Assays to diagnose infectious disease must be: specific (no false positives or cross reactivity); and sensitive (able to identify even a single cell). Indirect assays detect antibodies, which are evidence of past and perhaps prsent infection. Direct assays detect the parasite itself. Technique Direct? Overview Xenodiangosis Direct Immunofluorescence Indirect DNA Assay Direct PCR detection of [...]

Multidrug resistant protein (MDR) is a ~170 kDa P-glycoprotein that confers drug resistance. It is overproduced and targeted to the vacuole membrane where it inserts using 12 transmembrane domains to form a pore. It can bind many classes of drugs and pump them out using its own ATPase domain to drive the reaction.

Whereby two daughter cells form inside the mother cell and eventually take it over.

Microscopic detection of amastigotes (LD bodies) in stained smears made from the edges of the ulcer. Culturingparasites from the lesion canalso be used in diagnosis. Old World Cutaneous Leishmaniasis Starts as a papule that runs an acute course (1-3 weeks) with early ulceration and a surrounding zone of inflammation, that usually heals in two months [...]

LtREL 1 Leishmania tarentolae RNA Editing Ligase 1 CBP Calmodulin Binding Protein TEV Tobacco Etch Virus Protease Protein A Binds IgG (sepharose conjugated)

There are ~100 different known guide RNAs (aka gRNAs). There is one guide RNA per minicircle species, and ~10,000 minicircles per kDNA network. There are multiple copies of each minicircle species. There are also maxicircle guide RNAs. Component Overview Anchor Region Hybridizes to the mRNA. Guide RNA hybridizes to mRNA at the anchor. Guiding Region [...]

Cryptogene A gene whose transcript is edited. Guide RNA (aka gRNA) A short 3′-uridylated RNA that can form a perfect duplex (except for the oligo[u] tail) with a stretch of mature edited mRNA. G-U base pairing is allowed. Anchor Duplex The RNA duplex formed by hybridization of the 5′ end of the gRNA and the [...]

Entamoeba histolytica is the third parasitic killer worldwide. Despite this, it infects many more than it kills. It has a worldwide distribution and lacks a vector, instead transmitting as cysts via fecal-oral route. Poor sanitation leads to contaminated water and a high incidence of this disease. It is diagnosed via microscopy, ELISA and/or PCR. Entamoeba [...]

What Is Toxoplasma? Toxoplasma gondii is an obligate intracellular parasite that grows and divides inside a host cell and has no extracellular lifecycle. Toxoplasma gondii‘s importance rests upon its worldwide distribution and ability to infect almost any mammalian or avian cell. Felines (where its sexual stage occurs) are Toxoplasma gondii‘s definitive host; it lacks a [...]

What Is Tetraspanin? Tetraspanins (aka TSPs) are eukaryotic membrane proteins involved in proliferation, adhesion, migration, fusion and signal transduction. Tetraspanin proteins contain: four transmembrane domains; a short extracellular loop (EC1); a longer extracellular loop (EC2) and short N-terminal and C-terminal tails. More Information Extracellular Domain 2 (EC2) contains: a constant region with three α-helices; and [...]

Infects Humans Organism Disease Plasmodium Malaria Toxoplasma Toxoplasmosis Cryptosporidium Cryptosporidiosis Infects Animals Organism Disease Eimeria Coccidiosis Theileria Theileriosis Babesia Babesiosis Neospora Neosporosis Apicomplexans Have Three Genomes Genome Overview Mitochondrial 6 kb tandem repeat; CO1, COII, Cyb; Fragmented rRNA Nuclear 11 chromosomes; 80 x 106 bp haploid; Map unit 150-300 kb Apicoplast 35 kb genome; Plastid [...]

Metronidazole is the main treatment for T. vaginalis. Its derivative tinidazole is so similar that a strain resistant to one drug is oft resistant to the other. In the T. vaginalis hydrogenosome, these drugs are activated when ferredoxin transfers an electron to metronidazole’s NO2 group and a lethal free radical forms. Sensitive parasites lacking hydrogenosomes [...]

