Identification of novel Babesia and Theileria genotypes in the endangered marsupials, the woylie (Bettongia penicillata ogilbyi) and boodie (Bettongia lesueur)

Piroplasms, which include the genera Theileria and Babesia, are blood-borne parasites transmitted mainly by tick vectors. Relatively little is known about their prevalence and clinical impact in Australian marsupials. In the present study the occurrence and molecular phylogeny of these parasites were studied in both wild and captive marsupials from Western Australia (WA) and Queensland (QLD). Blood samples were screened by microscopy and molecular methods, using PCR and DNA sequencing of the 18S ribosomal RNA gene (18S rDNA). Overall, 7.1% of the blood samples (8/113) were positive for piroplasm 18S rDNA. Theileria and Babesia rDNA was detected in 0.9% (1/113) and 6.2% (7/113) of the animals, respectively. The single Theileria positive was identified in one of three boodies (Bettongia lesueur) screened from a wildlife rehabilitation centre in WA, while all seven Babesia positives were detected in WA in wild captured woylies (Bettongia penicillata ogilbyi). Small intraerythrocytic inclusions were observed in blood films made from six of these individuals. This is the first report of a Babesia sp. in woylies, and Theileria sp. in boodies. Phylogenetic analysis indicated that the woylie-derived Babesia was genetically distinct and most closely related to Babesia occultans, the causative agent of a benign form of cattle babesiosis (genetic similarity 98.4%). The Theileria identified was most closely related to the marsupial-derived species Theileria penicillata from the woylie, Theileria brachyuri from the quokka (Setonix brachyurus), and Theileria sp. from the long-nosed potoroo (Potorous tridactylus).     

Detection and identification of Theileria infection in sika deer ( Cervus nippon ) in China

The sika deer ( Cervus nippon ) is a first-grade state-protected animal in China and designated a threatened species by the World Conservation Union. To detect hemoparasite infection of sika deer, blood samples were collected from 24 animals in the Hubei Province Deer Center. Genomic DNA was extracted, and the V4 hypervariable region encoding 18S rRNA was analyzed by reverse line blot hybridization assay. PCR products hybridized with Babesia / Theileria genus-specific probes but failed to hybridize with any of the Babesia or Theileria species-specific probes, suggesting the presence of a novel, or variant, species. Here 18S rRNA and internal transcribed spacer (ITS) genes were amplified, cloned, and sequenced from 7 isolates. Alignment and BlastN of the cloned sequences revealed high similarities to the homologous 18S rRNA genes and ITS genes of Theileria cervi (AY735122), Theileria sp. CNY1A (AB012194), and Theileria sp. ex Yamaguchi (AF529272). Phylogenetic analysis based on the 18S rRNA gene and ITS sequences showed that all cloned sequences were grouped within the Theileria clade. Phylogeny based on the 18S rRNA gene divided the organisms into 2 groups. Group 1 was closest to Theileria sp. ex Yamaguchi (AF529272), and group 2 was distinct from all other identified Theileria and Babesia species. These results suggest the existence of Theileria sp. infection in sika deer in China. To our knowledge, this is the first report of cervine Theileria sp. in China.     

Description of Babesia duncani n.sp. (Apicomplexa: Babesiidae) from humans and its differentiation from other piroplasms

The morphologic, ultrastructural and genotypic characteristics of Babesia duncani n.sp. are described based on the characterization of two isolates (WA1, CA5) obtained from infected human patients in Washington and California. The intraerythrocytic stages of the parasite are morphologically indistinguishable from Babesia microti, which is the most commonly identified cause of human babesiosis in the USA. Intraerythrocytic trophozoites of B. duncani n.sp. are round to oval, with some piriform, ring and ameboid forms. Division occurs by intraerythrocytic schizogony, which results in the formation of merozoites in tetrads (syn. Maltese cross or quadruplet forms). The ultrastructural features of trophozoites and merozoites are similar to those described for B. microti and Theileria spp. However, intralymphocytic schizont stages characteristic of Theileria spp. have not been observed in infected humans. In phylogenetic analyses based on sequence data for the complete18S ribosomal RNA gene, B. duncani n.sp. lies in a distinct clade that includes isolates from humans, dogs and wildlife in the western United States but separate from Babesia sensu stricto, Theileria spp. and B. microti. ITS2 sequence analysis of the B. duncani n.sp. isolates (WA1, CA5) show that they are phylogenetically indistinguishable from each other and from two other human B. duncani-type parasites (CA6, WA2 clone1) but distinct from other Babesia and Theileria species sequenced. This analysis provides robust molecular support that the B. duncani n.sp. isolates are monophyletic and the same species. The morphologic characteristics together with the phylogenetic analysis of two genetic loci support the assertion that B. duncani n.sp. is a distinct species from other known Babesia spp. for which morphologic and sequence information are available.     

