Genetic Variability of Archived Cytauxzoon Felis Histologic Specimens from Domestic Cats in Georgia, 1995–2007

Abstract

Abstract. Cytauxzoon felis infection in domestic cats has historically been nearly 100% fatal. However, increasing reports of domestic cats that survive cytauxzoonosis and reports of asymptomatic cats with C. felis infections suggest the existence of different parasite strains that vary in pathogenicity. The objective of the current study was to obtain epidemiologic information about cytauxzoonosis through genotypic characterization of archived histologic specimens from domestic cats with C. felis infections that were diagnosed in Georgia between 1995 and 2007. Such retrospective data on genetic variability will provide an historic context for current studies of C. felis genotype frequencies. Cytauxzoon felis DNA was obtained from formalin-fixed, paraffin-embedded tissues from infected cats diagnosed with cytauxzoonosis at necropsy. Genetic characterization of C. felis was performed using sequence analysis of the polymerase chain reactionamplified ribosomal internal transcribed spacer regions 1 and 2 (ITS1, ITS2). Eleven different combined ITS1 and ITS2 sequences were identified, the majority of which were identical to those previously reported in fatally infected cats from Georgia. The findings of the current study document the existence of genetically distinct C. felis populations in historical samples and, together with data from contemporary samples, demonstrate a diverse population structure for C. felis.

Identification ofCytauxzoon felisinfection in domestic cats from southern Illinois

“…Both ITS-1 segments were identical to each other and exhibited 100% identity with EU450802, the most commonly reported ITS-1 sequence. 13,14,23 Amplification of ITS-2 yielded a 205 bp segment for sample A and a 220 bp segment for sample B. Again, the samples from Illinois were identical to each other, but the chromatograms indicated incorporation of two nucleotides (cytosine and thymine) at the position equivalent to nucleotide 76 in sample EU450804.…”

“…19 Sequence analysis of C felis DNA isolated from histologic lesions in two domestic cats from southern Illinois show either mixed infection or possible heterozygosity (cytosine and thymine) in the ITS-2 at the position equivalent to nucleotide 76 (thymine) in the most commonly isolated C felis ITS-2 sequence. 13,14 The incorporation of two nucleotides at one position in ITS-2 may indicate a single haploid organism with heterozygosity of the ITS-2 region or multiple organisms with different sequences (as many schizonts were likely sampled within each tissue section). 23…”

“…13,14,16,[21][22][23] Cytauxzoon felis ITS-1 was amplified using two primer pairs previously described: ITS-15C (5'-CGATCGAGT GATCCGGTGAATTA-3')/ITS-13B (5'-GCTGCGTCCTTC ATCGTTGTG-3') and nested forward (5'-ATAGAGTAAAC GCTTCCTTCGGC-3')/reverse (5'-CDCAGAAGTCTGC AAG TCACAATG-3') primers. 13,14 The ITS-2 segment could not be amplified with the primers described by Brown et al, 20 so new ITS-2 forward (5'-AGGTGATTTACAAT CCCTCTATATCTAC-3') and reverse (5'-TCGATGTATTG AGGAATACTGTGAT-3') primers were designed based upon the most commonly isolated C felis ITS-2 sequence. 13,14 PCR was performed with an annealing temperature of 53°C to amplify genetic segments of both ITS-1 and ITS-2.…”

“…3 Since that report, the disease has been documented in domestic cats from Arkansas, Florida, Georgia, Illinois, Kansas, Kentucky, Louisiana, Missouri, North Carolina, Oklahoma, South Carolina, Tennessee, Texas and Virginia. 2,[4][5][6][7][8][9][10][11][12][13][14][15] Cytauxzoonosis has also been reported in domestic cats from Alabama, Mississippi, Ohio and West Virginia. 1 Additionally, C felis infection has been documented in bobcats from North Dakota and Pennsylvania, 16,17 though it has not been reported in domestic cats from these two states.…”

Pharmacogenomics of Cytauxzoon felis Cytochrome b : Implications for Atovaquone and Azithromycin Therapy in Domestic Cats with Cytauxzoonosis

“…We found no association between the most common ITS genotype (ITSc; GenBank accession no. EU450802/EU450804) and survival or ITS genotype and cytochrome b genotype (see Tables S4 to S6 in the supplemental material) (16,17).…”