Cryptosporidium parvum: Difference between revisions

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==Pathology==
==Pathology==
How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.
C. parvum is responsible for intestinal, tracheal, and pulmonary cryptosporidiosis.  Often transmissions occur by the ingestion of contaminated public water supplies, making transmissions common in places such as water parks and public pools.  The most common symptom is severe diarrhea, but in cases of pulmonary and tracheal cryptosporidiosis coughing and fever can also be seen (9).  For the most part, the diarrhea is self limiting.  However, immuno-compromised individuals can develop uncontrollable diarrhea leading to severe dehydration that is potentially fatal (2). 
 
C. parvum is cystforming apicomplexans which mean it forms oocysts as part of its life cycle.  Oocysts are highly resistant to environmental stresses.  It is resistant to conventional chlorine treatment of the community water supplies which makes prevention of cryptosporidiosis difficult.  The oocysts are shed from the infected host in their feces, and the feces can contaminate both water and food.  The disease is transmitted through the feces oral route which means that the disease is obtained through the ingestion of contaminated water or food.  Researchers have been unable to successfully culture the parasite continuously in the lab which makes the studying of this organism difficult.  Also, the parasite cannot be genetically manipulated causing further limitations in the studies of the organism.  (2)
 
Another important aspect of the pathology of C. parvum has to due with its cell divisions.  Apicomplexans undergo many different types of cell division. The life cycle consists of an intracellular, asexual phase of multiplication followed by the differentiation of gametes, fertilization, meiosis and the release of infectious oocysts in the gut lumen (6).  One of the unique aspects of their life cycle is merogony.  During this stage of the lifecycle, the parasite replicates its DNA several hundred times before splitting into hundreds of daughters cells simultaneously. This process is important to apicomplexan pathogenesis, and it means that large number of parasites can be generated in just one cell cycle (3). 
 
Some researches have been done using antibodies as a possible treatment.  Passive antibody therapy has been looked into as a possible treatment for cryptosporidiosis since antimicrobial drugs in immuno-compromised hosts are ineffective.  And AIDS patients are extremely vulnerable to this disease.  One of the benefits of the antibody therapy is that for cryptosporidiosis, the antigens can be taken orally unlike other disease where only a systemic administration is required (4).


==Application to Biotechnology==
==Application to Biotechnology==

Revision as of 05:25, 29 August 2007

A Microbial Biorealm page on the genus Cryptosporidium parvum

Classification

Higher order taxa

Eukaryota; Alveolata; Apicomplexa; Coccidia; Eucoccidiorida; Eimeriorina; Cryptosporidiidae; Cryptosporidium; Cryptosporidium parvum

Species

NCBI: Taxonomy

Cryptosporidium parvum

Description and significance

Cryptosporidium parvum is part of the phylum Apicomplexa which contains many important parasites such as Toxoplasma, Plasmodium, Babesia, Cyclospora, Isopora, and Eimeria. C. parvum is an eukaryotic intracellular pathogen that infects both humans and livestock causing the disease cryptosporidiosis (2). The parasite is a serious global health concern. It is especially a problem in underdeveloped regions of the world where sanitation is an issue (6). This parasite is also particularly dangerous to children and immuno-deficient patients. Transmission is common through ingestion of contaminated water sources. The disease has the potential to infect on a large scale. In 1993, 400,000 people in Milwaukee were ill from drinking water contaminated with this parasite (7). Important epidemiological studies have been done on the species. However, while extensive researches have been done on this particular parasite, no known cure is currently available for cryptosporidiosis (2). Ever since the Milwaukee incident, extra consideration has been given to control and prevent cryptosporidiosis outbreak (7).

Cryptosporidium parvum and Cryptosporidium hominis are two closely related pathogens. They are among the 15 species in genus Cryptosporidium that cause intestinal diseases in human and animals. C. parvum and C. hominis were previously known as C. parvum genotype 1 and C. parvum genotype 2, respectively. However, it is now understood that the two species have different transmission cycles and invade a different range of hosts. (8) The genomic sequences of C. hominis and C. parvum show that they only have 3-5% divergence and no large insertions, deletions or rearrangement. The similarity between the two suggests that their phenotypic differences are caused by polymorphism in coding regions and differences in gene regulation (1).

Genome structure

The complete genome of C. parvum has been sequenced and compared to other apicomplexans. The information below is obtained from the shotgun sequencing of the Iowa "type II" isolate of C. parvum. C. parvum's genome contains eight linear chromosomes with a total of 9.1Mb of DNA sequence. Its genome is relatively compact when compared to the genome of Plasmodium falciparum with 23 Mb of sequence in 14 chromosomes. C. parvum's genome has shorter intergenic regions, fewer introns, and less genes which contributes to its compactness (2). The sub-telomeric regions of the C. parvum genome do not have the clusters of large antigenically diverse protein families that are found in Plasmodium (5). It is estimated that C. parvum contains 3807 protein encoding genes, much less than the estimated 5300 genes of Plasmodium. This is due to the absences apicoplast and mitochondrial genome and having fewer genes encoding for metabolic functions and variant surface proteins. The breakdowns of the genes are as follow. The mean gene length excluding introns is 1795bp, the percent of coding DNA, 75.3%, the percent of genes with introns, 5%, the mean length of intergenic regions, 566bp, the gene density, 2382 bp per gene. And there is a 30% GC content in the genome, and 23.9% GC content in the intergenic regions. There are 45 tRNA genes, six 5S rRNA genes, and five 5.8S, 18S, and 28S rRNA units (2).

Cell structure and metabolism

Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.

Ecology

Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.