Tick-borne diseases in ruminants of Central and Southern Italy: epidemiology and case reports

Sera and blood from cattle and sheep were examined for the presence of Babesia and Theileria spp by microscopy and serology at the Parasitology Department of the Istituto Zooprofilattico Sperimentale of Abruzzo and Molise (IZSAM). Of the 47 bovine herds (323 animals) tested, 15 were found positive for Babesia bigemina and 1 for Babesia bovis. Two outbreaks occurred, one caused by B. bigemina and one by B. bovis. The B. bigemina outbreak occurred in Abruzzo and has been followed for two years. The isolate of B. bigemina was very pathogenic leading to the death of two cows out of 57. The vector responsible of the transmission appeared to be Rhipicephalus bursa. Parasites were observed in the erythrocytes for 30 days whereas sera were positive to indirect immunofluorescence (IFA) for at least one year. The B. bovis outbreak occurred in the province of Mantova (Northern Italy) in a group of 70 beef cattle imported from France. The infection resulted in the death of 5 animals and severe illness in another 6. In contrast with what occurred for Babesia infection, no clinical cases were recorded in cattle when species of Theileria were detected by microscopy. Of the 24 bovine herds (252 animals) tested for Theileria, 21 were found positive for the T. "sergenti"/buffeli/orientalis group. Single and mixed infection of T. "sergenti" and T. buffeli/orientalis were detected in herds of cross-bred cattle from Abruzzo and Marche. The parasites were identified by using a polymerase chain reaction which amplified DNA encoding p32/34. Most of the collected ticks (90%) were adults of R. bursa whereas the others were adults of Hyalomma detritum. During the period the animals have been observed (18 months), no clinical cases have been recorded and no associations have been found between blood abnormalities and animals found infected with Theileria. Prevalences of subclinically infected carriers increased from February till December (95.4%) even if the animals were indoors and no ticks were present. The prevalence then dropped dramatically six months later (76.7%). In calves less than 1 year old, the prevalence of infection significantly (p<0.05) increased with age, however intraerythrocytic stages of Theileria were found in the blood of three newborn calves (<7 days of age). Of the 18 ovine flocks tested for Babesia spp. (150 animals examined), 1 was positive for B. ovis and 2 for B. motasi. B. motasi infection was not associated with symptoms, while an outbreak of babesiosis caused by B. ovis occurred in Abruzzo. The infection resulted in the death of 3 animals (0.75% of the flock), two rams (20% of the total number) and a ewe, and severe illness in another 5 ewes (2% of the flock). Specimens of R. bursa and R. turanicus were collected from the infected animals. Of the 18 flocks (150 animals) examined, 12 were microscopically positive for Theileria spp. No clinical cases were recorded and identification at species level was not possible on the basis of morphological criteria. The prevalence distribution of infected herds and infected animals within herds and flocks have been calculated by a Monte Carlo simulation model, running 10,000 iterations. The most likely levels of prevalence of infected herds and infected animals within herds found for the species observed were as follows: 20% for B. bigemina with a prevalence within herd of 27%, 11% for B. bovis (18% within herd), 10% for Babesia ovis (19% within herd), 10% for B. motasi (17.5% within herd), 63% for Theileria in cattle (66% within herd) and 51% for Theileria in sheep (55% within herd).     

The first detection of Babesia species DNA from Japanese black bears (Ursus thibetanus japonicus) in Japan

In this study, we tried to detect protozoan blood parasites from the liver or blood of 156 Japanese black bears (Ursus thibetanus japonicus) in Iwate Prefecture of Japan by polymerase chain reaction. Two amplicons (approximately 540 bp and 480 bp) were detected by amplification for V4 hyper-variable regions of the 18S rRNA gene. Approximately 540-bp products were obtained in 119 samples (76.3%) and were considered to be DNA of Hepatozoon ursi. Approximately 480-bp products were obtained in 22 samples (14.1%) and were considered to be DNA of Babesia species. The nucleotide sequences (1635 bp) of the 18S rRNA gene of Babesia sp. were very similar (99.3%) to those (AY190123, AY190124) of Babesia sp. detected previously from Ixodes ovatus. Phylogenetic analysis showed that Babesia sp. detected in this study closely related to Babesia sp. derived from raccoons in Japan and the U.S.A. This is the first report of Babesia species detected from Japanese black bears.     

