Lab 4 Flashcards
Apicomplexans I
What 4 organisms do we need to know for Apicomplexans 1?
Eimeria tenella, Sarcocystis spp, Toxoplasma gondii, Cryptosporidium parvum
Toxoplasma gondii causes what?
Toxoplasmosis
Cryptosporidium parvum causes what?
cryptosporidiosis
All Apicomplexans contain an apical complex that consists of 5 things:
polar ring, subpellicular tubules, conoid, rhoptries, micronemes
When does the apical complex disappear?
After host cell penetration
Apical complex plays a role in __________
host cell penetration
Most apicomplexans have ___________ reproduction
both sexual and asexual reproduction
Which kinds of life cycles are found in apicomplexans?
both direct and indirect
Schizogony-
(multiple fission) asexual reproduction in which multiple mitoses take place followed by simultaneous cytokinesis resulting in many daughter cells at once
Merogony-
(schizogony) multiple fission produces many daughter cells called merozoites
Merozoites-
daughter cells produced from merogony which will asexually reproduce more merozoites
Meront-
the cell that undergoes merogony. It will contain many merozoites.
Gametogony-
merozoites or trophozoites maturing to form gametocysts
Macrogametocyte-
will produce female gametes “macrogametes”
Microgametocyte-
will produce male gametes “microgametes” (only flagellated stage in this group)
Sprogony-
zygote undergoes multiple fission to produce sporozoites
sporozoites-
daughter cell produced during sporogony. An infective stage
zygote-
produced by fusion of macrogamete and microgamete
Spore-Oocyst-
the cystic form resulting from sporogony. Contains sporozoites, has resistant membrane secreted around it in some species and lacks the resistant membrane in others
An oocyst is NOT THE SAME THING AS A ________
Cyst
Syngamy-
fusion of male and female gametes to produce a zygote
Endopolygeny-
internal budding but no cytokinesis
The parasitic niche of Coccideans is…
the GI tract and associated organs (liver, kidney, blood)
Coccideans alternate between __________ reproduction
sexual and asexual
The three phases in the life cycle are:
Merogony, Gametogony, Sporogony
_________ occur within host cell
merogony and gametogony
__________ occur outside the host in soil or litter
sporogony
All apicomplexans in this lab are in the class ________
Coccidea
The infective stage of these organisms is the:
sporozoite
The sporozoite resides in very resistant spores called:
oocysts
Eimeria oocysts have ____ sporocysts containing ____ sporozoites each.
4
2
Isospora oocysts have ____ sporocysts containing ____ sporozoites each.
2
4
You cannot distinguish between Eimeria and Isospora oocysts until:
they are sporulated
Eimeria spp are economically important parasites in ________
domestic animals
Eimeria development within host is ________.
They are host specific/non-specific? and within host, are/are not tissue specific?
- intracellular
- specific
- are
Can immunity occur with Eimeria?
Yes, but if immunity develops, it is only partial
Eimeria tenella:
Host =
Niche =
Mechanism of Pathogenesis in host =
Chickens
GI tract
necrosis of cecal epithelium
Chickens of what age are most susceptible to Eimeria tenella?
young chickens
Is there a treatment for Eimeria tenella?
None once infection is established
What is added to commercial chicken feeds and why?
coccidostats to prevent infection with Eimeria tenella
Eimeria tenella infections in chickens are _______ (asexual reproduction does not continue indefinitely)
self limiting
If a chicken survives primary tenella infection, may have ________
partial immunity
Concurrent infections can occur with other Eimeria spp. In other words:
infection with one species actually seems to enhance infection with a second species
tenella transmission occurs from:
ingestion of sporozoite within sporulated oocysts in soil/litter
Upon tenella ingestion in chickens, sporulated oocysts release ______ into ______. These penetrate _______ to become ______
- sporozoites into small intestine
- epithelial cells of cecum
- trophozoites
tenella trophozoites in intestinal epithelium becomes a first generation _______, undergoing ________ to produce _________
- schizont (meront)
- schizogony (merogony, multiple fission)
- many daughter cells called “merozoites”
once merozoites have formed in epithelial cells, they are released into lumen when ______
the cell ruptures
First generation merozoites that have burst into the lumen will then __________
penetrate other epithelial cells
once first generation merozoites have penetrated new epithelial cells, they can choose between two paths in life:
- they can repeat the prosame process of multiple fission to produce a second generation of merozoites. (this can go on indefinitely, 3rd, 4th, etc generations)
- They can undergo gametogony, transforming into gamonts (gametocytes: macro and micro gametocytes)
Most gametocytes will become micro/macrogametes? But some will become ________gametocytes. These will then undergo ______ to produce ________
- macrogametes
- microgametes
- schizogony to produce many bi-flagellated microgametes
Fusion of a micro and macro gamete creates a _______, aka an __________
zygote aka an unsporulated oocyst
once tenella zygotes (unsporulated oocysts) get pooped out, they undergo _______ in the shit pile to form ___________
- sporogony (multiple fission)
- 4 sporocysts, each with 2 sporozoites. All 4 are contained within the sporulated oocyst
tenella sporozoites are _____ shaped
banana or rod shaped
the rounded up small single-cell uninuclear form of tenella sporozoite becomes this when it penetrates an epithelial cell is called a _______
Trophozoite
tenella trophozoite can easily be distinguished from the nucleus of the cell it inhabits as a ________
small nucleus (much smaller than cell nucleus) surrounded by a clear halo
once a tenella trophozoite undergoes schizogony, it is called a _______. This epithelial cell is filled with _________
- schizont/meront
- many small nuclei scattered in the cytoplasm
Within a tenella meront, each small nucleus becomes visble as a spindle shaped organism called a ________. It is also possible to see this organism free in the lumen if what has just happened?