Metronidazole is marketed as Flagyl and is chemically 1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole. It selectively kills anaerobic cells. The only other approved drug for treatment of trichiomoniasis is tinidazole; a strain resistant to one drug is oft resistant to the other. In Trichomonas vaginalis it is activated in the hydrogenosome by ferredoxin; in Entamoeba hystolytica and Giardia lamblia it [...]

Mammalian galectins bind carbohydrates, preferring poly-N-acetyl lactosamine (Galβ1→4GlcNAcβ1). The three structural groups are: Proto Galectin Galectin-1,2,5,7,10. Cross-link homologous carbohydrate ligands. Chimera Galectin Galectin-3. Cross-links carbohydrate and non-carbohydrate ligands. Tandem Repeat Galectin Galectin-4,6,8,9. Cross-link two distinct carbohydrate ligands.

What Is Trichomonas vaginalis? Trichomonas vaginalis is the most common sexually-transmitted protozoan parasite. It is an extracellular parasite, a facultative anaerobe and lacks mitochondria (it is amitochondriate) and peroxisomes. Trichomonas vaginalis has a unique organelle called the hydrogenosome. It resides in the urogenital tract and is transmitted via sexual intercourse. It lacks a cyst stage, [...]

What Is A Hydrogenosome? Hydrogenosomes metabolize carbohydrates into ATP and H2. Metabolism in the hydrogenosome is similar to anaerobic bacteria (via enzymes including PFO and ferredoxin) and mitochondria (via Krebs cycle enzymes that convert acetyl CoA into acetate and succinyl CoA which is then converted to succinate and ATP). A Common Ancestor? Mitochondria and hydrogenosomes [...]

Apicoplasts Are Organelles & Have Genomes The apicoplast (aka plastid) is an organelle found exclusively in the apicomplexan phylum. The apicoplast has a 35kb genome and is surrounded by 4 membranes. Although its genome can be isolated and sequenced, the apicoplast itself cannot be isolated. The apicoplast is also known as a plastid, as drugs [...]

Key Points on Trypanosomes’ Flagellum Gross flagellum structure same in BSF and PCF. There are differences, many of which are not understood. Flagellum is attached to cell body along its length. This is mediated by well-organized desmosome-like juctions between the membranes of the flagella and parasite. Direction of motility is toward the flagellum tip. Thisis [...]

Kala Azar Kala Azar (aka Black Fever) has existed in India and China for centuries. Kala Azar was considered to be a communicable malaria-like disease that showed relapses, emaciation, as well as enlargement of the liver and spleen, and spread slowly acrossthe continents along the trade routes. Parasite Discovery In 1900, Scottish Army doctor William [...]

Vector Horsefly. However, Trypanosoma evansi has no lifecycle in its vector. Transmission Life Cycle Stage Overview Disease Causes Surra in horses and castle. Stage Overview Detection Technique Overview

Vector Tsetse fly. Transmission Reservoir Wild animals Life Cycle Stage Overview Disease Causes Nagana in cattle. Stage Overview Detection Technique Overview

Discovery Overview Rhodesian Trypanosome In 1910, J. W. Stephens of the Liverpool School of Tropical Medicine discovered a new species of trypanosomes: it was from a Sleeping Sickness patient who acquird the disease in 1909 in Rhodesia. Trypanosoma gambiense and its vector Glossina palpalis do not exist in Rhodesia. The Rhodesian Sleeping Sickness was more [...]

Discovery Overview Sleeping Sickness Human Sleeping Sickness was observed by Arab doctors as early as 1375. In 1702, English naval surgeon John Atkins described sleepy distemper in Africans living along the Guinea Coast. In 1803, physician Thomas Winterbottom worked in the Sierra Leone colony and published an account of African lethargy. Winterbottom recognized a telltale [...]