A study on the determination of risk factors associated with babesiosis and prevalence of Babesia sp., by PCR amplification, in small ruminants from Southern Punjab (Pakistan)

Babesiosis is a parasitic infection due to the multiplication of tick borne parasite, Babesia sp., in erythrocytes of host, which includes a wide variety of vertebrates including small ruminants causing decreased livestock output and hence economic losses. The objective of the present study was to establish a PCR based method for the detection of Babesia sp. in small ruminant population in Southern Punjab and to determine the risk factors involve in the spread of babesiosis. A total of 107 blood samples were collected from 40 sheep and 67 goats in seven districts of Southern Punjab from randomly selected herds. Data on the characteristics of the animals and the herd were collected through questionnaires. 36 blood samples (34% of total) produced the DNA fragment specific for 18S rRNA gene of Babesia sp., by PCR amplification, of which 20 were sheep and 16 were goats. Samples from all seven district contained Babesia positive samples and prevalence varied between 18 to 68%. It was observed that male animals (P = 0.009) and young animals under one year of age (P = 0.01) were more prone to the parasite. It was observed that herds consist of more than 15 animals (P = 0.007), composed of mixed species of small ruminants (P = 0.022), associated with dogs (P = 0.003) and dogs having ticks on their bodies (P = 0.011) were among the major risk factors for the spread of babesiosis in small ruminants.     

First report on the occurrence of Theileria sp. OT3 in China

Theileria sp. OT3 was firstly detected and identified from clinically healthy sheep in Xinjiang Uygur Autonomous Region of China (XUAR) through comparing the complete 18S rDNA gene sequences available in GenBank database and the phylogenetic status based on the internal transcribed spacers (ITS1, ITS2) as well as the intervening 5.8S coding region of the rRNA gene by the methods of a partitioned multi-locus analysis in BEAST and Maximum likelihood analysis in PhyML. Moreover, the findings were confirmed by the species-specific PCR for Theileria sp. OT3 and the prevalence of Theileria sp. OT3 was 14.9% in the north of XUAR. This study is the first report on the occurrence of Theileria sp. OT3 in China.     

Diversity of Babesia and Theileria species in symptomatic and asymptomatic dogs in Croatia

Babesiosis, the disease caused by tick-borne hematozoan parasites of the genus Babesia, is particularly common in dogs, and is caused by several “large” species of Babesia, as well as by an increasing number of “small” species of Babesia, some of which appear to be more closely related to members of the genus Theileria. In this work, blood samples were collected from 848 randomly selected, asymptomatic dogs and from 81 symptomatic dogs, microscopically positive for Babesia, and characterised by PCR and sequence analysis of a fragment of the ssrRNA gene. A prevalence of 3.42% (29 of 848) was found in asymptomatic dogs and sequence analysis revealed the presence of Babesia canis canis in 20 dogs (69%), Babesia gibsoni in six dogs (21%), Babesia canis vogeli in two dogs (7%) and Theileria annae in one dog (3%). In the group of symptomatic dogs, which were all positive by PCR, B. canis canis was the predominant species (78 dogs, or 96%), followed by single infections with B. canis vogeli, Babesia caballi and Theileria equi. Our study has confirmed that dogs are infected with a wide range of both large and small piroplasm species and subspecies, including B. caballi and T. equi, two parasites usually found in horses. The detection of the pathogenic species B. canis canis and B. gibsoni in asymptomatic dogs indicates that the relationship between parasite species/subspecies and clinical signs of infection in dogs deserves further investigation. Finally, the identities of the tick vectors transmitting T. annae and B. caballi remain to be elucidated.     

