A Microbial Biorealm page on the genus Mycoplasma haemofelis
Higher order taxa
Bacteria; Firmicutes; Mollicutes; Mycoplasmatales; Mycoplasmataceae; Mycoplasma
Description and significance
Mycoplasma haemofelis was previously known as Eperythrozoon felis or Haemobartonella felis, and it was recognized as rickettsiae until the late 90’s (1). However, as more and more research was done on these specific bacteria, researchers realized that the classification for the bacteria had to be changed. These bacteria were parasitic, contained flagella, had small genome, and most importantly, lacked a cell wall. Therefore, researchers moved the bacteria to the class Mollicutes and the genus Mycoplasma (7). Mycoplasma haemofelis was first discovered by Flint and Moss in the United States in 1953, and they first described these bacteria as pathogens of the felines.
Mycoplasma haemofelis is a parasite that resides on the surface of red blood cell on felines, and it is about 0.5 um in diameter (1). In blood smears, the bacteria may be shaped as rings, rods or circles; sometimes they cluster together and form chains of bacteria on the surface of red blood cell (7). Further, there are three hemotropic Mycoplasmas that can infect felines: Mycoplasma haemofelis, Candidatus Mycoplasma haemominutum, and Candidatus Mycoplasma turicensis. As research has shown, multiple infections of the above pathogens will increase the severity of the clinical signs of Mycoplasma haemofelis infection (3). The prevalence of the bacteria has been estimated among domestic cats, and the infection rate appears to be 4.9 to 23.3 %; yet the actual prevalence in not calculated because the infections are not always detectable. Common diseases caused by Mycoplasma haemofelis are feline immunodeficiency virus (FIV), feline leukemia virus (FeLV), feline infectious peritonitis, and most importantly, feline infectious anemia (FIA) (1, 5). However, due to several metabolism pathways, the bacteria are difficult to cultivate in labs, and they often contaminate other cells (6). Details will be explained in the [Cell structure and Metabolism] section down below.
Mycoplasma haemofelis’ linear chromosome has an average of 1,199 kb with the standard deviation of 13.5 kb. The size fits well in the range or 580 to 1,400 kb for the genus Mycoplasma. 75 new genes were identified by running the sample with random sequencing, and these genes had never been reported or discovered for Mycoplasma haemofelis or other mycoplasma. Like all mycoplasma, which have a G+C (guanine-cytosine) percentage of below 50 %, Mycoplasma haemofelis has a G+C percentage of 38.5 % (2). One special feature of these bacteria is that the UGA codon is used for tryptophan instead of being a stop codon (6). Escherichia coli strain DH10B and the vector pBeloBAC11 can be used to create the bacterial artificial chromosome (BAC) library for Mycoplasma haemofelis. 430 never-before-seen genome survey sequences (GSS) were discovered by studying the BAC, and these sequences have now been added to the database of GenBank (2).
Mycoplasma haemofelis is unique compare to other mycoplasmas, and one of the reasons is that these bacteria contain the superoxide dismutase (SOD) gene while others do not. However, the SOD gene has not been fully studied and sequenced. Two other genes in particular interest many researchers because the enzyme activities of these genes were largely unknown in Mycoplasma haemofelis. One of the gene is related to purine biosynthesis, and the other one encode proteins that are closely related to inosine-5’-monophosphate dehydrogenase and guanosine-3’, 5’-monophosphate synthase (2).
Cell structure and metabolism
Mycoplasma haemofelis have filaments with special polar tips that help the bacteria attach to the hosts. These tips were formed by complex network of protein, designated adhesins, and adherence-accessory proteins. It is because of this tips that the bacteria are able to colonize on the surface eukaryotic cells (6).
