Occurrence of hemotrophic mycoplasmas in horses with correlation to hematological findings

First molecular detection of Mycoplasma ovis in horses from Brazil

This study aimed to determine the occurrence of hemoplasmas and tick-borne pathogens (TBP) (Theileria equi, Babesia caballi, and Ehrlichia sp.) in horses and ticks' salivary glands, and determine the factors associated with exposure/infection in a rural settlement in southern Brazil. Blood samples from 22 horses were screened for anti-T. equi and anti-Ehrlichia sp. antibodies by an indirect fluorescent antibody test (IFAT) assays. Samples were also tested by PCR assays for T. equi and B. caballi (18S rRNA and rap-1 genes, respectively), hemoplasmas (16S rRNA gene), and Ehrlichia sp. (dsb gene). Ticks were removed from the animals (inspection) and the environment (flannel trawling and dry ice traps), and morphologically identified. Additionally, salivary glands DNA was extracted from 28 adult ticks infesting the animals and four nymphs from the environment, and further screened for Ehrlichia sp. and hemotropic Mycoplasma sp. Anti-T. equi and anti-Ehrlichia sp. antibodies were detected in 40.91% (nine/22; 95% CI: 23.26-61.27) and 31.81% (seven/22; 95% CI: 16.36-52.68) horses, respectively. Theileria equi, B. caballi, and hemotropic Mycoplasma sp. DNA was detected in 59.09% (13/22), 4.55% (one/22), and 50% (11/22) horses, respectively. All horses tested negative in the PCR for Ehrlichia sp. All sequences showed ≥99% identity with multiple T. equi, B. caballi, and Mycoplasma ovis sequences deposited in GenBank database. Adult ticks were identified as Dermacentor nitens (44/47; 93.62%) and Rhipicephalus microplus (three/47; 6.38%). Ticks' salivary glands were negative for Ehrlichia sp., while 39.29% from adults (11/28) and 50% from nymphs (two/four) from the environment were positive for hemotropic Mycoplasma sp. This is the first report of M. ovis infection in horses from Brazil and the first detection of hemoplasma DNA in salivary glands of D. nitens and R. microplus ticks. Further studies are needed to elucidate the vector competence of ticks to transmit hemoplasmas.

Mycoplasmas as Host Pantropic and Specific Pathogens: Clinical Implications, Gene Transfer, Virulence Factors, and Future Perspectives

Mycoplasmas as economically important and pantropic pathogens can cause similar clinical diseases in different hosts by eluding host defense and establishing their niches despite their limited metabolic capacities. Besides, enormous undiscovered virulence has a fundamental role in the pathogenesis of pathogenic mycoplasmas. On the other hand, they are host-specific pathogens with some highly pathogenic members that can colonize a vast number of habitats. Reshuffling mycoplasmas genetic information and evolving rapidly is a way to avoid their host's immune system. However, currently, only a few control measures exist against some mycoplasmosis which are far from satisfaction. This review aimed to provide an updated insight into the state of mycoplasmas as pathogens by summarizing and analyzing the comprehensive progress, current challenge, and future perspectives of mycoplasmas. It covers clinical implications of mycoplasmas in humans and domestic and wild animals, virulence-related factors, the process of gene transfer and its crucial prospects, the current application and future perspectives of nanotechnology for diagnosing and curing mycoplasmosis, Mycoplasma vaccination, and protective immunity. Several questions remain unanswered and are recommended to pay close attention to. The findings would be helpful to develop new strategies for basic and applied research on mycoplasmas and facilitate the control of mycoplasmosis for humans and various species of animals.

The occurrence of hemotropic Mycoplasma ovis-like species in horses

Hemotropic mycoplasmas (haemoplasmas) are wall-less bacteria, which may lead to anemia and, even, mortality in mammals. The present study was aimed to characterize the causative agent(s) of haemoplasma infection in blood samples taken from horses (n = 133) in south of Iran. Microscopic examination of blood smears and PCR assay were performed for the detection of hemotropic Mycoplasma and equine piroplasma (Babesia caballi and Theileria equi). For the purpose of molecular characterization, 16S rDNA and 18S rDNA markers were used for hemotropic Mycoplasma and piroplasma pathogens, respectively. The PCR-positive samples were sequenced for haemoplasma and further phylogenetic analysis was performed for the obtained haemoplasma sequences. Nine out of 133 (6.77 %, 95 % CI: 2.5-11.04 %) horses were positive for Mycoplasma sp. by PCR. Furthermore, three of these animals were co-infected with T. equi. Interestingly, the phylogenetic and molecular analysis of the haemoplasma sequences derived from the PCR amplicons in the equine positive cases showed 100 % identity with 16S rDNA in Mycoplasma ovis, an HM member mainly found in sheep and goats. In addition, the hematological analysis showed that PCR positive horses for M. ovis-like species had a lower hematocrit (Hct), hemoglobin (Hb) concentration, and red blood cell (RBC) count compared to the PCR negative ones (P ≤ 0.05). Mild anemia was also developed in the haemoplasma-positive horses. These findings represent the first molecular evidence of M. ovis-like species in horses. Further experimental studies are needed to examine the importance of this nonspecific host infection and evaluate its pathogenicity in equine and other species.

