Detection of genotype-specific Ehrlichia canis exposure in Brazilian dogs by TRP36 peptide ELISA.
We recently characterized a novel genotype of Ehrlichia canis based on the tandem repeat (TR) sequence of the TRP36 gene in Brazil. The TR amino acid sequence of the Brazilian (Br) genotype (ASVVPEAE) was divergent from the previously described US genotype (TEDSVSAPA) of E. canis. In this study, we developed an ELISA based on TRP36 TR synthetic peptides from both Br and US E. canis TRP36 genotypes to serologically detect and distinguish infections caused by these genotypes. Sera from 30 Brazilian dogs naturally infected with E. canis, sera from dogs experimentally infected E. canis (Jake and Cuiabá #1 strains) and E. chaffeensis (Arkansas strain) and 12 seronegative E. canis dogs were evaluated. Fifteen naturally infected Brazilian dogs had antibodies that reacted with the US TRP36 (n=9) or Br TRP36 (n=6) only, and 13 dogs had antibodies that reacted with both TPR36 peptides suggesting that these dogs were exposed to both genotypes. Most dogs (n=28) had antibodies that reacted with the highly conserved E. canis TRP19 peptide; however, two dogs had antibodies to E. canis TRP19, but did not have TRP36 antibodies, raising the possibility that another novel TRP36 genotype is circulating in Brazil. Our results demonstrate that synthetic peptides based on the TR region of E. canis TRP36 can be used to serologically distinguish infections or identify coinfections by different genotypes, and to determine the seroprevalence of various E. canis genotypes in Brazil.
Department of Pathology, Center of Biodefense and Emerging Infectious Diseases, Sealy Center for Vaccine Development and Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA; Laboratório de Virologia e Rickettsioses, Hospital Veterinário da Universidade Federal de Mato Grosso (HOVET-UFMT), Cuiabá, MT, Brazil. Electronic address: danmoura@ufmt.br.
Daniel M
DM
Aguiar
Department of Pathology, Center of Biodefense and Emerging Infectious Diseases, Sealy Center for Vaccine Development and Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA.
Xiaofeng
X
Zhang
Laboratório de Virologia e Rickettsioses, Hospital Veterinário da Universidade Federal de Mato Grosso (HOVET-UFMT), Cuiabá, MT, Brazil.
Isis A
IA
Braga
Laboratório de Virologia e Rickettsioses, Hospital Veterinário da Universidade Federal de Mato Grosso (HOVET-UFMT), Cuiabá, MT, Brazil.
Isis I G G
IIGG
Taques
Department of Pathology, Center of Biodefense and Emerging Infectious Diseases, Sealy Center for Vaccine Development and Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA.
Jere W
JW
McBride
D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001938:Brazil / Q000453:epidemiology; D004283:Dog Diseases / Q000453:epidemiology / Q000382:microbiology*; D004285:Dogs; D041061:Ehrlichia canis / Q000235:genetics*; D016873:Ehrlichiosis / Q000453:epidemiology / Q000662:veterinary*; D015964:Gene Expression Regulation, Bacterial; D005838:Genotype
D000907:Antibodies, Bacterial; D001426:Bacterial Proteins
Brazil; ELISA; Ehrlichia; Genotype; Immunodiagnosis; Tandem repeat protein