Genetic diversity of emerging hemotropic mycoplasmas in domestic pigs from Brazil

Hemotrophic Mycoplasmas-Vector Transmission in Livestock

Hemotrophic mycoplasmas (HMs) are highly host-adapted and specialized pathogens infecting a wide range of mammals including farm animals, i.e., pigs, cattle, sheep, and goats. Although HMs have been known for over 90 years, we still do not know much about the natural transmission routes within herds. Recently, it has been repeatedly discussed in publications that arthropod vectors may play a role in the transmission of HMs from animal to animal. This is mainly since several HM species could be detected in different potential arthropod vectors by PCR. This review summarizes the available literature about the transmission of bovine, porcine, ovine, and caprine HM species by different hematophagous arthropod vectors. Since most studies are only based on the detection of HMs in potential vectors, there are rare data about the actual vector competence of arthropods. Furthermore, there is a need for additional studies to investigate, whether there are biological vectors in which HMs can multiply and be delivered to new hosts.

Haemotrophic Mycoplasmas Infecting Pigs: A Review of the Current Knowledge

Haemotrophic mycoplasmas (haemoplasmas) are a group of highly specific and adapted bacteria. Three different haemoplasma species in pigs are known to date: Mycoplasma (M.) suis, M. parvum and 'Candidatus (Ca.) M. haemosuis'. Even though these bacteria have been known in pig farming for a long time, it is difficult to draw general conclusions about the relevance of their infections in pigs. This review summarizes the current knowledge on the three porcine haemoplasma species with regards to clinical and pathological descriptions, pathobiology, epidemiology and diagnostics as well as prevention and therapy. Overall, it is clear that considerably more data are available for M. suis than for the other two species, but generally, porcine haemoplasmas were found to be highly prevalent all over the world. Mycoplasma suis is the most virulent species, causing acute infectious anaemia in pigs (IAP), whereas M. parvum usually results in chronic and subclinical infections associated with performance losses. Little is known about the clinical significance of the recently discovered third porcine species 'Ca. M. haemosuis'. So far, the described pathogenic mechanisms mainly include direct destruction of erythrocytes via adhesion, invasion, eryptosis and nutrient scavenging, indirect erythrocyte lysis due to immune-mediated events and immune dysregulation processes. A review of published diagnostic data confirms PCR assays as the current standard method, with various cross-species and species-specific protocols. Overall, there is a need for further examination to obtain valuable insights for practical application, specifically regarding the importance of subclinical infections in naturally infected animals. An essential requirement for this will be to gain a more comprehensive understanding of the mechanisms operating between the host and the pathogen.

A real-time PCR assay for the quantification of Mycoplasma equirhinis in tracheal wash samples from Thoroughbred horses

Mycoplasma equirhinis is the predominant equine Mycoplasma sp. isolated from clinically normal horses and is suspected to be associated with inflammatory airway disease in which cough is the primary sign. Quantitative evaluation of bacterial counts is useful in assessing the association between the bacteria in samples and observed clinical signs, but this evaluation has been difficult with conventional culture methods of M. equirhinis given the need for pre-enrichment using liquid cultures. We established a quantitative real-time PCR (qPCR) assay for the quantification of M. equirhinis, targeting the hypothetical protein FJM08_00025. We confirmed its high species-specificity for M. equirhinis and a limit of detection of 2.9 copies/reaction. We quantified M. equirhinis in tracheal wash samples from 20 clinically normal horses and 22 coughing horses. The copy numbers detected by qPCR in 18 of the 22 samples from clinically affected horses were within the range detected in the 20 clinically normal horses (0-84 copies/reaction). The remaining 4 samples had considerably higher copy numbers (734-1,620,000 copies/reaction), suggesting the likely involvement of M. equirhinis infection. Quantitative evaluation of M. equirhinis over time using our qPCR assay may allow a more accurate assessment of M. equirhinis infection in coughing horses compared to culture methods.