A recently identified ovine Babesia in China: Serology and sero-epidemiology

Babesia sp. in Xinjiang, transmitted by Hyalomma, is a large Babesia that is infective for small ruminants, but it has almost no pathogenicity in healthy sheep. On the basis of the sequences of the 18S rRNA and internal transcribed spacer (ITS) genes, morphological characteristics, vector tick species and pathogenicity it was identified recently as a novel Babesia species. In the present study, an enzyme-linked immunosorbent assay (ELISA) was developed using soluble merozoite antigens of Babesia sp. in Xinjiang (BXJMA) derived from in vitro culture. When the positive threshold was chosen as 24.65% of the specific mean antibody rate, the specificity and sensitivity were both 97.3%. There was no cross-reaction between BXJMA and positive sera from sheep infected with other Chinese ovine piroplasms or Anaplasma ovis in the ELISA and western blotting. Specific antibodies against Babesia sp. in Xinjiang could be detected 2weeks post infection and a high level of antibodies persisted for more than 12weeks in experimentally infected sheep. The ELISA was tested on 3857 sera collected from small ruminants in 50 prefectures of 22 provinces to evaluate the sero-epidemiology of Babesia sp. in Xinjiang infection, and the average positive rate was 31.66%. These data provide that the developed ELISA is a powerful tool for the sero-diagnosis of Babesia sp. in Xinjiang and confirm that it is a novel species.     

Molecular phylogeny of Babesia poelea from brown boobies (Sula leucogaster) from Johnston Atoll, central Pacific

The phylogenetic relationship of avian Babesia with other piroplasms remains unclear, mainly because of a lack of objective criteria such as molecular phylogenetics. In this study, our objective was to sequence the entire 18S, ITS-1, 5.8S, and ITS-2 regions of the rRNA gene and partial beta-tubulin gene of B. poelea, first described from brown boobies (Sula leucogaster) from the central Pacific, and compare them to those of other piroplasms. Phylogenetic analyses of the entire 18S rRNA gene sequence revealed that B. poelea belonged to the clade of piroplasms previously detected in humans, domestic dogs, and wild ungulates in the western United States. The entire ITS-1, 5.8S, ITS-2, and partial beta-tubulin gene sequence shared conserved regions with previously described Babesia and Theileria species. The intron of the beta-tubulin gene was 45 bp. This is the first molecular characterization of an avian piroplasm.     

Molecular detection and identification of piroplasms (Babesia spp. and Theileria spp.) and Anaplasma phagocytophilum in questing ticks from northwest Spain

Anaplasma phagocytophilum and some piroplasm species are pathogens mainly transmitted by Ixodes ricinus. Considering that this tick species is predominant in north‐western Spain, individual specimens (652 nymphs, 202 females and 202 males) and 23 larval pools were processed to determine the prevalence of these pathogens in questing I. ricinus from that region. Additionally, Dermacentor marginatus, Dermacentor reticulatus, Ixodes frontalis and Ixodes acuminatus were individually analysed. The groESL operon as well as the 16S rRNA and msp2 genes of Anaplasma were analysed. Similarly, piroplasms were identified at the 18S rRNA gene and the ITS1 of Babesia spp. and Theileria spp. Babesia venatorum (1.5%), A. phagocytophilum (0.7%), Babesia microti (0.3%) and Theileria sp. OT3 (0.2%) were detected in I. ricinus. A single I. frontalis (8.3%) tested positive to A. phagocytophilum. Although a low percentage of I. ricinus were infected with A. phagocytophilum and piroplasms, a potentially human pathogenic variant of A. phagocytophilum was detected, and both Babesia species found were zoonotic. Since the vector of Theileria sp. OT3 remains unknown, further investigations are needed to unravel the role of I. ricinus in the transmission of this piroplasm.     

Detection of Babesia caballi in Amblyomma variegatum ticks (Acari: Ixodidae) collected from cattle in the Republic of Guinea

A reverse line blot hybridisation (RLB) assay was applied to screen Amblyomma variegatum adult ticks (n = 504) collected from N'Dama cattle in the Republic of Guinea. In a PCR, the V1 hypervariable region of the 16S ribosomal RNA (rRNA) gene was amplified with a set of primers unique for species of the genera Anaplasma and Ehrlichia, and the V4 hypervariable region of the 18S rRNA gene was amplified with primers specific for members of the genera Theileria and Babesia. Amplified PCR products from A. variegatum ticks were hybridised onto a membrane, to which oligonucleotide probes species-specific for Ehrlichia/Anaplasma and Theileria/Babesia parasites were covalently linked. No pathogens belonging to Ehrlichia/Anaplasma species were found, while 10 DNA samples resulted positive for Babesia caballi and 5 samples for Theileria velifera. This is the first report of B. caballi in A. variegatum ticks. One of the B. caballi positive samples was sequenced. This new strain (BcabGuinea) showed a 97% similarity to the Z15104 B. caballi GenBank sequence.     