- merozoite.
- if the cell has just ruptured
The asexual portion of the tenella life cycle involves _______, and the sexual portion involves ___________.
- forming another generation of merozoites
- transforming into a gametocyte
Where does the tenella macrogametocyte reside and what does it look like?
- resides inside the cecal epithelial cell (crowds the epithelial cell nucleus to one side)
- has a large central nucleus, large cytoplasmic granules, tends to be found in groups of cells
the tenella microgametocyte resides _______, and following many rounds of multiple fission will be a big cell full of _________, which look like ________
- within cecal epithelial cells
- many microgametes
- tiny slender biflagellates
When a microgamete fertilizes a macrogamete, the cell is called a ________. It ruptures from the epithelial cell and is shit out.
Oocyst/zygote
Is an oocyst infective?
No, it must undergo sporulation to be infective
How long does it take for sporulation to occur in a tenella oocyst in the shit pile?
within 48 hours
When looking at an Eimeria slide at 5.5 days post infection, you will see:
meronts with merozoites
When looking at an Eimeria slide at 7 days post infection, you will see:
Oocyst taking up basically all of the room in the host cell
1 Eimeria oocyst produces ____ sporozoites, each of which can produce ________ merozoites, each of which can be fertilized to become another oocyst.
8
millions
3 ways Eimeria infection will not take hold in a chicken:
- organism enters epithelial cell about to be sloughed off. (epithelial cells get sloughed every 3 days)
- organism gets shit out before it can infect another cell
- host immune response can get some of the merozoites as they leave epithelial cells
The family Sarcocystidae contains which 2 organisms?
Toxoplasma gondii and Sarcocystis spp
Sarcocystidae have a ________ life cycle, consisting of _______ development in intermediate host and ________ development in definitive host
- Heteroxenous
- asexual
- sexual
Sarcocystidae life cycle takes place in both ______ and _______
intestines and tissues (extra intestinal)
Sarcocystidae oocysts contain __ sporocysts each with ___ sporozoites.
2
4
Transmission of Sarcocystidae involves ingestion of ________ or _______
sporozoites within sporulated oocysts or tissue containing cysts with bradyzoites
Tachyzoites-
merozoites formed by multiple fission (endodyogeny) of sporozoites
bradyzoites-
merozoites formed in tissue cysts in extra intestinal sites
bradycysts-
same thing as a tissue cyst; also called a pseudocyst or zoitocyst
Sarcocystidae sexual reproduction occurs in ___________ and produces ______. Asexual reproduction occurs in _______ and results in ________
- intestine
- oocysts
- tissues
- tachyzoites and bradyzoites
Toxoplasma gondii is an obligate _______
intracellular parasite
Toxoplasma gondii’s only definitive host is ______, but it has many intermediate hosts, including humans.
cats (domestic and wild)
Toxoplasma can be transmitted to fetus _____
transplacentally
Is there an intestinal stage for Toxoplasma in intermediate host?
NO, penetrates intestine and is engulfed by macrophages for distribution in body
Why are Toxoplasma not killed when ingested by macrophages?
It prevents the macrophage lysosomes from fusing with the vacuole it resides in.
Toxoplasma sporozoite in macrophage undergoes _____ to produce ______. The macrophage then ruptures, and they invade other tissues, especially: (5 places)
- schizogony
- tachyzoites
- striated muscle, retina, brain, liver, lymph nodes (any nucleated cell)
Which form of toxoplama crosses placenta?
