3A: Geographic Strain Differentiation of S. japonicum in the Philippines Using Microsatellite Markers

• Large number of eggs produced

• Zoonotic nature

2 reasons why S. japonicum is the most virulent of all strains.

Determine schistosome genetic diversity due to their codominant expression & ability to serve as neutral markers

The purpose of microsatellite markers.

• Easy observation of heterozygosity

• Reasonable number of alleles per polymorphic locus in samples

2 reasons why microsatellite markers are a better option compared to RAPD & MtDNA.

• Catarman

• Gonzaga

• New Corella

• Irosin

• Talibon

• Alang-Alang

• Socorro

7 endemic municipalities of the Oncomelania hupensis snail.

Mesenteric veins after 45 days

Where and when adult S. japonicum worms are harvested from mice.

1. RRPS

2. M5A

3. TS2

4. MPA

5. 2AAA

6. J5

7. SJP1

8. SJP5

9. SJP6

10. SJP9

The 10 microsatellite loci DNA was analyzed against.

• 6-FAM

• VIC

• Ned Dyes

3 things that the 5’end of the forward primer for each locus is labeled by.

Gonzaga

The S. japonicum from this municipality was used as the reference genotype.

Yamanashi Strain

This S. japonicum strain was used as a control & outgroup.

Used to confirm the microsatellite markers & could differentiate between samples from different origins.

What the specific purpose of the Yamanashi strain of S. japonicum was for.

• Degree of genetic differentiation varied between endemic areas

• Cercariae from a snail with one miracidium are genetically identical

2 results of the study.

Catarman

The municipality that displayed the highest genetic diversity.

Alang-Alang

The municipality that displayed the lowest genetic diversity.

Irosin

The municipality that displayed the highest allelic richness.

Alang-Alang

The municipality that displayed the lowest allelic richness.

Population-specific Inbreeding Coefficient

What measures the extent of nonrandom mating.

Increases homozygosity

The effect of inbreeding on alleles.

Pairwise FST

What indicated varied levels of pairwise population genetic differentiation.

Great genetic differentiation in New Corolla samples with greater genetic variation in the samples within the population rather than among populations.

The finding of the Pairwise FST.

No geographical structure among S. japonicum populations

The population structure showed by PCoA.

Clustering into 2 groups

The general finding of the neighbor joining tree.

• Group 1: Catarman, New Corella, Gonzaga, & Talibon

• Group 2: Alang-Alang, Socorro, & Irosin

The members of each of the 2 groups formed by the neighbor joining tree.

No correlation between clustering of populations & their geographic distribution in the neighbor joining tree.

The relationship of clustering populations found in the neighbor joining tree.

Gene Flow

What the 2 subgroups in Catarman samples possibly accounting for high genetic variation might suggest.

Prevalence of infection was directly proportional to the number of alleles

The relationship of infection prevalence & allele number.

Prolonged utilization of Praziquantel from annual MDA due to Leyte being one of the oldest endemic foci in the Philippines

The possible reason as to why the low number of alleles were observed in locations where prevalence of infection was high like in Alang-Alang.

Geographic Isolation

The main driver for genetic differentiation in New Corella.

Infected human migration driven by a major Philippine National Oil Company geothermal project recruiting workers form Visayas & Mindanao

How parasites were introduced to Gonzaga.

Sustain ongoing transmission & high parasite genetic diversity

The relevance of reservoir hosts.

Carabaos & Dogs

2 examples of reservoir hosts.

Carabaos

How ongoing transmission persists in Talibon, a near-elimination zone with no recent human cases.

• Continuous flooding

• Animal trade

2 scenarios that facilitate host-parasite contact & host movement.

Persistent inter-village parasite transmission

What the lack of spatial structuring & ongoing gene flow indicate.

Low, <50%

The compliance rates for annual praziquantel 40 mg /kg treatment.

Multiple co-infecting genotypes

What reduces host immune response efficacy & increase transmission success.

• Monitoring snail genetics

• Track parasite genetic diversity before & after MDA

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