First report of Rangelia vitalii infection (canine rangeliosis) in Argentina

A 12-year old mixed breed neutered bitch from Misiones, Argentina, was presented with a history of fever and epistaxis. Blood, bone marrow, and lymph node samples were collected for hematology and cytology. Mild regenerative anemia was recorded and large, round, poorly stained piroplasms (> 2.5 μm) were found within erythrocytes in blood and lymph node smears. Nested PCR-RFLP on blood and bone marrow samples was positive for piroplasm DNA. The 18S rRNA gene of piroplasms was targeted. A restriction pattern of a previously unreported piroplasm was observed. The PCR product was sequenced, and the sequence obtained had 99% identity with the Rangelia vitalii sequences from Brazil when compared by BLAST analysis. Further characterization of the detected piroplasm consisted of nearly full-length sequencing (1668 bp) of the 18S rRNA gene of this organism. Those sequences were deposited in GenBank. A phylogenetic analysis indicated that they clustered together with R. vitalii from Brazil but separately from large Babesia species of dogs such as Babesia canis, and from species of Theileria of dogs as well. This is the first report of R. vitalii infection in Argentina, and the first case of canine rangeliosis diagnosed outside Brazil.     

Theileria gilberti n. sp. (Apicomplexa: Theileriidae) in the Gilbert's Potoroo (Potorous gilbertii)

ABSTRACT. The morphology and genetic characterisation of a new species of piroplasm identified in the blood of the Gilbert's potoroo ( Potorous gilbertii ) from the Two Peoples Bay Nature Reserve near Albany, Western Australia, is described from blood and tissue samples from 16 Gilbert's potoroos. Microscopy of blood showed these parasites are highly pleomorphic with a mean length of 1.8 μm and mean width of 0.85 μm. Phylogenetic analysis of 18S rRNA sequence data identified the piroplasm as a new species of Theileria that is closely related to other Australian marsupial piroplasm species. Based on biological and molecular data, it is proposed that the parasite from Gilbert's potoroo be given the name Theileria gilberti n. sp.     

Babesia leo n. sp. from lions in the Kruger National Park, South Africa, and its relation to other small piroplasms.

Babesia leo, a small piroplasm isolated from lions in South Africa is described as a distinct species based on a phylogenetic analysis of the 18S rRNA gene. Intraerythrocytic trophozoite and merozoite stages of B. leo are morphologically indistinguishable from other small piroplasms of felids. Previous studies showed that B. leo was biologically and antigenically distinct from B. felis, which is known to infect wild and domestic felids in South Africa. Molecular characterization showed strong support for the phylogenetic seperation of B. leo as a distinct species from B. felis and other felid piroplasms. Phylogenetic analysis also showed that Babesia microti and all of the felid piroplasms from Africa with known 18S rRNA gene sequences available, including B. leo, formed a single, separate clade, sister to the other babesial and theilerial piroplasm parasites.     

Cattle and small ruminant piroplasmosis in Macedonia, Greece

Macedonia is an endemic region of cattle as well as of sheep and goat piroplasmosis In cattle, Theileria orientalis (=T. buffeli?), the agent of Eurasian benign theileriosis, is the most common and widespread piroplasm species. T. annulata, the agent of tropical theileriosis, seems to be rare and limited to few foci, but causes very severe clinical cases, especially in imported pure-bred or cross-bred animals. Babesia bovis and B. bigemina are present in several localities, and often coexist. Cattle babesiosis cases are due to both piroplasms, but B. bovis is considered responsible for the severe and acute clinical cases. Ovine and caprine babesiosis is due to B. ovis and mainly affected imported animals as well as indigenous animals which have been transported from localities where the infection was absent. B. ovis is extremely widespread in both sheep and goats. During the last decades, no clinical cases of small ruminant theileriosis have been registered in this region. However, T. ovis, a non-pathogenic theileria, is common in sheep, but not in goats. Anaplasma ovis, a protobacterium of small ruminants, is also present in the region.     

