Involvement of mitochondrial genes of Babesia gibsoni in resistance to diminazene aceturate

Description and molecular characterisation of Babesia ailuropodae n. sp., a new piroplasmid species infecting giant pandas

BACKGROUND

Babesia spp. are protozoan parasites that infect the red blood cells of domesticated animals, wildlife and humans. A few cases of giant pandas (a flagship species in terms of wildlife conservation) infected with a putative novel Babesia sp. have been reported. However, comprehensive research on the morphological and molecular taxonomic classification of this novel Babesia sp. is still lacking. This study was designed to close this gap and formally describe this new Babesia sp. infecting giant pandas.

METHODS

Detailed morphological, molecular and phylogenetic analyses were conducted to characterise this Babesia sp. and to assess its systematic relationships with other Babesia spp. Blood samples from giant pandas infected with Babesia were subjected to microscopic examination. The 18S ribosomal RNA (18S rRNA), cytochrome b (cytb) and mitochondrial genome (mitogenome) of the new Babesia sp. were amplified, sequenced and assembled using DNA purified from blood samples taken from infected giant pandas. Based on the newly generated 18S rRNA, cytb and mitogenome sequences, phylogenetic trees were constructed.

RESULTS

Morphologically, the Babesia sp. from giant pandas exhibited various forms, including round to oval ring-shaped morphologies, resembling those found in other small canine Babesia spp. and displaying typical tetrads. Phylogenetic analyses with the 18S rRNA, cytb and mitogenome sequences revealed that the new Babesia sp. forms a monophyletic group, with a close phylogenetic relationship with the Babesia spp. that infect bears (Ursidae), raccoons (Procyonidae) and canids (Canidae). Notably, the mitogenome structure consisted of six ribosomal large subunit-coding genes (LSU1-6) and three protein-coding genes (cytb, cox3 and cox1) arranged linearly.

CONCLUSIONS

Based on coupled morphological and genetic analyses, we describe a novel species of the genus Babesia, namely, Babesia ailuropodae n. sp., which infects giant pandas.

Investigation of Babesia spp. and Theileria spp. in ticks from Western China and identification of a novel genotype of Babesia caballi

Babesia spp. and Theileria spp. are tick-borne protozoan parasites with veterinary importance. In China, epidemiological and genetic investigations on many Babesia and Theileria species were still absent in many areas and many tick species. From Aug 2021 to May 2023, 645 ticks were collected from the body surface of domestic animals (camels, goats, sheep, and cattle) using tweezers in seven counties in three provinces including Xinjiang (Qitai, Mulei, Hutubi, and Shihezi counties), Chongqing (Youyang and Yunyang counties), and Qinghai (Huangzhong county). Three tick species were morphologically and molecularly identified (334 Hyalomma asiaticum from Xinjiang, 245 Rhipicephalus microplus from Chongqing, and 66 Haemaphysalis qinghaiensis from Qinghai). A total of three Babesia species and two Theileria species were detected targeting the 18S gene. The COI and cytb sequences were also recovered from Babesia strains for further identification. In R. microplus from Chongqing, Babesia bigemina, the agent of bovine babesiosis, was detected. Notably, in H. asiaticum ticks from Xinjiang, a putative novel genotype of Babesia caballi was identified (0.90%, 3/334), whose COI and cytb genes have as low as 85.82% and 90.64-90.91% nucleotide identities to currently available sequences. It is noteworthy whether the sequence differences of its cytb contribute to the drug resistance of this variant due to the involvement of cytb in the drug resistance of Babesia. In addition, Theileria orientalis and Theileria annulata were detected in R. microplus from Chongqing (12.20%, 31/245) and H. asiaticum from Xinjiang (1.50%, 5/334), respectively. These results suggest that these protozoan parasites may be circulating in domestic animals in these areas. The pathogenicity of the novel genotype of B. caballi also warrants further investigation.

