How does mycobacterium leprae reproduce

The G-C content of the genome is The genomes for M. The similarity of the pseudogenes in M. This is an example of reductive evolution. It is estimated that M. The loss of genes in metabolic pathways such as energy metabolism, limiting the carbon sources M leprae can use, and holes in respiration pathways help to explain why M leprae can not be cultured in a laboratory and has only been shown to infect humans, the footpads of mice, and armadillos.

From a thorough examination of the genome of M. Compared to the genome of M. This means that M leprae can not synthesize the vitamin or methionine, an amino acid, and instead has to be taken from the environment Wheeler To test the presence of methionine and vitamin B12 were enough for M leprae to grow, an attempt to culture the bacteria in media containing these molecules has not successful. There are significant losses in the genome of M.

All the central pathways are present; M. There are pseudogenes present in M. Figure 1 shows carbon metabolism in M. Pathways in black are present in both M. Bolded carbon sources are possible for use by M. The pathway with the red arrows is the Krebs cycle. Not being able to use these sources for energy means that M. Most microbes are able to convert other sources such as galactose into glucose, but M.

Figure 2 shows respiration pathways for M. As in the previous figure, pathways in black are present in both M. NADH, one of the more common electron donors involved in metabolism in many species, is not used for electron transport in M.

This causes aerobic respiration to be much less efficient. There are no anaerobic respiration pathways in M. This makes the bacteria even harder to culture due to the difficulty of composing a media with the correct levels of oxygen and the other necessary vitamins and minerals to permit growth.

Mycobacterium leprae primarily infects the lower temperature extremities, such as the epithelial cells and nonmyelin producing Schwann cells around peripheral nerves in the hands and feet, and occasionally the upper respiratory tract, testes, and cornea, causing the disease leprosy. The symptoms of leprosy include anesthetic skin lesions and enlarged peripheral nerves. Infected areas witness less sensation to pain and temperature.

Infection usually follows breathing in through the nose microscopic droplets excreted from an infected individual containing M. There are also cases of infection when a human comes into contact with soil containing M. Skin contact with an infected individual has not proven to pass on the infection Ooi, The number of cases of individuals infected with leprosy have decreased overtime with the help of antibiotics, but there are still hundreds of thousands of cases of leprosy across the world.

It has been shown that M. Screening of new species has been performed to find potential wildlife reservoirs. Finding M. The above mentioned studies by Schilling et al. Job and colleagues looked for leprosy infections in small wild animals in Louisiana, in view of the discovered high prevalence in wild armadillos. In the armadillo study by Pedrini et al. Maruyama et al. Leprosy-like disease, attributed to mycobacteria, has been reported in a variety of animals. Phylogenetic analysis compares the genetic sequence, or a fragment thereof, and determines the similarity between two strains.

It can be visualized in a family tree, where the arms indicate the temporal distance to a previous common ancestor. Direct genetic comparison of genes can reveal overlap in sequences. This can explain overlap in characteristics of pathogens. In , a cutaneous mycobacteriosis called skin-tuberculosis was reported in Indonesian water buffaloes.

They introduced the name Lepra Bovina, as the disease had been observed in bovine species other than the water buffalo. Similar to leprosy, the microorganism could not be cultured or grown in laboratory animals.

Since a last report in , no more cases have been published. Clinical symptoms and histopathological findings indicating neural involvement were not observed. Mycobacterium lepraemurium causes leprosy-like symptoms in rats. The given name is based on the symptoms, and rather misleading, as it suggests close relation to M.

The environment is defined as any location outside the host, where M. Indications for the presence of viable M. More recent experiments are described in this section. Lavania et al. DNA is very stable and can be preserved and detected long after deposition. Later studies incorporated the detection of M. RNA is a copy of a selection of the DNA sequence needed for protein production, and has a very short half-life, often only a few hours.