Pathology

C. parvum is responsible for intestinal, tracheal, and pulmonary cryptosporidiosis. Often transmissions occur by the ingestion of contaminated public water supplies, making transmissions common in places such as water parks and public pools. The most common symptom is severe diarrhea, but in cases of pulmonary and tracheal cryptosporidiosis coughing and fever can also be seen (9). For the most part, the diarrhea is self limiting. However, immuno-compromised individuals can develop uncontrollable diarrhea leading to severe dehydration that is potentially fatal (2).

C. parvum is cystforming apicomplexans which mean it forms oocysts as part of its life cycle. Oocysts are highly resistant to environmental stresses. It is resistant to conventional chlorine treatment of the community water supplies which makes prevention of cryptosporidiosis difficult. The oocysts are shed from the infected host in their feces, and the feces can contaminate both water and food. The disease is transmitted through the feces oral route which means that the disease is obtained through the ingestion of contaminated water or food. Researchers have been unable to successfully culture the parasite continuously in the lab which makes the studying of this organism difficult. Also, the parasite cannot be genetically manipulated causing further limitations in the studies of the organism. (2)

Another important aspect of the pathology of C. parvum has to due with its cell divisions. Apicomplexans undergo many different types of cell division. The life cycle consists of an intracellular, asexual phase of multiplication followed by the differentiation of gametes, fertilization, meiosis and the release of infectious oocysts in the gut lumen (6). One of the unique aspects of their life cycle is merogony. During this stage of the lifecycle, the parasite replicates its DNA several hundred times before splitting into hundreds of daughters cells simultaneously. This process is important to apicomplexan pathogenesis, and it means that large number of parasites can be generated in just one cell cycle (3).

Some researches have been done using antibodies as a possible treatment. Passive antibody therapy has been looked into as a possible treatment for cryptosporidiosis since antimicrobial drugs in immuno-compromised hosts are ineffective. And AIDS patients are extremely vulnerable to this disease. One of the benefits of the antibody therapy is that for cryptosporidiosis, the antigens can be taken orally unlike other disease where only a systemic administration is required (4).

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

Enter summaries of the most recent research here--at least three required

References

Pain, A., Crossman, L., and Parkhill, J. “Comparative Apicomplexan genomics”. Nature Reviews Microbiology. 2005. Volume 3. p. 454-455. http://www.nature.com/nrmicro/journal/v3/n6/full/nrmicro1174_fs.html

Abrahamsen, M., Templeton, T., Enomoto, S., Abrahante, J., Zhu, G., Lancto, C., Deng, M., Liu, C., Widmer, G., Tzipori, S., Buck, G., Xu, P., Bankier, A., Dear, P., Konfortov, B., Spriggs, H., Lyer, L., Anantharaman, V., Aravind, L., and Kapur, V. “Complete Genome Sequence of the Apicomplexan, Cryptosporidium parvum”. Science. 2004. Volume 304. p. 441-445. http://www.sciencemag.org/cgi/content/full/304/5669/441

Rider, S., Cai, X., Sullivan, W., Smith, A., Radke, J., White, M., and Zhu, G. “The Protozoan Parasite Cryptosporidium parvum Possesses Two Functionally and Evolutionarily Divergent Replication Protein A Large Subunits”. J. Biol. Chem. 2005. Volume 280. p. 31460-31469. http://www.jbc.org/cgi/content/full/280/36/31460

Casadevall, A., Dadachova, E., Pirofski, L. “Passive Antibody Therapy for Infectious Diseases”. Nature Reviews Microbiology. 2004. Volume 2. p. 695-703 http://www.nature.com/nrmicro/journal/v2/n9/full/nrmicro974_fs.html

Pain, A., Crossman, L., Sebaihia, M., Cerdeño-Tárraga, A., and Parkhill, J. “Strength in Diversity”. Nature Reviews Microbiology. 2004. Volume 2. p. 358-359. http://www.nature.com/nrmicro/journal/v2/n5/full/nrmicro889_fs.html

Widmer, G., Yang, Y., Bonilla, R., Tanriverdi, S., and Ciociola, K. “Preferential infection of dividing cells by Cryptosporidium parvum”. Parasitology. 2006. Volume 133. p. 131-138. http://journals.cambridge.org/action/displayFulltext?type=6&fid=454979&jid=&volumeId=&issueId=02&aid=454977&fulltextType=RA&fileId=S0031182006000151

“Cryptosporidiosis Control and Prevention”. Center for Disease Control and Prevention. http://www.cdc.gov/ncidod/dpd/parasites/cryptosporidiosis/crypto_control_prevent.htm

Bandyopadhyay, K., Kella, K., Moura, I., Cristina, M., Carollo, C., Graczyk, T., Slemenda, S., ohnston, S., Silva, A. “A rapid microsphere assay for identification of Cryptosporidium hominis and Cryptosporidium parvum in stool and environmental samples”. 2007. Published online ahead of print. http://jcm.asm.org/cgi/reprint/JCM.00138-07v1?view=long&pmid=17652477

"Foodborne Pathogenic Microorganisms and Natural Toxins Handbook, Cryptosporidium parvum”. U.S. Food and Drug Administration. http://www.cfsan.fda.gov/~mow/chap24.html

Guisar R., Herrera, M., Bandala, E., Garcia, J., and Corona-Vasquez, B. “Inactivation of waterborne pathogens using solar photocatalysis”. Journal of Advanced Oxidation Technologies. 2007. Volume 10. p. 435-438. http://portal.isiknowledge.com/portal.cgi?DestApp=WOS&Func=Frame


Edited by student of Rachel Larsen Angela Wang