Molecular Survey of Hemotropic Mycoplasma spp. and Bartonella spp. in Coatis (Nasua nasua) from Central-Western Brazil

Even though previous works showed molecular evidence of hemotropic Mycoplasma spp. (hemoplasmas) in ring-tailed coatis (Nasua nasua) from Brazil, Bartonella sp. has not been reported in these mammals so far. The present study aimed to detect the above-mentioned agents in coatis’ blood and associated ectoparasites, assessing the association between these infections and red blood parameters. Between March 2018 and January 2019, coati (n = 97) blood samples, Amblyomma sp. ticks (2242 individual ticks, resulting in 265 pools), and Neotrichodectes pallidus louse (n = 59) were collected in forested urban areas from midwestern Brazil. DNA extracted from coatis’ blood, and ectoparasite samples were submitted to quantitative PCR (qPCR) (16S rRNA) and conventional PCR (cPCR) (16S rRNA and 23S rRNA) for hemoplasmas and qPCR (nuoG gene) and culturing (only blood) for Bartonella spp. Two different hemoplasma genotypes were detected in blood samples: 71% coatis positive for myc1 and 17% positive for myc2. While 10% of ticks were positive for hemoplasmas (myc1), no louse was positive. The estimated bacterial load of hemoplasmas showed no association with anemia indicators. All coatis were negative for Bartonella sp. in qPCR assay and culturing, albeit two Amblyomma sp. larvae pools, and 2 A. dubitatum nymph pools were positive in the qPCR. The present work showed a high occurrence of hemoplasmas, with two distinct hemoplasma genotypes, in coatis from forested urban areas in midwestern Brazil.

Co-infection by multiple vector-borne agents in wild ring-tailed coatis (Nasua nasua) from Iguaçu National Park, southern Brazil

The present study aimed to detect molecularly the presence of co-infections by vector-borne agents (VBA) in ring-tailed coatis' (Nasua nasua) blood samples from Iguaçu National Park (INP), southern Brazil, and assess the phylogenetic positioning of the detected agents. DNA blood samples were submitted to molecular screening and characterization for Anaplasmataceae agents, Piroplasmids, Hepatozoon sp., hemotropic mycoplasmas, and Bartonella spp. In total, 42 (85.7%) coatis were positive for hemotropic Mycoplasma sp., 12 (24.5%) for Bartonella machadoae, 7 (14.3%) for Anaplasma sp. closely related to 'Candidatus Anaplasma brasiliensis', and 3 (6%) for Hepatozoon procyonis. The most prevalent co-infections observed was from bacterial VBA: while 18.3% were co-infected by hemotropic Mycoplasma sp. and Bartonella sp., 12.2% were co-infected by Anaplasma sp. and hemotropic Mycoplasma sp. Only two animals (4%) presented co-infections by three VBA (Bartonella sp., Anaplasma sp. and hemotropic Mycoplasma sp.). The coati is a wild carnivore found in INP, mainly in areas visited by tourists. These animals are frequently seen searching for food in garbage dumps or in tourists' belongings. The present study expands the host specificity range of B. machadoae, which has been isolated only from rodents until the present moment. Since the zoonotic potential and transmission routes of the detected VBA are not yet known, surveillance in this area is much needed.

Molecular prevalence of Mycoplasma parvum in production cycle of technified swine herds

ABSTRACT Porcine hemoplasmosis is characterized as a geographically cosmopolitan disease caused by Mycoplasma suis and Mycoplasma parvum. Asymptomatic pigs are considered the focus of hemoplasmosis because they are carriers and reservoirs to new infections. This study aimed to determine the molecular occurrence of porcine hemoplasmas (PH) in the production cycle of technified farrow-to-finished swine herds. For this purpose, 20 swine herds were evaluated, where 501 whole blood samples were collected for qPCR and phylogenetic analyses for hemoplasmas. The epidemiological analysis was performed for the entire population and per the growth stage. The total prevalence for PH was 31.93% (161/501); 95% (19/20) of sampled herds were positive. The occurrence of PH by swine growth stages was nursery (30.47%), growing (31.29%), finishing (26.18%), and slaughter (40.25%). The quantification cycles (Cq) ranged from 3.18- 39.56 and the number of PH 16S rRNA copies per µL of DNA ranged from 5,57 x10-2 to 2.23 x1010. Sequencing and phylogenetic analysis of five selected samples showed 100% identity with M. parvum strain Indiana and two M. parvum sequences from Brazil/Goiás. This is the first report on PH in technified herds in Southeastern Brazil by growth stages.