Detection of M. Six samples of the non-patient area were positive by PCR. Turankar et al. SNP type 1 was detected, but subtypes varied among soil samples and patients, even when patients were related. Mohanty et al. Holanda et al. In Suriname, samples were taken from areas inhabited by the nine-banded armadillo: the villages Pikin Slee and Gujaba, and the former leprosy colonies Batavia and Groot Chatillon.

Filice et al. Physical contact was considered direct contact and living in an armadillo habitat was considered indirect contact. Schmitt et al. Truman et al.

SNP subtype 3I, generally associated with European-American populations was present in all armadillos and 26 of 29 American patients without travel history. Further analysis of subtypes using variable number tandem repeat VNTR profiles showed that one specific M. They concluded that human leprosy in Louisiana and Texas may result from contact with infected armadillos. Sharma et al. Human M.

Lymph node tissue for PCR analysis was obtained from 95 of the infected armadillos. SNP subtype 3Iv15 has not been reported outside the state of Florida.

The leprosy patients with this genotype all lived in Florida. These data show that the M. Armadillos must have acquired M.

Da Silva et al. Stratification was performed based on hunting or eating armadillos, and analyzed further based on frequency. Of individuals, over the previous year, 27 The number of leprosy patients among armadillo hunters 4 of 27, Anti-PGL I titers were different when stratifying for exposure frequency. Eating armadillo meat more than 12 times per year was associated with an insignificant increased risk of PGL I positive antibody titers OR 1. Stefani et al. Volunteers were examined for clinical signs of leprosy by a dermatologist.

Armadillo skin, spleen, liver, lymph, adrenal glands, ovary and fallopian tubes and human skin lesions suspect of leprosy were biopsied and examined histopathologically. All tissues from armadillos were tested with qPCR for the M. Six new leprosy patients were identified among the local volunteers. None of the armadillo samples showed M. Attempts at discovering vectors for M. In older studies, leprosy bacilli viability could not be shown by culture or the use of animal models.

These studies are not discussed in depth, because of their limited impact. Three studies contained only a description of the theoretical role of arthropods in the transmission of leprosy. At most, insects would take up the bacteria or transmit a small number of bacilli to a subsequent feeding target, but this would not be considered a valid transmission route. Intracellular microorganisms have been associated with free living amoebae FLA without a known benefit for either.

Such a relationship was studied for M. Phagocytosis of fluorescent M. Inside the amoebae M. S was shown by Paling et al. As amoebae are present worldwide in the environment e. Exposure of mammals to infected amoebae could be a risk factor for transmission. In this form of transmission, the amoebae would function as a vector. Acanthamoeba DNA was associated with viable M. Water samples showed the same association. The association between viable M.

Neumann et al. The mosquitoes, however, did not meet the essential criterion for a vector: the ability to maintain an infectious load of the pathogen until the next feed. But M. Inoculation of MFP with feces of kissing bugs proved that M. This is a well-known transmission pathway for Trypanosoma cruzi , causing the zoonotic, vector transmitted Chagas disease. Kissing bugs transmit disease, not by biting, but by defecating near the bite wound. Rubbing or scratching infects the wound.

Da Silva Ferreira et al. In addition, M. Infected larvae were attached to rabbit skin for a five day maturation feeding period. Afterwards, up to 10 3 viable M. The study showed an ecological cycle of M. The research group also performed the first successful cell culture of M. This systematic review assessed publications of possible non-human environmental reservoirs and transmission pathways of M.

The results show a wildlife reservoir of M. The diagnosis of leprosy in captive non-human primates is limited to case-reports, and it is unknown to what degree species are infected. Screening for the presence of these mycobacteriae in other species has been negative, except for the finding in of genetic material of M. Possible routes of transmission are schematically visualized in Fig 2.

It is justified to ask whether or not we can speak of an environmental reservoir. RNA indicating the presence of viable M. In addition, it was found that amoebae are capable of taking up M. Inside amoebae, M. This mechanism might contribute to environmental survival in the absence of a mammalian host.