Molecular identification of vector-borne organisms in Ehrlichia seropositive Nicaraguan horses and first report of Rickettsia felis infection in the horse

Certain vector-borne organisms serve as etiological agents of equine disease. After previously identifying a new Ehrlichia species in horses from Mérida, we aimed to determine the infection frequency and screen for a wide range of vector-borne organisms from 93 tick-exposed, Ehrlichia seropositive horses in this region. PCR assays were performed to identify infection by organisms within the following genera: Anaplasma, Babesia, Bartonella, Ehrlichia, Leishmania, Mycoplasma, Neorickettsia, Rickettsia and Theileria. Overall, 90/93 horses (96.8%) were infected with one or more vector-borne organisms. Ninety (96.8%) horses were infected with Theileria equi and 21 (26.8%) with Babesia caballi. Nine (9.7%) horses were infected with the novel Ehrlichia species previously designated H7, reported in horses from Nicaragua and Brazil. Two horses (2.2%) were infected with Rickettsia felis. Anaplasma, Bartonella, Leishmania, Mycoplasma, or Neorickettsia species DNA was not amplified from any horse. Ticks collected from horses infected with vector-borne organisms were identified as Amblyomma cajennense sensu lato and Dermacentor nitens. Horses in Mérida are infected by a range of vector-borne organisms, including B. caballi, T. equi, Ehrlichia species H7, and R. felis. To the authors' knowledge, this constitutes the first report of molecular detection of R. felis in horses.

Tick-borne pathogens in carthorses from Foz do Iguaçu City, Paraná State, southern Brazil: A tri-border area of Brazil, Paraguay and Argentina

Tick-borne diseases (TBD) constitute an important group of illness affecting animals and humans worldwide. In Brazil, carthorses are frequently exposed to ticks and tick-borne pathogens, leading to impairment of horse performance and imposing restrictions by the international veterinary authorities for the importation of horses. Accordingly, this study has aimed to i) determine the prevalence of the TBD agents Theileria equi, Babesia caballi, Ehrlichia spp., and hemotropic mycoplasmas in carthorses, ii) identify the tick species parasitizing the animals, and iii) determine factors associated with exposure/infection in Foz do Iguaçu City, Parana state, southern Brazil. A total of 103 carthorses were screened for anti-T. equi and anti-Ehrlichia spp. antibodies by indirect fluorescent antibody assays (IFA). Samples were also tested by PCR assays targeting the 18S rRNA gene of T. equi and B. caballi, and 16S rRNA gene of hemoplasmas. Additionally, PCR assays targeting the 16S rRNA, disulfide bond formation protein (dsb) and tandem repeat proteins 36 (trp36) genes of Ehrlichia spp. were also performed. Antibodies to T. equi and Ehrlichia spp. were detected in 43/103 (41.75%; 95% CI: 32.10-51.88%) and 5/103 (4.85%; 95% CI: 1.59-10.97%) horses by IFA, respectively. DNA of T. equi and B. caballi were found in 25/103 (24.27%; 95% CI: 16.36-33.71%) and 10/103 (9.71%; 95% CI: 4.75-17.13%) carthorses, respectively, and all tested negative for Ehrlichia spp. and hemoplasmas. All sequences showed ≥99% identity with multiple T. equi and B. caballi 18S rRNA gene sequences deposited in GenBank. Overall, 191 Dermacentor nitens ticks were collected from 25/103 (24.27%) animals. Carthorses older than 5 years were more likely to be positive for T. equi (p < 0.05). In conclusion, equine piroplasmosis agents are highly prevalent in carthorses from Foz do Iguaçu City. The low prevalence of Ehrlichia spp. found may be due to the absence of Amblyomma ticks infesting animals, which should be further investigated.

Prevalence, Genotype Richness, and Coinfection Patterns of Hemotropic Mycoplasmas in Raccoons (Procyon lotor) on Environmentally Protected and Urbanized Barrier Islands

Raccoons (Procyon lotor) are successful urban adapters and hosts to a number of zoonotic and nonzoonotic pathogens, yet little is known about their hemoplasma infections and how prevalence varies across habitat types. This study identifies hemotropic Mycoplasma species infection in raccoons from urban and undisturbed habitats and compares hemoplasma infection in sympatric urban cats (Felis catus) from the same geographic region. We collected blood from raccoons (n = 95) on an urban coastal island (n = 37) and an undisturbed coastal island (n = 58) and from sympatric urban cats (n = 39) in Georgia, USA. Based on 16S rRNA gene amplification, 62.1% (59/95) of raccoons and 17.9% (7/39) of feral cats were positive for hemoplasma. There was a greater percentage of hemoplasma-infected raccoons on the undisturbed island (79.3% [46/58]) than on the urban island (35.1% [13/37]; χ2 = 16.9, df = 1, P = 0.00004). Sequencing of the full-length 16S rRNA gene amplicons revealed six hemoplasma genotypes in raccoons, including five novel genotypes that were distinct from three known hemoplasma species identified in the sympatric cats. In addition, the hemoplasma genotypes detected in raccoons were not identified in sympatric cats or vice versa. Although all six hemoplasma genotypes were found in raccoons from urban and undisturbed islands, coinfection patterns differed between sites and among individuals, with the proportion of coinfected raccoons being greater in the undisturbed site. This study shows that raccoons are hosts for several novel hemoplasmas and that habitat type influences infection patterns.IMPORTANCE This study provides information about novel hemoplasmas identified in raccoons (Procyon lotor), which can be used for assessments of the prevalence of these hemoplasmas in raccoon populations and for future studies on the potential pathogenic impacts of these hemoplasmas on raccoon health. Raccoons from the undisturbed habitat had a higher prevalence of hemoplasma infection than urban raccoons. There does not appear to be cross-species transmission of hemotropic mycoplasmas between urban raccoons and feral cats. Raccoons appear to be hosts for several novel hemoplasmas, and habitat type influences infection patterns.