Antiparasitic Evaluation of Aquiluscidin, a Cathelicidin Obtained from Crotalus aquilus, and the Vcn-23 Derivative Peptide against Babesia bovis, B. bigemina and B. ovata

Babesiosis is a growing concern due to the increased prevalence of this infectious disease caused by Babesia protozoan parasites, affecting various animals and humans. With rising worries over medication side effects and emerging drug resistance, there is a notable shift towards researching babesiacidal agents. Antimicrobial peptides, specifically cathelicidins known for their broad-spectrum activity and immunomodulatory functions, have emerged as potential candidates. Aquiluscidin, a cathelicidin from Crotalus aquilus, and its derivative Vcn-23, have been of interest due to their previously observed antibacterial effects and non-hemolytic activity. This work aimed to characterize the effect of these peptides against three Babesia species. Results showed Aquiluscidin's significant antimicrobial effects on Babesia species, reducing the B. bigemina growth rate and exhibiting IC50 values of 14.48 and 20.70 μM against B. ovata and B. bovis, respectively. However, its efficacy was impacted by serum presence in culture, and it showed no inhibition against a B. bovis strain grown in serum-supplemented medium. Conversely, Vcn-23 did not demonstrate babesiacidal activity. In conclusion, Aquiluscidin shows antibabesia activity in vitro and its efficacy is affected by the presence of serum in the culture medium. Nevertheless, this peptide represents a candidate for further investigation of its antiparasitic properties and provides insights into potential alternatives for the treatment of babesiosis.

Multiple piroplasm parasites (Apicomplexa: Piroplasmida) in northeastern populations of the invasive Asian longhorned tick, Haemaphysalis longicornis Neumann (Ixodida: Ixodidae), in the United States

Piroplasms, which include the agents of cattle fever and human and dog babesiosis, are a diverse group of blood parasites of significant veterinary and medical importance. The invasive Asian longhorned tick, Haemaphysalis longicornis, is a known vector of piroplasms in its native range in East Asia and invasive range in Australasia. In the USA, H. longicornis has been associated with Theileria orientalis Ikeda outbreaks that caused cattle mortality. To survey invasive populations of H. longicornis for a broad range of piroplasms, 667 questing H. longicornis collected in 2021 from 3 sites in New Jersey, USA, were tested with generalist piroplasm primers targeting the 18S small subunit rRNA (395–515 bp, depending on species) and the cytochrome b oxidase loci (1009 bp). Sequences matching Theileria cervi type F (1 adult, 5 nymphs), an unidentified Theileria species (in 1 nymph), an undescribed Babesia sensu stricto (‘true’ Babesia, 2 adults, 2 nymphs), a Babesia sp. Coco (also a ‘true Babesia’, 1 adult, 1 nymph), as well as Babesia microti S837 (1 adult, 4 nymphs) were recovered. Babesia microti S837 is closely related to the human pathogen B. microti US-type. Additionally, a 132 bp sequence matching the cytochrome b locus of deer, Odocoileus virginanus, was obtained from 2 partially engorged H. longicornis. The diverse assemblage of piroplasms now associated with H. longicornis in the USA spans 3 clades in the piroplasm phylogeny and raises concerns of transmission amplification of veterinary pathogens as well as spillover of pathogens from wildlife to humans.

Cytochrome c oxydase I phylogenetic analysis of Haemogregarina parasites (Apicomplexa, Coccidia, Eucoccidiorida, Haemogregarinidae) confirms the presence of three distinct species within the freshwater turtles of Tunisia

Species of Haemogregarina are apicomplexan blood parasites that use vertebrates as intermediate hosts. Due to limited interspecific morphological characters within the genus during the last decade, 18S rRNA gene sequences were widely used for species identification. As coinfection patterns were recently reported from nuclear molecular data for two sympatric freshwater turtles Mauremys leprosa and Emys orbicularis from Tunisia, our objectives were to design COI specific primers to confirm the presence of three distinct species in both host species. Blood samples were collected from 22 turtles, from which DNAs were extracted and used as templates for amplification. Following different rounds of PCR and nested PCR, we designed specific Haemogregarina COI primers that allowed the sequencing of nine distinct haplotypes. Phylogenetic Bayesian analysis revealed the occurrence of three well-differentiated sublineages that clustered together into a single clade. Based on pairwise genetic distances (p-distance), we confirmed the occurrence of three distinct but phylogenetically closely related species coinfecting M. leprosa and E. orbicularis in the same aquatic environments. Our results demonstrate that the use of fast evolving genes within Haemogregarina will help to investigate the parasite diversity within both intermediate vertebrate and definitive invertebrate hosts, and to assess the evolution, historical biogeography and specificity of haemogregarines.