Moreover, M. This gives amoebae a possible role as a vector in transmission. The only studies on vegetation reservoirs were on sphagnum species by Kazda Table 4. Humans and armadillos in the Southern United States share a specific M. It is unclear whether transmission risk by rate of exposure to infected mammals is confounded by rate of exposure to an infected environment.

This could be caused by shedding of leprosy bacteria by infected mammals. At this moment, there is no evidence for a role for vectors in transmission. However, recent laboratory studies have shown a potential role for insects. Kissing bugs can defecate after biting, and defecation near the bitten area transmits viable T. In the same study, it was found that M. It also has been shown that M. Larvae from hatched eggs in turn are able to transmit viable M. Animals can be affected by leprosy-like diseases, caused by pathogens phylogenetically closely related to M.

Insights from the transmission and reservoirs of members of the M. Currently, knowledge on the exact transmission mechanisms of M. Using insights on related pathogens is a potentially efficient way to progress. The studies included in this review differ in methods to determine the causative microorganism of leprosy.

Techniques have developed over time from identifying unspecified non-cultivable acid-fast bacteria to specific DNA sequencing. The ability to detect M. The variety of and changes in analysis methods for detection of M.

This is also relevant for studies on M. Studies on zoonosis and prevalence should be performed with sample sizes determined by the population sizes. Results of these studies have to be reported with confidence intervals, as this would substantiate the extrapolation value of the studies. Many studies in this review lack this method of sample size determination. Geographic origins of the animals are described clearly in most armadillo prevalence studies.

It is seen that prevalence fluctuates strongly between neighboring geographic regions. This limits the value of spatially and temporally randomly acquired frozen samples in screening studies, which often do not represent a wildlife sub population. Seldom are internal control standards like those normally used in clinical laboratories incorporated.

This lack of rigor contributes to the anecdotal assessment sometimes given to molecular studies reporting M.

Standardization in environmental studies should be increased by first developing appropriate definitions and sample criteria. This systematic review underscores that human-to-human transmission is not the only way leprosy can be acquired. For a more realistic view, check out this Binary Fission video.

In some cases bacteria use sexual reproduction, which is known as conjugation. In conjugation, two parent cells join together and exchange genetic information.

After the information is exchanged, the cells go through binary fission and create two new cells. For a more realistic view of conjugation, check out this video. Mycobacterium leprae will, like most bacteria, go through asexual binary fission reproduction as long as the conditions are favorable. If necessary, sexual reproduction will be used in unfavorable conditions. Designed by Free Flash Templates. The remarkable quantities of M.

Subsequent surveys confirmed that wild armadillos are a large reservoir for M. Leprosy was not present in the New World during pre-Colombian times, and it is reasonable to assume that armadillos must have acquired the infection from humans sometime in the last few centuries. They are now recognised as the only non-human reservoir of M.

Recent reports indicate that zoonotic transmission of M. The role that armadillos may play in perpetuating leprosy in the Americas is now being investigated. However, evidence is accumulating that an occult reservoir of pre-clinical asymptomatic cases, and perhaps armadillos or other environmental hosts, may play a more important role in the ecology of the disease, and leprosy probably cannot be eliminated through drug therapy alone.

Control of leprosy by vaccination or immunotherapy as an adjunct to drug therapy may have significant advantages over control by drug treatment alone. A consortium of philanthropic foundations have promoted research on new diagnostic tests and a prototype vaccine since Scientists from all over the world are engaged in these efforts and their products are now beginning to move into trial.

If technology triumphs, we may finally put an end to the suffering caused by one of the oldest known mycobacterial diseases. Masaki, T. Reprogramming adult Schwann cells to stem cell-like cells by leprosy bacilli promotes dissemination of infection.

C ell , 51— Monot, M. Comparative genomic and phylogeographic analysis of Mycobacterium leprae. N at Genet 41, — Rodrigues, L.

Leprosy now: epidemiology, progress, challenges, and research gaps.