Discovery Overview Cattle Decimation In the early 1890s, British colonial farmers in Zululand saw their European cattle breed (Nebu) decimated by a wasting disease called Nagana, the Zulu word for depression. The native cattle breed (N’Dama) was unaffected by Nagana. Identifying Parasite In 1894, Bruce was sent to investigate Nagana. He examined blood from diseased [...]

Discovery Overview First Sightings In 1841, G. Valentinin Berne of Switzerland examined trout blood and saw a protozoan propelled by an undulating membrane. This was a trypanosome. In 1843, David Gruby of Paris discovered a similar organism in frog blood and called it Trypanosoma sanguinis. Its etymology is: the Greek word trypano, meaning auger- or [...]

Discovery Overview Surra Disease In 1880, Griffith Evans, an English veterinarian in Punjab, India, found trypanosomes in the blood of horses, mules and camels suffering from a fatal wasting disease called surra (aka African Trypanosomiasis today). Inoculating healthy animals with trypanosome-infected blood produced surra; Evans was convinced the trypanosome was a parasite. In 1899, another [...]

Agent Trypanosoma rangeli is a protozoan parasite morphologically similar to T. cruzi and with an overlapping geographical distribution. T. rangeli infects humans and other animals but does not have pathogenic activity. However it is devastating to its insect vector R. prolixus. Vector Transmitted by the Reduviid (aka kissing bug) genera Rhodnius prolixus which resides in [...]

First described in 1877, xenodiagnosis is a direct method of diagnosing whether a patient is infected with a particular zoonose. This method is highly accurate compared to direct microscopy of a patient’s blood. As few as 10 Trypanasoma cruzi protozoa may be present per 1mL of blood, though only 1µL can be mounted and viewed [...]

Intracellular Bacteria Mycobacterium species; Listeria monocytogenes. Intracellular Fungi Pneumocystis carinii; Candida albicans. Intracellular Parasites Leishmania spp.. Viruses All viruses are intracellular pathogens. For example, herpes.

Anthroponosis Disease with humans as only vertebrate hosts. Zoonosis Disease transmitted among wild animals (reservoir hosts) and humans. Reservoir Host Wild animal that maintains infection in nature. Procyclic Related to the beginning of the parasite’s life cycle. Metacyclic Related to the infective stage of the parasite’s life cycle. VSG Variable surface glycoprotein ESAG Expression site [...]

Vector Sandflies are pool feeders — they prick their victim and suck up the resulting pool of blood. They are infected upon ingesting infected macrophages. Transmission Life Cycle Amastigote Macrophage Amastigotes are within the macrophages. Ingestion Upon ingestion by the sandfly, amastigotes transform into promastigotes. Promastigote Gut The promastigotes in the gut of the female [...]

Helicobacter pylori secretes urease to maintain a basic/neutral environment. Lophotrichous tufted flagella, powered by a proton gradient, give it motility. Helicobacter pylori is extracellular and does not need to be intracellular to replicate. They have a tuft at one end, and this is mediated by that they are encased in a membrane. The structure of [...]

How Can Resistance Occur? Underproduction of proteins required for drug activation. Underproduction of a membrane protein that is necessary for uptake of the drug (methotrexate resistance in Leishmania). Overproduction of the target enzyme resulting from DNA amplification: Dihydrofolate reductase-thymidylate synthetase (DHFR-TS) overproduction leading to methotrexate resistance. Mutation in a cellular protein that results in decreased [...]

Spirochetes are helically shaped, either resembling a corkscrew or a flat wave. Spirochetes have hidden flagella and tremendous antigenic variation, making them potentially potent pathogens. Spirochetes thrive in blood, saliva and other nutrient-rich environment; they are susceptible to (and avoid via chemotaxis) H2O2 and other free radicals. Interestingly, Borrelia species do not have LPS in [...]