Babesia gibsoni emerging with high prevalence and co-infections in “fighting dogs” in Hungary

Babesia gibsoni is considered as an emerging protozoan parasite of dogs in North America and Europe. However, no data have been published on its prevalence, molecular-phylogenetic characteristics and associated co-infections in dogs used for illegal fighting (i.e. predisposed to acquiring this piroplasm via biting) in Europe. In this study, blood samples from 79 American Staffordshire Terrier dogs, confiscated for illegal dog fights, were molecularly analyzed for tick-borne pathogens. Babesiagibsoni was detected in 32 dogs, i.e. with a prevalence of 40.5%. In addition, Babesia vulpes was found in 8 samples (prevalence of 10.1%), for the first time in dogs in Hungary. Canine hemoplasmas were also identified in 49 samples (62%): only Mycoplasma haemocanis in 32 (40.5%) dogs, only “Candidatus Mycoplasma haematoparvum” in 9 (11.4%) dogs, and both hemoplasmas in 8 (10.1%) dogs. Thus, hemoplasma infections also showed a particularly high prevalence in this dog population. Based on a partial fragment of the 18S rRNA gene, B. gibsoni from Hungary exhibited complete sequence identity with conspecific strains reported from Europe and Asia. The cytochrome c oxidase subunit 1 (cox1) gene sequence of this isolate showed the closest identity with B. gibsoni reported from Japan but had a nonsynonymous mutation (M33I). Furthermore, the 11 B. gibsoni-positive samples analyzed for sequence variants of the cytochrome b (cytb) gene showed the presence of a common mutation (P310S). Most importantly, B. gibsoni had two further nonsynonymous mutations, M121I and F258L, in a dog with severe and relapsing anemia following atovaquone treatment. Phylogenetically, both cytb sequence variants clustered together, with a clear geographical pattern showing the closest relationship of both haplotypes identified in Hungary with those from China and Japan. To the best of our knowledge, this is the first cox1 and cytb characterization of B. gibsoni in Europe, as well as the first report on the emergence of this piroplasm and hemoplasmas with high prevalence among “fighting dogs” north of the Mediterranean Basin.

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High prevalence of Babesia gibsoni and canine hemoplasmas in “fighting dogs”.

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Molecular evidence for infection with Babesia vulpes in dogs in Hungary.

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Closest identity with sequences from Asia in two of the three genetic markers tested.

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Two unique nonsynonymous mutations of B. gibsoni in the case of a dog.

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First report of atovaquone resistance for B. gibsoni in Europe.

Reduced expression levels of heat shock protein 90 in a diminazene aceturate-resistant Babesia gibsoni isolate

Heat shock protein 90 (HSP90) is a molecular chaperon and an essential component for stage differentiation and intracellular growth inside the host cells of many protozoans. HSP90 of Babesia gibsoni (BgHSP90) was suggested to function in the development of diminazene aceturate (DA)-resistance. Therefore, we examined the expression level of BgHSP90 in a DA-resistant B. gibsoni isolate. Transcription of the BgHSP90 gene in the DA-resistant isolate and wild-type B. gibsoni was assessed by quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR). As a result, the copy number and relative amount of BgHSP90 transcripts in the DA-resistant isolate were significantly lower than those in the wild-type. Moreover, a rabbit anti-recombinant BgHSP90 antibody was developed, and the protein synthesis of BgHSP90 in the DA-resistant isolate was compared with that in the wild-type by Western blot analysis and indirect fluorescence assay. There was significantly less BgHSP90 protein than in the wild-type. Additionally, the relative intensity of BgHSP70 in DA-resistant isolate was also lower than that in the wild-type. This suggested that the expression of BgHSP90 and BgHSP70 in the DA-resistant B. gibsoni isolate was suppressed and that the reduced amount of BgHSP90 and BgHSP70 might cause the weak proliferation of the DA-resistant isolate. Further studies are necessary to elucidate the function of BgHSP90.

In vitro and in vivo growth inhibitory activities of cryptolepine hydrate against several Babesia species and Theileria equi

