 30 40 50 60 Cum 0 246 8 101214 ulative m ean parasitaemi

SANARIA

RFF Meeting, Kruger, March‐April 20084/23/2008 36