Serological and molecular detection of Theileria equi in sport horses of northeastern Brazil

Theileriosis is a worldwide protozoal tick-borne disease caused by Theileria equi, which may produce a variety of clinical signs and turn infected horses into lifetime carriers. This study has aimed to perform a serological and molecular detection of T. equi and associated factors in sports horses from six areas of northeastern Brazil. In overall, 59.6% horses were positive by indirect immunofluorescence assay and 50.4% by polymerase chain reaction. No significant association was found when presence of ticks, age, gender, anemia or total plasma proteins was analyzed with seropositivity and molecular techniques. Although a significant association of infection was found in two cities. Thus, local risk factors other than presence of ticks, horse age, gender, anemia and total plasmatic proteins may dictate prevalence of T. equi infection in sports horses, even in highly endemic areas with no control of infection prior to horse competitions.

MOLECULAR INVESTIGATION OF HEMOTROPIC MYCOPLASMAS IN HUMAN BEINGS, DOGS AND HORSES IN A RURAL SETTLEMENT IN SOUTHERN BRAZIL

The aims of this study were to determine the prevalence of hemoplasmas in a rural Brazilian settlement's population of human beings, their dogs and horses, highly exposed to tick bites; to identify the tick species parasitizing dogs and horses, and analyze factors associated with their infection. Blood samples from 132 dogs, 16 horses and 100 humans were screened using a pan-hemoplasma SYBR green real-time PCR assay followed by a species-specific TaqMan real-time PCR. A total of 59/132 (44.7%) dog samples were positive for hemoplasmas (21 Mycoplasma haemocanisalone, 12 ' Candidatus Mycoplasma haematoparvum' alone and 21 both). Only 1/100 (1.0%) human sample was positive by qPCR SYBR green, with no successful amplification of 16S rRNA or 23 rRNA genes despite multiple attempts. All horse samples were negative. Dogs >1 year of age were more likely to be positive for hemoplasmas ( p= 0.0014). In conclusion, although canine hemoplasma infection was highly prevalent, cross-species hemoplasma transmission was not observed, and therefore may not frequently occur despite overexposure of agents and vectors.

Occurrence and identification of hemotropic mycoplasmas (Hemoplasmas) in free ranging and laboratory rats (Rattus norvegicus) from two Brazilian zoos

BACKGROUND

Hemotropic mycoplasmas (hemoplasmas), bacteria belonging to the class Mollicutes, are obligatory red blood cell pathogens of a variety of animal species. They may cause acute anemia that is life-threatening or chronic disease that is clinically silent, but may interfere with results of experimental studies when using infected animals. Since these bacteria cannot be cultivated, molecular techniques are the gold standard for diagnosing an infection, investigating its prevalence, and describing new species. Mycoplasma coccoides and M. haemomuris are the most commonly recognized hemoplasmas in the blood of wild and laboratory rodents. Neither the epidemiology nor clinical and molecular characterization of hemoplasma infection in free-ranging rodents in Brazil has been previously reported. The aims of this study were to investigate the occurrence of hemoplasmas in free-ranging rats (Rattus norvegicus) captured in the Passeio Público and Curitiba Zoo and compare hematologic parameters of infected and non-infected animals.

RESULTS

Anti-coagulated blood samples collected from 43 free-ranging and 20 nursery rats were included in the study. Overall 63.5% were positive using SYBR® Green quantitative PCR (qPCR) of the 16S rRNA gene to screen for hemoplasma infection (72% among free-ranging rats; 45% among laboratory-raised rats). Sequencing of the qPCR products showed that all but one sample had >98% identity to M. haemomuris. Phylogenetic analysis based on a fragment of approximately 1300 bp of the 16S rRNA gene showed 99% identity to a new hemoplasma from European rats and 98% identity to a hemotropic mycoplasma described infecting a European harvest mouse (Micromys minutus). No statistically significant changes in hematologic parameters between infected and non-infected rats were found, confirming the low pathogenicity and/or silent characteristics of the infection.

CONCLUSIONS

Our findings suggest that hemoplasmas are likely endemic in rodent species in this region. The epidemiology, especially as it relates to the mode of transmission, needs to be further investigated as well as the possibility that other animal species, including humans, might become infected.