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Infection and immunity2005; 73(8); 5106-5114; doi: 10.1128/IAI.73.8.5106-5114.2005

Establishment of cloned Anaplasma phagocytophilum and analysis of p44 gene conversion within an infected horse and infected SCID mice.

Abstract: Diverse p44 alleles at the p44 expression locus (p44Es) encoding surface-exposed major membrane proteins, P44s, of Anaplasma phagocytophilum were hypothesized to be garnered by recombination to enact antigenic variation. However, this hypothesis has not been proven so far, due to inability to clone this obligate intragranulocytic rickettsia. To define the p44E recombination, we developed a novel method to clone A. phagocytophilum. This isogenic cloned population containing a defined p44E was used to infect a naive horse and severe combined immunodeficiency (SCID) mice. During a 58-day infection period in the blood of the horse, p44E conversion was evident in a total of 11 new p44Es, 48% (115/242) of the sequenced p44E population. During a 50-day infection period in the blood of SCID mice, p44E conversion was manifested in a total of 13 new p44Es, 42% (192/460) of the p44E population. Thus, similar levels of p44E convertants were detected in either the presence or absence of an acquired immune system, suggesting that T- and B-cell immune pressure was not essential for recombination and/or selection of the p44E variants. Analysis of sequentially changed p44Es revealed that the entire central hypervariable region of donor p44 pseudogenes or of donor full-length p44s replaced the same region of the resident p44E as a cassette. Putative recombination points were detected within p44 conserved regions flanking the central hypervariable region by the TOPALi analysis. Our results unambiguously demonstrated p44E recombination. The cloning method developed would facilitate precise analysis of the recombination process and the extent of diversity which the recombination creates in the antigenic repertoire.
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Publication Date: 2005-07-26 PubMed ID: 16041027PubMed Central: PMC1201200DOI: 10.1128/IAI.73.8.5106-5114.2005Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This study presents a new method for cloning Anaplasma phagocytophilum, a type of intracellular bacteria, and uses it to investigate the process of gene conversion in a particular gene (p44) during infection in a horse and immunodeficient mice. The findings indicate that an immune response is not necessary for this gene conversion process to occur.

Research Methods and Experimentation

  • The researchers developed a novel method for cloning Anaplasma phagocytophilum. This successfully allowed them to establish an isogenic cloned population with a defined p44 gene (p44E).
  • This cloned population was then used to infect both a naive horse and Severe Combined Immunodeficiency (SCID) mice. The latter do not have a functioning immune system.
  • The infection process was observed over a period of 58 days in the horse and 50 days in the SCID mice to track the conversion of the p44E gene.

Findings

  • During the infection periods, conversion of the p44E gene, or antigenic variation, was observed in both the horse and the mice.
  • In the horse, p44E conversion was evident in a total of 11 new p44Es, which made up about 48% of the sequenced p44E population.
  • In the SCID mice, p44E conversion was identified in a total of 13 new p44Es, accounting for 42% of the p44E population.
  • These similar levels of p44E conversion were observed both in the presence (in the horse) and absence (in the SCID mice) of an immune system, suggesting that an immune response is not crucial for recombination and/or selection of the p44E variants.
  • The analysis revealed that the entire central hypervariable region of donor p44 genes or pseudogenes replaced the same region of the resident p44E in a cassette-like manner. Putative recombination points were discovered within p44 conserved regions flanking the central hypervariable region.
  • The findings conclusively demonstrate that p44E recombination occurs.

Significance

  • This study’s results provide valuable insights into the process of p44E recombination in Anaplasma phagocytophilum.
  • The novel cloning method developed here will facilitate more precise analysis of the recombination process and the diversity it creates in the antigenic repertoire of this type of bacteria.

Cite This Article

APA
Lin Q, Rikihisa Y. (2005). Establishment of cloned Anaplasma phagocytophilum and analysis of p44 gene conversion within an infected horse and infected SCID mice. Infect Immun, 73(8), 5106-5114. https://doi.org/10.1128/IAI.73.8.5106-5114.2005

Publication

Infection and immunity
ISSN: 0019-9567
NlmUniqueID: 0246127
Country: United States
Language: English
Volume: 73
Issue: 8
Pages: 5106-5114

Researcher Affiliations

Lin, Quan
  • Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, 1925 Coffey Road, Columbus, OH 43210-1093, USA.
Rikihisa, Yasuko

    MeSH Terms

    • Anaplasma phagocytophilum / genetics
    • Anaplasma phagocytophilum / metabolism
    • Animals
    • Bacterial Outer Membrane Proteins / genetics
    • Bacterial Outer Membrane Proteins / metabolism
    • Base Sequence
    • Cell Culture Techniques
    • Ehrlichiosis / metabolism
    • Ehrlichiosis / veterinary
    • Gene Conversion
    • Horses / microbiology
    • Mice
    • Mice, SCID
    • Molecular Sequence Data

    Grant Funding

    • R01 AI047407 / NIAID NIH HHS
    • R01 AI047885 / NIAID NIH HHS
    • AI47407 / NIAID NIH HHS
    • R01 AI47885 / NIAID NIH HHS

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    Citations

    This article has been cited 22 times.
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