Because of the small genome, Mycoplasma haemofelis is completely dependent on the host for nutrients and survival. With no cell wall components, Mycoplasma haemofelis has a unique plasma membrane that contains sterol, and the bacteria obtain the sterol from the host in the form of cholesterol. Further, Mycoplasma haemofelis must acquire most of the biosynthetic precursors from the host, for example, nucleotides, amino acids, cholesterol, and fatty acids. Consequently, this pathogen is hard to cultivate in a lab setting because of the bacteria’s highly demand for hosts, and yet it remain as one of the top contamination to other eukaryotic cells and tissue cultures (6). On the other hand, by being a parasite on the surface of red blood cell, Mycoplasma haemofelis can obtain the most nutrients from the host and grow in to large colonies. As studies have shown, although the bacteria are cell surface parasites, they do not penetrate the cell (7).
Most of the bacteria under the genus Mycoplasma are parasitic, such as Mycoplasma genitalium, Mycoplasma pneumoniae, and Mycoplasma haemofelis; therefore, they cannot survive on their own without hosts. Hence, they have little effect to the environment.
As mentioned before, Mycoplasma haemofelis is a feline parasite, and it can cause several diseases, such as, feline immunodeficiency virus (FIV), feline leukemia virus (FeLV), feline infectious peritonitis, and feline infectious anemia (FIA). General symptoms of infected felines includes anorexia, depression, lethargy, weakness, intermittent fever (40-42oC), weight loss, and in the end, death (1). The fever cycles because the number of bacteria varies, and the fever gets worse as the number of parasite increases in the peripheral blood. More symptoms will show up as the infection gets more severe and the bacteria may become regenerative. These symptoms include splenomegaly, icterus, anisocytosis, polychromasia, increase of reticulocytes or immune-mediated hemolytic anemia (1, 7).
Mycoplasma haemofelis can be transmitted vertically and horizontally. In vertical transmission, the kitten can be infected in the uterus, via parturition or nursing from the milk. On the other hand, what is known for horizontal transmission is that cats can get infected through infected blood or needles. The diagnosis of the parasites involves the careful studying of complete blood counts and peripheral blood smears. However, infection can go undetected if the sample is not obtained during parasitemic phase (1).
There are several possible treatments for Mycoplasma haemofelis, and some of them do perform a better job than others. Even though the bacteria react with the antibiotic tetracycline, this antibiotic has to be taken frequently and it may cause fever. On the other hand, by blocking protein synthesis, the antibiotic doxycycline does work better and is the preferred drug. Yet, side effect such as abdominal discomfort, esophagitis or anorexia may occur when the felines took doxycycline. Another possible drug is enrofloxacin, which only have to be taken once a day and have fewer side effects than doxycycline. Unfortunately, none of the drugs/antibiotics tested were able to completely eliminate the parasite, and all these drugs are capable of is control the infection (7).
Application to Biotechnology
Due to the nature of Mycoplasma haemofelis, it is very hard to cultivate this specific parasite or grow them into large quantities. Most of the researches have to collect the sample from infected felines instead of grown cultures. Hence, there is no current application of Mycoplasma haemofelis to biotechnology yet (1, 2, 5).
1. Relation between Ctenocephalides felis and Mycoplasma haemofelis
It is known that by feed the cats Ctenocephalides felis, they can be infected with another parasite – Dipylidium caninum. Thus, some researchers were wondering whether or not Mycoplasma haemofelis can be transmitted via Ctenocephalides felis, if C. felis is infected with M. haemofelis. The research began by feeding 2 felines infected fleas and flea by-product; however, the result was negative for Mycoplasma haemofelis after two months of waiting period. Thus, the researchers tried feeding another group of uninfected felines with a various amount of infected fleas and flea by-product. The end result was not the same as the researchers predicted. None of the cats tested positive for the DNA of Mycoplasma haemofelis, and no clinical symptoms of any sort were detected. Consequently, the ingestion of Ctenocephalides felis does not transmit Mycoplasma haemofelis (3).
