Development and application of a real-time TaqMan® qPCR assay for detection and quantification of ‘Candidatus Mycoplasma haemolamae’ in South American camelids

Anaemia in South American camelids - an overview of clinical and laboratory diagnostics

South American camelids (SACs) play an increasing role in veterinary care in Europe. Many alpacas or llamas presented to veterinarians suffer from anaemia, regularly with a packed cell volume (PCV) below 0.10 l/l, which is a life-threatening condition for the animals. This review article presents clinical and laboratory diagnostic tools for the diagnosis of anaemia in SACs. Clinical identification of anaemic animals can be performed by assessing the FAMACHA© score and the Body Condition Score (BCS), since anaemia in alpacas and llamas correlates with pale mucous membranes and a lowered BCS. Haematological examination of a blood sample can provide a more differentiated diagnosis of anaemia in SACs. A common finding is regenerative anaemia with an increased number of reticulocytes that is often caused by blood loss due to Haemonchus contortus. Changes in a blood smear from an alpaca or llama with regenerative anaemia may include normoblasts (nucleated red blood cells), anisocytosis, poikilocytosis, polychromasia, Howell-Jolly bodies or basophilic stippling. Furthermore, non-regenerative anaemia, often caused by trace element deficiency or cachexia, can also occur.

Molecular survey of hemoplasmas in asymptomatic vicunas (Vicugna vicugna) from the Pampa Galeras Bárbara D'Achille National Reserve in Peru

Hemotrophic mycoplasmas (hemoplasmas) are epierythrocytic bacteria that infect wild and domestic animals, and can cause anemia in some of them. They are considered emerging and zoonotic pathogens, causing serious health problems in wildlife. Candidatus Mycoplasma haemolamae is the only species of hemoplasma that infects domestic South American camelids (alpacas and llamas), with limited studies in wild camelids. Therefore, the objective of this study was to determine the prevalence of Candidatus M. haemolamae in vicunas (Vicugna vicugna) from the Pampa Galeras National Reserve, located in the Ayacucho region of Peru, using molecular diagnosis. For this, blood samples from 79 vicunas were collected, which were molecularly analyzed by partially amplifying the 16S ribosomal RNA gene of Mycoplasma sp. Fourteen vicunas (17.7 %) were positive for the molecular diagnosis of Mycoplasma sp. All PCR-positive products were sequenced and showed more than 99 % identity with Candidatus M. haemolamae. Statistical analysis showed that tick-infested vicunas had 6.10 odds of presenting Candidatus M. haemolamae compared with tick-free vicunas. Sex and age were not associated with Candidatus M. haemolamae infections. This is the first report of hemoplasmas in vicunas, a wild South American camelid, demonstrating that the pathogen can have both a domestic and a wild life cycle. Future studies are necessary to know the current situation of this pathogen in domestic and wild camelids from other locations in Peru.

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.

Occurrence of 'Candidatus Mycoplasma haemosuis' in fattening pigs, sows and piglets in Germany using a novel gap-based quantitative real-time PCR assay

Background

The appearance of the novel porcine haemotrophic mycoplasma (HM) species ‘Candidatus Mycoplasma haemosuis’ was reported in apparently healthy but also in clinically sick animals in China, Korea and in a case report from Germany. Outside of Asia, however, nothing further is known about the frequency of ‘Ca. M. haemosuis’ in pigs to date. To investigate the distribution of this novel HM species in Germany, fattening pigs, sows and pre-suckling piglets were examined using a herein developed quantitative real-time PCR assay (qPCR). Because the piglets were sampled before the first colostrum uptake, additional information on a possible vertical transmission from dams to their offspring was obtained.

Results

Our novel qPCR assay successfully detected ‘Ca. M. haemosuis’ in all blood samples from the ‘Ca. M. haemosuis’-infected pigs. No cross-reactivity was detected when DNA from non-target Mycoplasma spp. and other bacterial species representing 10⁵ bacteria/reaction were used as a template. The lower limit of detection of the qPCR was thus 10 gap gene copies per reaction and 2.5 x 10³ genome equivalents (GE) per mL blood.

‘Candidatus M. haemosuis’ was detected by this qPCR in blood samples from a total out of 6.25% sows (13/208), 4.50% pre-suckling piglets (28/622) and 17.50% fattening pigs (35/200). On farm level, 3 out of 21 piglet producing farms (14.28%) and 9 out of 20 fattening farms (45.00%) were positive for ‘Ca. M. haemosuis’. Co-infections with M. suis were evident in all age groups.

Conclusion

‘Candidatus M. haemosuis’ infection is present in German pig farms and the detection of the novel porcine HM species in piglets immediately after birth before colostrum intake indicates vertical transmission. The novel qPCR assay specific for ‘Ca. M. haemosuis’ described herein will be a prerequisite for future studies on the prevalence, epidemiology as well as the clinical and economic impact of ‘Ca. M. haemosuis’ infections.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03147-1.