Competition assay tests virulence factor. Mix mutant and WT strains of bacteria. If mutant has defect in virulence, this will be detected by examining ratio of mutant:WT at assay endpoint.

Virulence factors are cellular properties which promote pathogenesis. Without these virulence factors, pathogenesis is attenuated or eliminated. These virulence factors can be: Factor Overview Adherence Colonization and contact.. Invasins Tissue and cell invasion. Toxins Motility and chemotaxis. Nutrition Compete for nutrients. Evasion Evasion and suppression of immune response.

Name Organism Activity Anthrax Toxin Bacillus anthracis Edema Factor (EF) is an adenylatecyclase that causes increased levels in intracellular cyclic AMP in phagocytes and formation of ion-permeable pores in membranes (hemolysis). Adenylate cyclase toxin Bordetella pertussis Acts locally to increase levels of cyclic AMP in phagocytes and formation of ion-permeable pores in membranes (hemolysis). Cholera [...]

Botulism is a Category A bioweapon. It has a highly stable spore capable of surviving autoclaving, produces a potent toxin (175ng kills a 150lb man), and there are no effective treatments after toxin production. It has good medical applications, though, such as Botox. In 1989, FDA approved the use of BoNT-A (BOTOX, Allergan, Inc.) for [...]

There are two ways that toxins are released into the environment. Some cells will secrete toxins while other cells will release toxins upon cell lysis. Exotoxins are secreted by the cell while endotoxins are released upon cell lysis. Endotoxins are usually a lipopolysaccharide or a cell wall protein. There are three ways for exotoxins or [...]

Trypanosoma cruzi (aka Schizotrypanum cruzi) is a protozoan parasite and the causative agent of Chagas Disease. Chagas Disease is prevalent in South and Central America, having infected 15-20 million people and with over 100 million people at risk. Up to 60% of the population is serologically positive for Trypanosoma cruzi in some endemic areas. Once [...]

Foodborne illnesses can be caused by microbes two different ways: poisoning and infection. Food poisoning results from ingesting a bacterial exotoxin. Onset of food poisoning symptoms is rapid. Food infection results from ingesting a food contaminated with bacteria. Onset of food infection symptoms is relatively slow (sometimes several days).

T. brucei gambiense T. brucei rhodesiense T. brucei brucei Distribution West Africa East Africa Vector Glossina palpalis G. morsitans, palpides. G. palpalis, fuscipes, tachinoides Disease Chronic (mo’s-y’rs) Acute (w’ks-mo’s) Parasitemia Low High CNS Spread Late Early Host Human Humans & Game Cattle & Game HDL Rxn? No No Yes Vector The tsetse fly, encompassing all [...]

Salmonella spp. S. thyphimurium is usual cause of human salmonellosis Gram negative, motile rods, non-sporeforming common in the intestinal tract of fowl produce enteroendotoxins Salmonella spp. found in poultry, eggs, cantaloupe, tomatoes, cilantro, alfalfa sprouts, clover sprouts, mung-bean sprouts, orange juice S. thyphimurium approx. 10,000 cells are sufficient to cause an infection salmonellosis arises after [...]

Step Overview Isolate Isolate chromosome from a homogeneous population. Digest Digest into 150kb sequence fragments. Clone Clone fragments into bacterial artificial chromosomes (BACs). Transform Transform BACs into recipients. Screen Screen for transformed colonies (selective media, like Xgal or CAM). Sequence Sequence the inserts. Assemble Assemble genome based on overlapping sequences. Annotate Genome annotation using BLAST [...]

Colony Form Description Pinpoint Smaller than 1 mm. Circular A circle larger than 1 mm. Irregular A non-circular shape. Filamentous Resembling a bunch of strings. Colony Elevation Cushion Raised Flat Raised Center Colony Surface Smooth Smooth colony surface. Rough Rough colony surface. Ringed A colony surface with rings. Colony Texture Amorphous A typical textureless colony. [...]