2. Feline Immunodeficiency Virus Infection and Marbofloxacin
Two different experiments were done in this research. Researcher Tasker and colleagues conducted this research hoping to find out the relation between feline immunodeficiency virus (FIV) infection and Mycoplasma haemofelis infection, and the effectiveness of antibiotic marbofloxacin on Mycoplasma haemofelis. In the U.S., data has shown that FIV infected felines are more vulnerable to Mycoplasma haemofelis infection; however, other regions have little evidence to support this statement. In order to prove this statement, 12 FIV infected and uninfected cats were tested with Mycoplasma haemofelis. However, as the results showed, there was no significant relationship between FIV infection and Mycoplasma haemofelis infection (4).
For the second part of the research, Tasker treated another group of infected and uninfected cats with marbofloxacin in order to determine whether or not this antibiotic, which is a fluoroquinolone related to enrofloxacin, can cure Mycoplasma haemofelis infection. After being treated for nearly a month, the researchers noticed a significance drop of the parasites in infected cats, and the DNA of the parasite was also negative in most cases. Hence, marbofloxacin is an effective treatment for Mycoplasma haemofelis infection (4).
3. Transmission of Mycoplasma haemofelis
The purpose of this research was to find possible transmission; ticks, mice and saliva and feces of infected felines were all being tested to see if they can transmit Mycoplasma haemofelis. The end result for this particular research revealed that saliva and feces can be a way of transmission in the earlier state, but as time passed by, they would lose the ability to pass on the infection. On the other hand, ticks and mice could not cause the infection in cats because they could not carry a significant amount of the parasite (8).
. Haefner, M., Burke, T. J., Kitchell, B. E., Lamont, L. A., Schaeffer, D. J., Behr, M., and Messick, J. B.. “Identification of Haemobartonella Felis (Mycoplasma Haemofelis) in Captive Nondomestic Cats.” Journal of Zoo and Wildlife Medicine. 2003. Volume 34. p. 139-143. http://www.bioone.org/perlserv/?request=get-document&issn=1042-7260&volume=034&issue=02&page=0139
. Berent, L. M., and Messick, J. B.. “Physical Map and Genome Sequencing Survey of Mycoplasma haemofelis (Haemobartonella felis).” Infection and Immunity. June 2003. Volume 71. No. 6. p. 3657-3662. http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=155732
. Woods, J. E., Wisnewski, N., and Lappin, M. R.. “Attempted transmission of Candidatus Mycoplasma haemominutum and Mycoplasma haemofelis by feeding cats infected Ctenocephalides felis.” American Journal of Veterinary Research. 2006. Volume 67. p. 494-497.
. Tasker, Severine., Caney, S., Day, M. J., et al. “Effect of chronic FIV infection, and the efficacy of marbofloxacin treatment, on Mycoplasma haemofelis infection.” Veterinary Microbiology. Oct 2006. Volume 117. p. 169-179.
. Morais, H., Guimaraes, A. M. S., Vidotto, O., Baumann, A., Biondo, A. W., and Messick, J. B.. “Co-infection with Mycoplasma haemofelis and ‘Candidatus Mycoplasma haemominutum’ in three cats from Brazil.” Journal of Feline Medicine and Surgery. 2007. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WJC-4PCXXTJ-1&_user=4429&_coverDate=08%2F10%2F2007&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000059602&_version=1&_urlVersion=0&_userid=4429&md5=b975af76d212b50cfc498365f9d86197#
. Baseman, J. B., and Tully, J. G.. “Mycoplasmas: Sophisticated, Reemerging, and Brudened by Their Notoriety.” Emerging Infectious Diseases. 1997. Volume 3. No. 1. p. 21-31.
. Messick, J. B.. “New Perspectives about Hemotrophic mycoplasma (formerly, Haemobartonella and Eperythrozoon species) infections in dogs and cats.” The Veterinary Clinics Small Animal Practice. 2003. Volume 33. p. 1453-1465.
. Willi, B., Boretti, F. S., Meli, M. L., et al. “Real-time PCR investigation of potential vectors, reservoirs, and shedding patterns of feline hemotropic mycoplasmas.” Appl Environ Microbiol. Jun 2007. Volume 73. p. 3798-3802. http://aem.asm.org/cgi/content/full/73/12/3798
Edited by KLB