Tachyzoites
Upon entrance into new tissues in the body, tachyzoites undergo ______, continuing the asexual cycle until what happens?
- schizogony
- host immune response eventually limits the parasite’s asexual reproduction
When Intermediate host starts fucking with the tachyzoites of Toxoplasma gondii, some will _________ and accumulate into ______ that lay dormant for a very long time.
- differentiate into bradyzoites
- pseudocysts/tissue cysts
Host immune system will keep bradyzoite pseudocysts ________
latent/inactive. (so there is no inflammatory response
Cats, our toxoplasma definitive host, can get the parasite in 2 ways:
- ingesting sporulated oocyst
2. eating tissue infected with pseudocysts
If a cat ingests an oocyst, what happens?
If a cat ingests a pseudocyst, what happens?
- sporozoites are released and invade intestinal epithelium
- bradyzoites are released and invade intestinal epithelial cells
within 3-5 days of toxoplasma infection in cats, what begins to happen?
some merozoites begin to undergo sexual reproduction (gametogony)
Just like Eimeria tenella, Toxoplasma gondii sporulation occurs _________
outside the host in the shit pile
We know cats are definitive host, and many other mammals including humans are intermediate hosts, but can cats also be intermediate host?
Yes they can
Although typically asymptomatic, what symptoms may occur in humans infected with Toxoplasma gondii?
Enlargement of lymph nodes (especially cervical lymph nodes), low grade fever
Human immunity to Toxoplasma is ________. If a pseudocyst ruptures, a severe immune reaction can occur, killing all the bradyzoites, the only downsides to this are:
- complete
- if this occurs in the brain or retina, encephalitis or blindness can occur, respectively
Adults can be at risk for severe disease or fatality from Toxoplasma gondii if they _____________ or have _______
- receive an infected organ transplant, especially hearts
- AIDS
When congenital toxoplasmosis occurs in humans, the mother can have no clinical signs, but the fetal infection can vary from ________ to _____________. Fetal damage is most acute if infection occurs ________
- asymptomatic to severe developmental damage
- in the first trimester
Sarcocystis spp has an _______ intermediate host and a _______ definitive host.
- herbivorous
- carnivorous
Infection of sarcocystis definitive host occurs by ________
ingestion of bradyzoites in meat
Sarcocystis spp bradyzoites will transform into _______ in the _______, then _______ and undergo _________
- merozoites
- intestine
- invade epithelial cells
- gametogony
Sarcocystis spp oocytes are formed only in ______
definitive hosts
Sarcocystis spp differ from the other apicomplexans in that oocysts sporulate in ______ and then ________
- intestine
- rupture, releasing sporocysts containing sporozoites that pass out in feces
If sarcocystis spp sporocysts are ingested by an intermediate host, they burst in intestine and undergo the same process as ________
-Toxoplasma in humans (shizogony–tachyzoites–bradyzoites–cysts
Sarcocystis spp cysts in intermediate host are called _______, not pseudocysts
sarcocysts or zoitocysts
sarcocysts will typically form in _________
Striated and cardiac muscle, and sometimes the brain
The only Sarcocystis spp form infective for definitive hosts is ________
bradyzoites
Cryptosporidium are parasites of what two body areas?
intestinal and respiratory epithelium
Cryptosporidium parvum is an opportunistic parasite of _______, especially _________. It is very common in ______ patients.
- humans
- young children
- AIDS
When presented with chronic diarrhea, _________ is the most likely culprit
Cryptosporidium parvum
Cryptosporidium parvum undergoes ______(3 things) within microvilli of epithelial cells in GI tract
Schizogony, gametogony, sporogony
Cryptosporidium parvum is passed in feces as _______
very small round oocysts
Cryptosporidium oocysts have no ________, just 4 slender ________
- sporocysts
- sporozoites
_______ Crypto. oocysts pass out with feces. ________ crypto. oocysts can rupture in lumen of gut and cause auto infection of infected host
- thick walled
- thin walled
Cryptosporidium parvum:
- only about _______ sporulated oocysts are required to infect host
- oocysts survive a long time in water, but ____ will kill them
- most common source of infection is from ______
- 30-100
- drying out
- contaminated water
Zoonosis-
can spread from animals to man and vice versa
How does Cryptosporidium parvum evade host defenses and drug treatments?
it coats itself in host cell derived membrane when it attaches to GI epithelium. Although it is technically not intracellular, it has wrapped itself in the host cell membrane, which makes it untreatable
Cryp. parv. is NOT _________, it has simply wrapped itself in the host cell membrane next to the host cell
intracellular