Molecular survey and genetic characterization of 'Candidatus Mycoplasma haemolamae' in llamas (Lama glama) and alpacas (Vicugna pacos) from Southern Chile

This study aimed to perform a molecular survey and identification of hemotropic Mycoplasma spp. in domestic South American Camelids from Southern Chile. Conventional PCR (cPCR) for hemotropic Mycoplasma spp. based on 16S rRNA gene (620bp fragment) was performed in 87 EDTA-blood samples taken from 48 llamas (Lama glama) and 39 and alpacas (Vicugna pacos) from to Temuco, La Araucanía region and Valdivia, Los Rios region, Southern Chile. 16S rRNA hemotropic Mycoplasma PCR-positive were sequenced for species identification, phylogenetic and haplotype analyses, and further tested by cPCR targeting a fragment (160-210 bp) of the RNaseP (rnpB) gene. Based upon 16S rRNA cPCR results, the overall hemotropic Mycoplasma spp. occurrence in Southern camelids was 9.2% (8/87 [95% CI (4.0-17.3%)]), with five positive alpacas (12.8%; 5/39 [95% CI (4.3-27.4%)]) and three llamas (6.3%; 3/48 [95% CI (1.7-17.2%)]). All 16S rRNA PCR-positive samples were negative for the rnpB gene. Obtained 16S sequences presented high identity (99-100%) by BLASTn analysis to 'Candidatus Mycoplasma haemolamae' from an alpaca in the United Kingdom. Phylogenetic and haplotype analyses of the 16s rRNA gene showed high similarity among 'Candidatus M. haemolamae' sequences of this study and the ones from North America, Europe, and Asia evidencing a low diversity of Chilean samples, with only one haplotype detected (#1). Haplotype #1 from South American Camelids in Chile was worldwide distributed and observed in North America, Europe, and Asia. 'Candidatus M. haemolamae' detected for the first time in South American camelids in Southern Chile had low diversity and was worldwide spread.

Mycoplasma haemolamae and intestinal parasite relationships with erythrocyte variables in clinically healthy alpacas and llamas

Background

Mycoplasma haemolamae (Mhl) and gastrointestinal nematodes can cause anemia in camelids. Control programs aim to suppress parasitism without promoting anthelminthic resistance, but few evidence‐based guidelines define acceptable parasite loads in camelids.

Hypothesis/Objectives

In clinically healthy nonanemic camelids, compare erythrocyte variables to Mhl real‐time PCR status and to fecal egg count (FEC). Determine the FEC threshold above which erythrocyte variables are consistently below reference interval medians.

Animals

One hundred fourteen client‐owned adult alpacas and llamas.

Methods

In a cross‐sectional study, whole blood in ethylenediaminetetraacetic acid (EDTA) was assessed for packed cell volume (PCV) by centrifugation, erythrocyte count (RBC), and hemoglobin concentration (HGB) using an ADVIA120 analyzer, and Mhl using real‐time PCR. Trichostrongyle eggs per gram (epg) were counted by modified McMaster test on freshly collected feces. Significant differences in erythrocyte variables based on Mhl status and FEC thresholds were assessed by independent t test and one‐way ANOVA, respectively.

Results

Packed cell volume, RBC, and HGB were not significantly different between Mhl‐positive and Mhl‐negative animals, but were significantly lower in animals with FEC >1000 epg compared to those with <500 epg. All animals with FEC >600 epg had RBC and HGB below the reference interval median. All animals with FEC >750 epg had PCV below the reference interval median.

Conclusions and Clinical Importance

In healthy nonanemic camelids, positive Mhl PCR is not associated with lower erythrocyte variables and such animals may not warrant treatment. Fecal egg count >600‐750 epg has a negative effect on erythrocyte variables, and may be a guide for deworming protocols.

Prevalence of Candidatus Mycoplasma haemolamae, bovine viral diarrhoea virus, and gastrointestinal parasitism in a sample of adult New Zealand alpaca (Vicugna pacos)

AIM

To determine the prevalence of infection with Candidatus Mycoplasma haemolamae (Mhl), antibodies to bovine viral diarrhoea virus (BVDV), and BVDV antigen, and the prevalence of animals with elevated faecal nematode egg counts (FEC) in a sample of adult New Zealand alpaca (Vicugna pacos).

METHODS

Blood samples were obtained from 175 alpaca, collected from 15 farms around New Zealand, and from 31 samples sent to a diagnostic laboratory for routine haematology. Blood smears (n=170) were examined microscopically for the presence of haemoplasma, and DNA was extracted from whole blood (n=206) for real-time PCR testing for Mhl. Packed cell volume (PCV) was determined for 193 samples. Serum samples (n=195) were tested for BVDV antibody using ELISA, and for BVDV antigen using a real-time PCR assay. Faecal samples were collected from 143 animals; FEC were measured, and samples pooled for larval culture.