Occurrence of Mycoplasma parvum in German Pigs of Different Age Groups Using a Novel Quantitative Real-Time PCR Assay

Mycoplasma (M.) parvum is a hemotrophic bacterium circulating in the blood of pigs but is not considered a primary pathogen. Only a handful of studies dealing with this agent have been published since its first description in 1951, and many issues, including epidemiology and the impact of subclinical infections, are yet to be elucidated. This study aimed to establish a M. parvum specific real-time PCR for its detection and quantification in porcine blood and the application of this assay to obtain insights into the occurrence of M. parvum in German pigs. Furthermore, 16S rDNA amplicons of M. parvum positive blood samples were phylogenetically analyzed using MEGA 11 software. The established qPCR targeting the M. parvum glyceraldehyde-3-phosphate dehydrogenase encoding gene (gap) showed a lower detection limit of 10 gene copies per reaction and no cross-reactivity within the specificity test. A total of 36.0% (n = 72) of the sampled fattening pigs, 25.0% (n = 15) of the sows, and 4.37% (n = 8) of the boars tested M. parvum positive. The dendrogram showed the typical allocation of the M. parvum isolates into the "haemominutum group" subgroup within the hemotrophic Mycoplasma species. Both the novel established qPCR and the obtained epidemiological data can serve as an important basis for future studies dealing with M. parvum.

Molecular detection of vector-borne agents in wild boars (Sus scrofa) and associated ticks from Brazil, with evidence of putative new genotypes of Ehrlichia, Anaplasma and hemoplasmas

The present study aimed to investigate, by molecular techniques, the occurrence of Anaplasmataceae, Bartonellaceae, Rickettsiaceae, Mycoplasmataceae, Coxiellaceae e Babesiidae/Theileriidae agents in blood samples of free-living wild boars (Sus scrofa) and associated ticks in southeastern Brazil. For this purpose, 67 blood samples and 265 ticks (264 Amblyomma sculptum and one A. ovale) were analyzed. In the screening for Anaplasmataceae agents by a PCR assay based on the 16S rRNA gene, 5.97% blood samples and 50.54% ticks were positive. In the PCR assay for Ehrlichia spp. based on the dsb gene, 9.24% of ticks were positive. Despite the low occurrence, a possible new 16S rRNA genotype of Anaplasma sp. was detected in a wild boar's blood sample. According to phylogenetic analyses based on the groEL, gltA, sodB genes and ITS (23S-5S rRNA) intergenic region, it was found that A. sculptum and A. ovale ticks collected from wild boars carry Ehrlichia genotypes phylogenetically associated with E. ewingii, E. ruminantium, and new Ehrlichia genotypes previously detected in horses, peccaries, and ticks collected from jaguars. In the screening for hemoplasmas by a qPCR based on the 16S rRNA gene, 88.06% of blood samples and 8.69% of ticks were positive. Mycoplasma suis, M. parvum and a possible new hemoplasma genotype were detected in wild boars in southeastern Brazil. In the screening for Bartonella spp. using a nuoG-based qPCR assay, 3.8% of tick samples were positive. Phylogenetic inferences positioned four nuoG and one r gltA Bartonella sequences into the same clade as Bartonella machadoae. No blood or tick samples from wild boars showed to be positive in the qPCR for Coxiella burnetii based on the IS1111 gene. On the other hand, only 1.6% of ticks was positive in the nested PCR assay for piroplasmids based on the 18S rRNA gene. A 18S rRNA sequence detected in a pool of A. sculptum nymphs was phylogenetically close to Cytauxzoon felis sequences previously detected in cats from the United States. Rickettsia sp. closely related to R. bellii was detected in a pool of A. sculptum nymphs. This is the first report of hemoplasmas, B. machadoae and Cytauxzoon spp. in A. sculptum. Wild boars and associated ticks do not seem to participate in the epidemiological cycle of C. burnetii in the region studied. This invasive mammal species may act as a potential disperser of ticks infected with Ehrlichia spp., Bartonella spp., hemotropic mycoplasmas, and Cytauxzoon, and may bring important epidemiological implications in the transmission of bartonelosis, ehrlichiosis, hemoplasmosis, and cytauxzoonosis to humans and animals, more specifically to horses, rodents, pigs, and cats. This article is protected by copyright. All rights reserved.