Piroplasmosis treatment has been based on the use of imidocarb dipropionate or diminazene aceturate (DA), however, their toxic effects. Therefore, the discovery of new drug molecules and targets is urgently needed. Cryptolepine (CRY) is a pharmacologically active plant alkaloid; it has significant potential as an antiprotozoal and antibacterial under different in vitro and in vivo conditions. The fluorescence assay was used for evaluating the inhibitory effect of CRY on four Babesia species and Theileria equi in vitro, and on the multiplication of B. microti in mice. The toxicity assay was evaluated on Madin–Darby bovine kidney (MDBK), mouse embryonic fibroblast (NIH/3T3), and human foreskin fibroblast (HFF) cell lines. The half-maximal inhibitory concentration (IC₅₀) values of CRY on Babesia bovis, B. bigemina, B. divergens, B. caballi, and T. equi were 1740 ± 0.377, 1400 ± 0.6, 790 ± 0.32, 600 ± 0.53, and 730 ± 0.025 nM, respectively. The toxicity assay on MDBK, NIH/3T3, and HFF cell lines showed that CRY affected the viability of cells with a half-maximum effective concentration (EC₅₀) of 86.67 ± 4.43, 95.29 ± 2.7, and higher than 100 μM, respectively. In mice experiments, CRY at a concentration of 5 mg/kg effectively inhibited the growth of B. microti, while CRY–atovaquone (AQ) and CRY–DA combinations showed higher chemotherapeutic effects than CRY alone. Our results showed that CRY has the potential to be an alternative remedy for treating piroplasmosis.

The development and evaluation of new treatment strategies against Babesia and Theileria parasites have become increasingly urgent due to the emergence of parasite resistance and unwanted toxicity side effects by current chemotherapies. On the other hand, vaccination is a cheaper, reliable and sustainable option. Unfortunately, it has not worked well for the protozoan diseases because they possess ingenious mechanisms to evade the host immune system, rendering treatment the most suitable approach for their control. Sadly, only diminazene aceturate (DA) and imidocarb dipropionate have passed clinical trials for the treatment of piroplasmosis. However, these drugs cause many adverse effects and not approved yet for human medicine. Cryptolepine (CRY) is a pharmacologically active indoloquinoline alkaloid isolated from the roots of the shrub Cryptolepis sanguinolenta. CRY is reported to possess various pharmacological activities, including antifungal, anti-mycobacterial, and potent antiplasmodial activities. In the present study we evaluated the effects of CRY against the growth of Babesia bovis, B. bigemina, B. divergens, B. caballi and Theileria equi in vitro and its chemotherapeutic potential on Babesia microti in mice. Furthermore, we investigated the effect of combination between CRY with the current babesiocidal drugs such as DA, atovaquone (AQ) and clofazimine (CF) in vitro and in vivo.

Therapeutic Effects of Atranorin towards the Proliferation of Babesia and Theileria Parasites

Atranorin (ATR), is a compound with multidirectional biological activity under different in vitro and in vivo conditions and it is effective as an antibacterial, antiviral, antiprotozoal and anti-inflammatory agent. In the current study, the in vitro as well as in vivo chemotherapeutic effect of ATR as well as its combined efficacy with the existing antibabesial drugs (diminazene aceturate (DA), atovaquone (AV) and clofazimine (CF)) were investigated on six species of piroplasm parasites. ATR suppressed B. bovis, B. bigemina, B. divergens, B. caballi and T. equi multiplication in vitro with IC₅₀ values of 98.4 ± 4.2, 64.5 ± 3.9, 45.2 ± 5.9, 46.6 ± 2.5, and 71.3 ± 2.7 µM, respectively. The CCK test was used to examine ATR's cytotoxicity and adverse effects on different animal and human cell lines, the main hosts of piroplasm parasites and it showed that ATR affected human foreskin fibroblasts (HFF), mouse embryonic fibroblast (NIH/3T3) and Madin-Darby Bovine Kidney (MDBK) cell viability in a dose-related effect with a moderate selective index. The combined efficacy of ATR with DA, CF, and AV exhibited a synergistic and additive efficacy toward all tested species. In the in vivo experiment, ATR prohibited B. microti multiplication in mice by 68.17%. The ATR-DA and ATR-AV combination chemotherapies were more potent than ATR monotherapy. These results indicate the prospects of ATR as a drug candidate for piroplasmosis treatment.

Babesia gibsoni endemic to Wuhan, China: mitochondrial genome sequencing, annotation, and comparison with apicomplexan parasites