RESULTS

No haemoplasma organisms were present on blood smear examination. Of the 206 blood samples, two (from the same farm) were positive for Mhl by real-time PCR testing, giving a prevalence of infection with Mhl of 0.97%. Of the 195 serum samples tested, four (2.1%) were positive for antibodies to BVDV; animals with BVDV antibodies were from 3/15 (20%) farms, none of which farmed cattle. None of the serum samples were positive by PCR for BVDV antigen. The median FEC was 50 epg (min 0, max 4,700), with 55/143 (38.5%) samples having 0 epg, and 33/143 (23.1%) having ≥250 epg. Haemonchus spp. were the most common nematodes present in faecal larval cultures from the North Island. Log₁₀ FEC was negatively associated with PCV (p=0.02), and was higher in males than females (p<0.001), and in animals that were positive compared with negative for Mhl (p=0.022).

CONCLUSIONS AND CLINICAL RELEVANCE

The number of alpaca infected with Mhl was low, as was the seroprevalence of BVDV. Gastrointestinal parasitism was, however, a common finding in this sample of New Zealand alpaca.

Detection of hemoplasma infection of goats by use of a quantitative polymerase chain reaction assay and risk factor analysis for infection

OBJECTIVE To develop and validate a real-time quantitative PCR (qPCR) assay for the detection and quantification of Mycoplasma ovis in goats and investigate the prevalence and risk factors for hemoplasma infection of goats located in Indiana. ANIMALS 362 adult female goats on 61 farms. PROCEDURES Primers were designed for amplification of a fragment of the dnaK gene of M ovis by use of a qPCR assay. Blood samples were collected into EDTA-containing tubes for use in total DNA extraction, blood film evaluation, and determination of PCV. Limit of detection, intra-assay variability, interassay variability, and specificity of the assay were determined. RESULTS Reaction efficiency of the qPCR assay was 94.45% (R(2), 0.99; slope, -3.4623), and the assay consistently detected as few as 10 copies of plasmid/reaction. Prevalence of infection in goats on the basis of results for the qPCR assay was 18.0% (95% confidence interval, 14% to 22%), with infected goats ranging from 1 to 14 years old, whereby 61% (95% confidence interval, 47% to 73%) of the farms had at least 1 infected goat. Bacterial load in goats infected with M ovis ranged from 1.05 × 10(3) target copies/mL of blood to 1.85 × 10(5) target copies/mL of blood; however, no bacteria were observed on blood films. Production use of a goat was the only risk factor significantly associated with hemoplasma infection. CONCLUSIONS AND CLINICAL RELEVANCE The qPCR assay was more sensitive for detecting hemoplasma infection than was evaluation of a blood film, and production use of a goat was a risk factor for infection.

Prevalence and risk factor analysis of feline haemoplasma infection in New Zealand domestic cats using a real-time PCR assay

Haemotropic mycoplasmas (haemoplasmas) are small epierythrocytic bacteria that have the potential to cause severe, life-threatening haemolytic anaemia. The aim of the current study was to evaluate feline haemoplasma prevalence using real-time polymerase chain reaction (PCR) from a convenience sample of New Zealand domestic cats, including blood film examination and a risk factor analysis. DNA was extracted from 200 blood samples submitted to a diagnostic laboratory for routine haematology over a 12-month period. Species-specific real-time PCR assays identified 62 cats that were positive for haemoplasma DNA, giving an overall prevalence of 31%. Twelve of the positive cats had dual infections. The prevalence of the three feline haemoplasmas was 25% for 'Candidatus Mycoplasma haemominutum', 7.5% for Mycoplasma haemofelis and 4.5% for 'Candidatus Mycoplasma turicensis' (CMt). All samples were positive for an internal control (feline 28S rDNA) by real-time PCR. Sensitivity and specificity of blood smear examination for haemoplasma infection in this study was 9.7% and 97.8%, respectively. Retroviral infection was tested using the Idexx Snap Feline Triple test on all samples. Twenty cats (10%) were feline immunodeficiency virus (FIV) positive and 11 cats (5.5%) were feline leukaemia virus (FeLV) positive. Statistical comparisons, using multivariate logistic regression, indicated that positive FIV status, male gender and non-pedigree breed were significantly (P <0.05) associated with haemoplasma infection, with odds ratios of 10.16, 5.04 and 3.03, respectively. The results of this study demonstrate the prevalence of the three main feline haemoplasma species in New Zealand for the first time, with prevalences correlating with previous overseas studies. This is the first report of CMt in New Zealand.

Genome sequence of "Candidatus Mycoplasma haemolamae" strain purdue, a red blood cell pathogen of alpacas (Vicugna pacos) and llamas (Lama glama)

We report the complete genome sequence of "Candidatus Mycoplasma haemolamae," an endemic red-cell pathogen of camelids. The single, circular chromosome has 756,845 bp, a 39.3% G+C content, and 925 coding sequences (CDSs). A great proportion (49.1%) of these CDSs are organized into paralogous gene families, which can now be further explored with regard to antigenic variation.