BAMA ARTICLE ASSIGNMENT 7/30/13

Preventing the spread of infectious diseases

through the endosymbiotic relationships

with Wolbachia

By Lois CrozierBAMA Teacher

Johnsonburg Area School District, Johnsonburg, PA

TSETSE-WOLBCHIA SYMBIOSIS: COMES OF AGE AND HAS GREAT POTENTIAL FOR PEST AND DISEASE CONTROLDoudoumis, V., Alma, U., Askoy, E., Abd-Alla, A. M. M., Tsiamis, G., Brelsfoard, C., Aksoy, S., & Bourtzis, K. (2013). Tsetse-wolbachia symbiosis: Comes of age and has great potential for pest and disease control. Journal of Invertebrate Pathology, 112, S94-S103. doi: PMID: 22835476

Article:

ORDER: DIPTERAFAMILY: GLOSSINIDAEGENUS: GLOSSINA

Vector in the transmission of Trypanosomiasis the cause of African Sleeping Sickness

Tsetse fly

MICROFILARIAE ! WHAT ARE THEY?

thread-like parasitic nematodes (roundworms) transmitted by arthropod vectors

microfilariae infect vector arthropods, in which they mature to larvae

adult worms inhabit specific tissues where they mate and produce microfilariae, thread-like larvae.

Tsetse fly

carries flagellat

e to host

animal other then a human

African Animal Trypanosomia

sis(AAT)

human

Human African

Trypanosomiasis

(HAT)

THE COST OF TRYPANOSOMIASIS

60 million people live in regions where the parasite is located.

African Animal Trypanosomiasis is the biggest problem in preventing the increase of livestock populations

African Animal Trypanosomiasis

is the leading cause of hunger and poverty

THE POINT?

Current vector control is not sustainable or environmentally friendly.

Urgent need for pesticide free, environmentally friendly method of vector control

Current vector control is not sustainable or environmentally friendly.

Urgent need for pesticide free, environmentally friendly method of vector control

http://www.rochester.edu/college/bio/labs/WerrenLab/WerrenLab-WolbachiaBiology.html http://www.who.int/mediacentre/factsheets/fs259/en/http://emedicine.medscape.com/article/214581-overview

Filarial Nematodes and Wolbachia

Mutualistic relationship with Filarial nematodes

Plays a role in nematode survival and reproduction.

parasite:Trypanosoma

brucei gambiens

parasite:Trypanosoma

brucei rhodesiense

African Sleeping Sickness

Parasite:Trypanosoma

cruzi

Chagas Disease

Reproductive parasitic

relationship with Tsetse flies

Vector:Tsetse fly is the host for each of these parasites

3 SYMBIOTIC BACTERIA IN THE TSETSE FLY

1. Wigglesworth glossinidiaFound in 2 distinct populations in the insect: Intracellular population in the specialized epithelial cells in the end gutPlays a role in providing essential vitamins and minerals absent from a blood diet

Extracellular population in female milk secretionMethod of transmission to the intrauterine larvae through mothers milk.

An absence of Wigglesworth g. results in female sterilityWigglesworth is heterozygous in the natural populationinfluences host juvenile larvae development of immune

system

2.Sodalis glossinidiusPresent in all lab populations and heterozygous in natural

populationsDistributed in many tissues including haemolymph,

salivary gland, milk gland, an midgut where it lives close to where trypanosomes develop.

Passed to intrauterine larva through mothers milk

3. Wolbachia pipiens Obligatory endosymbiont

(lives within the organism and either the endosymbiont or the host cannot survive without the other)

maternally transmitted Found in reproductive tissue of insect

EFFECTS OF WOLBACHIA PIPIENS IN HOST

Parthenogenesis ( female reproduction without

fertilization ) Feminization ( male killing, male zygotes

don’t survive ) Cytoplasmic Incompatibility (CI)

Most common Can be unidirectional or bidirectional Results in a reduction in the population of the host

ANOTHER METHOD TO STOP TRANSMISSION

Incompatible Insect Technique (IIT)

IIT causes sterility due to the presence of a Wolbachia strain genetically capable of inducing cytoplasmic incompatibility.