Babesia gibsoni (B. gibsoni), an intracellular apicomplexan protozoan, poses great threat to canine health. Currently, little information is available about the B. gibsoni (WH58) endemic to Wuhan, China. Here, the mitochondrial (mt) genome of B. gibsoni (WH58) was amplified by five pairs of primers and sequenced and annotated by alignment with the reported mt genome sequences of Babesia canis (B. canis, KC207822), Babesia orientalis (KF218819), Babesia bovis (AB499088), and Theileria equi (AB499091). The evolutionary relationships were analyzed with the amino acid sequences of cytochrome c oxidase I (cox1) and cytochrome b (cob) genes in apicomplexan parasite species. Additionally, the mt genomes of Babesia, Theileria, and Plasmodium spp. were compared in size, host infection, form, distribution, and direction of the protein-coding genes. The full size of the mt genome of B. gibsoni (WH58) was 5865 bp with a linear form, containing terminal-inverted repeats on both ends, six large subunit ribosomal RNA fragments, and three protein-coding genes: cox1, cob, and cytochrome c oxidase III (cox3). Babesia, Theileria, and Plasmodium spp. had a similar mt genome size of about 6000 bp. The mt genomes of parasites that cause canine babesiosis showed a slightly smaller size than the other species. Moreover, Babesia microti (R1 strain) was about 11,100 bp in size, which was twice larger than that of the other species. The mt form was linear for Babesia and Theileria spp. but circular for Plasmodium falciparum and Plasmodium knowlesi. Additionally, all the species contained the three protein-coding genes of cox1, cox3, and cob except Toxoplasma gondii (RH strain) which only contained the cox1 and cob genes. The phylogenetic analysis indicated that B. gibsoni (WH58) was more identical to B. gibsoni (AB499087), B. canis (KC207822), and Babesia rossi (KC207823) and most divergent from Babesia conradae in Babesia spp. Despite the highest similarity to B. gibsoni (AB499087) reported in Japan, B. gibsoni (WH58) showed notable differences in the sequence of nucleotides and amino acids and the property in virulence to host and in vitro cultivation. This study compared the mt genomes of the two B. gibsoni isolates and other parasites in the phylum Apicomplexa and provided new insights into their differences and evolutionary relationships.

17-DMAG inhibits the multiplication of several Babesia species and Theileria equi on in vitro cultures, and Babesia microti in mice

Heat shock protein 90 (Hsp90) is a chaperone protein that stabilizes cells during stress or non-stress responses. Previous reports have shown that Hsp90 is a potential drug target to suppress the multiplication of several protozoan parasites. In this study, 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG), an Hsp90 inhibitor, was evaluated for its inhibitory effect on five in vitro cultures of Babesia and Theileria species, including B. bovis, B. bigemina, B. divergens, B. caballi, and T. equi, and on the multiplication of a B. microti–infected mouse model. 17-DMAG showed the inhibitory effect in all of the species tested. The half maximum inhibition concentration (IC₅₀) of 17-DMAG on B. bovis, B. bigemina, B. divergens, B. caballi, and T. equi was 77.6 ± 2.9, 62.4 ± 1.9, 183.8 ± 3.2, 88.5 ± 9.6, and 307.7 ± 7.2 nM, respectively. The toxicity assay on MDBK and NIH/3T3 cell lines showed that 17-DMAG affected the viability of cells with an IC₅₀ of 15.5 ± 4 and 8.8 ± 2 μM, respectively. Since the IC₅₀s were much lower on the parasites than on the host cell lines, the selectivity index were high for all tested species. Furthermore, the two-drug combination of 17-DMAG with diminazene aceturate (DA) and atovaquone (AV) showed synergism or addition on in vitro cultures of Babesia and Theileria parasites. In the mouse model, 17-DMAG at a concentration of 30 mg/kg BW effectively inhibited the multiplication of B. microti. Moreover, if combined with DA or AV, 17-DMAG showed a comparable inhibition at the half dose. Taken together, these results indicate that 17-DMAG is a potent drug for treating piroplamosis. The data warrant further evaluation of 17-DMAG as an antibabesial drug and as an option in combination with atovaquone for the treatment of human babesiosis.

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17-DMAG inhibits the in vitro multiplication of Babesia and Theileria parasites.

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Combination of 17-DMAG with diminazene aceturate or atovaquone were also effective.

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17-DMAG also inhibits the multiplication of B. microti in mice.

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17-DMAG is a new treatment option for babesiosis in animal and human.

Chemotherapeutic efficacies of a clofazimine and diminazene aceturate combination against piroplasm parasites and their AT-rich DNA-binding activity on Babesia bovis