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.

Molecular detection and genetic analysis of porcine hemoplasmas in commercial pig farms from Thailand reveal a putative novel species

Hemoplasma is a trivial name for hemotropic Mycoplasma spp., which can attach to the surface of red blood cells leading to deformity and anemia in a wide range of mammalian animals, including pigs. In Thailand, there is only one study that reported the occurrence of Mycoplasma suis without other hemoplasma species. In this study, we examined the molecular occurrence and genetic diversity of porcine hemoplasmas in Thai domestic pigs (Sus scrofa domesticus) from commercial farms using a PCR assay targeting the 16S rRNA gene, DNA sequencing, nucleotide sequence type (ntST) analysis, and phylogenetic analysis. A total of 665 blood samples were collected from pigs at thirteen farms located in eight provinces of Thailand during 2019-2020. Genomic DNA was extracted from blood samples and tested by PCR. The frequency of hemoplasma infection was 37.1% (247/665, 95% CI: 33.5%-40.9%) in all pigs. Among 247 PCR positive samples, 194 were sequenced and analyzed by nucleotide BLAST, ntST diversity, phylogenetic trees, and ntST networks. The results of this genetic analysis indicated that at least four species with 27 nucleotide sequence types (Mycoplasma suis, Mycoplasma parvum, Candidatus Mycoplasma haemosuis, and a putative novel species) of porcine hemoplasmas were identified. Thus, it appears that hemoplasmas show a high genetic diversity in the Thai pig population. In addition, a putative novel species was genetically characterized by other markers, namely the 23S rRNA and RNase P RNA (rnpB) genes. For phylogenetic analysis, Candidatus Mycoplasma haemosuis was placed into the Mycoplasma haemofelis group, and the three remaining species were placed into the Mycoplasma suis group in all trees containing the 16S rRNA, 23S rRNA, and rnpB genes. Further studies, such as pathobiology and epidemiology, should be conducted to better characterize this putative novel species. This article is protected by copyright. All rights reserved.

Porcine hemothropic mycoplasmas infection associated with productive impact in intensive pig production

Background

So far, three porcine hemoplasmas (PH) have been identified, namely Mycoplasma suis, Mycoplasma parvum, and Mycoplasma haemosuis. The first one is the main agent associated with porcine hemoplasmosis, a possible cause of economic losses in pig production. Thus, this work aimed to detect and quantify PH 16S rRNA in finishing pigs and to associate its load estimate with average daily weight gain (ADWG). For this purpose, whole blood samples from 318 pigs were collected at an age of 75 days (d0) when the pigs entered the finishing phase and 105 days later (d105). To calculate ADWG, the animals were weighed at the abovementioned dates. Then, DNA from blood samples were submitted to a qPCR targeting the 16S rRNA gene for PH. Spearman correlation test was performed to investigate potential associations between ADWG and the quantification values. Lastly, the molecular characterization of PH was done by sequencing the 23S rDNA gene.

Results

Out of the 318 samples, 190 (59.74%) were positive on d0, and 304 (95.6%) were positive on d105. A significant correlation was observed (p < 0.05), albeit with a low coefficient value (0.18), when comparing ADWG with quantification values on d105. The phylogenetic analysis based on the 23S rDNA gene showed that four sequences were closely related to M. parvum, and one sequence was positioned in the M. suis cluster.

Conclusion

Two PH, M. suis and M. parvum, were detected in a Brazilian pig farm. Moreover, increasing occurrence through time was observed, which may have affected the productive performance of positive animals, mainly at the end of the finishing phase, when antimicrobials are removed.

Supplementary information

The online version contains supplementary material available at 10.1186/s40813-020-00171-1.