IIT Has been done successfully in the lab and in the field

INCOMPATIBLE INSECT TECHNIQUE (IIT)

Wolbachia-induced CI can control populations of agricultural pests and disease vectors

might someday play a role in spreading or replacing desired phenotypes

(because infected females have a reproductive advantage of passing their DNA onto the offspring )

Methods for inducing the transfer of desired genes have yet to be worked out fully.

Higher frequency

in the Population

Proportional to

the number of

infected males

INFECTED UNINFECTED OFFSPRINGWITH WITHWOLBACHIA WOLBACHIA

No

Yes

Yes

Yes

No

Yes

YesYes

GLOSSINIA AND WOLBACHIA

vector genus of tsetse flies is Glossinia

http://www.who.int/mediacentre/factsheets/fs259/en/

Using 16S rRNA based PCR analysis 3,750 flies from 12 species from 10

African countries were tested Found multiple cytoplasmic strains and

Wolbachia gene insertions on the Glossinia chromosomes ( host DNA)

HORIZONTAL GENE TRANSFER AND WOLBACHIA

3 Wolbachia genes were found on the host DNA of

Glossinia m. morsitans in natural and lab populations

1. 16S rRNA (used in classifying and identifying bacterial species)

2. fbpA (ferric iron binding protein-encoding gene or fibronetin binding protein)

3. wsp (Wolbachia surface protein)

led to the identification of at least 2 horizontal gene transfer

events

52% of Wolbachia genome transferred in one event

and 47% of Wolbachia genome being transferred

in the other event.

Whole Genome Sequence of Glossinia m.morsitans

POSSIBILITIES AND HOPE

The HGT of Wolbachia genome can provide clues into the evolution and transfer of endosymbiont genes into multicellular organisms

aiding in the development of Wolbachia as a transport device to get desired genes into vectors such as the tsetse fly to stop the spread of African Trypanosomiasis and other diseases spread by insects.

DISEASES

disease produced by a filarial worm depends on the tissue locations preferred by adults and type of microfilariae

lymphatic filariasis disease is caused by the presence of

worms in the regional lymphatic vessels and by the host response to the worms and

worm products

OTHER FILARIAL NEMATODE INFECTIONS Elephantiasis of leg caused by chronic infection with

the filarial nematode Wuchereria bancrofti spread by a mosquito vector

Onchocerca volvulus is a filarial worm that is transmitted to humans by blackflies. Mature worms live in the subcutaneous tissues and

produce microfilariae that migrate through the skin and connective tissues.

do not move through the circulatory system 3-4 months after infection, form nodules on outer layer of

connective tissue which turns into calcifications

SUMMARY

HAT and AAT are serious problems in Africa and in North America someday, as climates change.

Insecticides are not environmentally responsible or sustainable, neither are baiting or releasing sterilized male tsetse flies.

Wolbachia has the potential to rid the world of this sickness and others, one fly at a time, one generation at a time.

Wouldn’t that be nice.

16S ribosomal RNA is a component of

prokaryotic ribosomes having 1,542 nucleotides

used in reconstructing phylogenies

multiple sequences of 16S rRNA can exist within a single bacterium

What is 16s rRNA?

16S RRNA (CONTINUED)

Carl R.Woese , an American microbiologist and biophysicist along with George E. Fox, a researcher at the University of Houston, were well known for their defining work in identifying a new domain in classifying organisms, Archaea.

by phylogenetic taxonomy of 16S rRNA stemming from their introduction of the lowest common ancestor (a progenote).

comparative analysis of ribosomal RNA which they believed was the earliest genetic resemblance to

life on Earth today.

PCR applications of 16S rRNA

highly conservative primer binding sites making PCR easier ( very few differences in primer sites for the gene)

Has hyper variable regions in its gene sequence making gene sequences making it a very species specific tool used to classify bacteria

Used in medical microbiology due to it being fast and inexpensive, compared to using phenotypes to identify bacteria

Originally used to classify bacteria now used to identify new species of bacteria

http://en.wikipedia.org

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