Recently, we reported that clofazimine (CF) has an anti-piroplasm activity, but it could not completely eliminate parasites in the host. The currently available anti-piroplasm drug, diminazene aceturate (DA), has sometimes been reported to have toxic side effects. In the present study, we evaluated the combination treatment with CF and DA against piroplasms both in vitro and in vivo. Additionally, mRNA level and DNA amounts were analyzed in CF‒ and DA‒treated Babesia bovis by a qPCR. The CF-DA combination had additive effects on Babesia bovis, B. bigemina, and B. caballi and synergistic effects on Theileria equi. The CF-DA combination chemotherapies against B. microti in mice were more potent than their monotherapies. In the CF‒ and DA‒treated B. bovis, CF dose-dependently down-regulated mRNA level and DNA amounts of extranuclear genes (AT-rich featured), whereas DA down-regulated only DNA amounts of extranuclear genes, but those of nuclear genes were slightly down- or up-regulated by CF and DA. In conclusion, the CF-DA combination has a higher efficiency against piroplasms than CF or DA monotherapies. CF and DA might have an AT-rich DNA-binding activity. All results suggest that the CF-DA combination chemotherapy will be a better choice to treat piroplasmosis instead of DA monotherapy.

The epidemiological survey for atovaquone resistant related gene of Babesia gibsoni in Japan

In 73 gDNA samples from Babesia gibsoni-infected dogs, the M121I variant population was measured by using allele-specific real-time PCR. Although the mechanism of atovaquone against B. gibsoni has not been clearly identified, it is reported that the mitochondria cytochrome b gene of the atovaquone-resistant B. gibsoni had a single-nucleotide substitution at nt363 (G to T), which resulted in the substitution of methionine with isoleucine (M121I). In this study, 3/73 samples showed over 5% M121I variant population. Although the M121I variant population is a low percentage, it runs the risk of spreading drug-resistant parasites. It is important to prevent the spread of drug-resistance, so we need to gather information about this at regular intervals.

Vaccines against bovine babesiosis: where we are now and possible roads ahead

SUMMARY Bovine babesiosis caused by the tick-transmitted haemoprotozoans Babesia bovis, Babesia bigemina and Babesia divergens commonly results in substantial cattle morbidity and mortality in vast world areas. Although existing live vaccines confer protection, they have considerable disadvantages. Therefore, particularly in countries where large numbers of cattle are at risk, important research is directed towards improved vaccination strategies. Here a comprehensive overview of currently used live vaccines and of the status quo of experimental vaccine trials is presented. In addition, pertinent research fields potentially contributing to the development of novel non-live and/or live vaccines are discussed, including parasite antigens involved in host cell invasion and in pathogen-tick interactions, as well as the protective immunity against infection. The mining of available parasite genomes is continuously enlarging the array of potential vaccine candidates and, additionally, the recent development of a transfection tool for Babesia can significantly contribute to vaccine design. However, the complication and high cost of vaccination trials hinder Babesia vaccine research, and have so far seriously limited the systematic examination of antigen candidates and prevented an in-depth testing of formulations using different immunomodulators and antigen delivery systems.

Failure of efficacy and adverse events associated with dose-intense diminazene diaceturate treatment of chronic Cytauxzoon felis infection in five cats

Cytauxzoon felis is a hemoprotozoan parasite of cats. While many infected cats die of acute illness, some enter a chronic carrier state. To date, no treatment has been documented to clear the chronic carrier state, leaving recovered cats to act as a potential indirect source of infection via a tick vector. Diminazene diaceturate is an anti-protozoal therapy that has been suggested for use in the treatment of acute cytauxzoonosis, but which failed to clear the carrier state at the dose used in acute illness. We hypothesized that a dose-intensified regimen of diminazene could reduce or eliminate parasitemia from five domestic cats naturally infected with C felis. Cats were administered 4 mg/kg of diminazene diaceturate intramuscularly for 5 consecutive days. Clearance of the organism was assessed via semi-quantitative polymerase chain reaction and light microscopy 1, 3, 6 and 10 weeks after starting treatment. Additionally, cats were monitored for adverse drug reactions by daily observation and examination. Complete blood count, biochemical profile and urinalysis were performed at 1, 3 and 10 weeks. Adverse events were common and included profuse salivation and nausea at the time of injection, monoparesis in the injected leg, proteinuria and potential hepatotoxicity. Severity of parasitemia was not reduced. Diminazene diaceturate cannot be recommended for elimination of the carrier state of C felis infection.

Pharmacogenomics of Cytauxzoon felis cytochrome b: implications for atovaquone and azithromycin therapy in domestic cats with cytauxzoonosis

Cytauxzoon felis, an emerging virulent protozoan parasite that infects domestic cats, is treated with atovaquone and azithromycin (A&A). Atovaquone targets parasite cytochrome b. We characterized the C. felis cytochrome b gene (cytb) in cats with cytauxzoonosis and found a cytb genotype that was associated with survival in A&A-treated cats.