Molecular characterization of Babesia kiwiensis from the brown kiwi (Apteryx mantelli)

To further investigate the recently described avian piroplasm, Babesia kiwiensis, blood samples were collected from 13 wild-caught and 8 zoo-captive brown kiwi (Apteryx mantelli) and screened for the presence of piroplasm DNA using a nested-polymerase chain reaction (PCR) targeting the 18S rRNA gene of most members of Piroplasmida. All captive birds gave a negative PCR result, while 12 wild-caught birds were PCR positive. The nearly full-length 18S rRNA gene for B. kiwiensis was sequenced. Upon phylogenetic analysis, it was found to belong to the babesid group of piroplasms and was ancestral, yet genetically similar, to the Babesia canis-related species. An insight into the current taxonomy of the avian piroplasms is also given. An Ixodes anatis tick collected from 1 of the North Island brown kiwi was also screened using PCR and was found to be positive for B. kiwiensis DNA.     

Neoparamoeba perurans n. sp., an agent of amoebic gill disease of Atlantic salmon (Salmo salar)

Amoebic gill disease (AGD) is a potentially fatal disease of some marine fish. Two amphizoic amoebae Neoparamoeba pemaquidensis and Neoparamoeba branchiphila have been cultured from AGD-affected fish, yet it is not known if one or both are aetiological agents. Here, we PCR amplified the 18S rRNA gene of non-cultured, gill-derived (NCGD) amoebae from AGD-affected Atlantic salmon (Salmo salar) using N. pemaquidensis and N. branchiphila-specific oligonucleotides. Variability in PCR amplification led to comparisons of 18S rRNA and 28S rRNA gene sequences from NCGD and clonal cultured, gill-derived (CCGD) N. pemaquidensis and N. branchiphila. Phylogenetic analyses inferred from either 18S or 28S rRNA gene sequences unambiguously segregated a lineage consisting of NCGD amoebae from other members of the genus Neoparamoeba. Species-specific oligonucleotide probes that hybridise 18S rRNA were designed, validated and used to probe gill tissue from AGD-affected Atlantic salmon. The NCGD amoebae-specific probe bound AGD-associated amoebae while neither N. pemaquidensis nor N. branchiphila were associated with AGD-lesions. Together, these data indicate that NCGD amoebae are a new species, designated Neoparamoeba perurans n.sp. and this is the predominant aetiological agent of AGD of Atlantic salmon cultured in Tasmania, Australia.     

Theileria ovis discovered in China

A polymerase chain reaction (PCR) using 989/990 primers was conducted to identify a newly isolated Theileria sp. in Xinjiang Province of China. The target DNA fragments of the complete 18S rRNA gene were cloned and sequenced. The phylogenetic relationship of newly isolated Theileria spp. was inferred based on the 18S rRNA gene. The results showed that the new Theileria sp. belonged to the cluster of Theileria ovis. Moreover, the findings were confirmed by T. ovis species-specific PCR. An expected 520 bp fragment of T. ovis DNA was obtained from 25 out of 320 (8%) field blood samples, and blood of an experimental sheep infested by Hyalomma anatolicum anatolicum collected in Xinjiang. The infection rate of T. ovis was 78% (25/32) in Xinjiang province. The investigation did not find T. ovis positive samples from the field samples collected from the other twelve provinces. This study indicates that T. ovis is prevalent in Xinjiang province of China and its transmission vector is H. anatolicum anatolicum.     

Identification of a 40S Ribosomal protein (S17) that is differentially expressed between the macroschizont and piroplasm stages of Theileria annulata.

The nucleotide and protein sequence of the 40S ribosomal protein S17 (RibS17) of the protozoan parasite Theileria annulata has been determined. Southern blot analysis showed the gene was single copy and comparative sequence analysis revealed that the predicted polypeptide had high sequence homology with the RibS17 from other organisms. Northern blot analysis showed that there was a 3-fold increase in the level of RibS17 RNA between the macroschizont and the piroplasm stage of the lifecycle, whereas, there was no difference in expression between the sporozoite and the macroschizont stages. Antisera to the purified fusion protein, corresponding to the terminal 50 amino acids of the protein sequence, were raised in rabbits. Western analysis detected a polypeptide of the predicted size that was more abundant in the piroplasm stage compared with the macroschizont stage. Immunofluorescence analysis with the same antisera revealed a strong signal in the macroschizont and piroplasm stages, but the antiserum did not cross-react with the bovine host cells. The antisera did, however, cross-react with Toxoplasma gondii tachyzoites and Plasmodium falciparum merozoites. The possible functional significance of the stage related increase in abundance of a ribosomal protein is discussed.