Molecular detection of Mycoplasma haemofelis and 'Candidatus Mycoplasma haemominutum' Infection in cats by direct PCR using whole blood without DNA extraction

Molecular Investigation and Characterization of Mycoplasma spp. infections in Naturally Infected Cats in Thailand

PURPOSE

Mycoplasma spp. are hemotropic parasites that attach to the surface of red blood cells, causing hemolytic anemia in infected cats. These pathogens can result in significant clinical consequences, including death if left untreated. Despite their importance, molecular studies on Mycoplasma infections in Thailand remain limited. This study aimed to determine the prevalence of Mycoplasma spp. infections in cats, identify specific species involved, and assess hematologic changes in infected cats. Additionally, phylogenetic relationships of Mycoplasma species were analyzed.

METHODS

A total of 149 blood samples were collected from cats visiting veterinary hospitals in four provinces of Thailand including Samut Prakan, Udon Thani, Chaiyaphum, and Maha Sarakham for routine check-ups, vaccinations, or illness, without specific signs of infection. PCR targeting the 16S rRNA gene was used to detect Mycoplasma spp., followed by DNA sequencing and phylogenetic analysis for species identification.

RESULTS

The overall prevalence of Mycoplasma spp. infection was 17.45% (95% CI: 11.73-24.51), comprising Candidatus Mycoplasma haemominutum (CMhm) (14.09%), Mycoplasma haemofelis (Mhf) (2.01%), and Candidatus Mycoplasma turicensis (CMt) (1.34%). Sequencing of 26 positive PCR products identified CMhm in 21 samples, Mhf in 3 samples, and CMt in 2 samples, revealing seven distinct haplotypes. All Mycoplasma species identified in this study showed 99-100% nucleotide similarity with those available in the GenBank database. Hematologic analysis revealed no significant changes in most parameters, except for a statistically significant decrease in platelet count (P < 0.01).

CONCLUSIONS

This study provides information on the molecular epidemiology and genetic identification of Mycoplasma spp., contributing to a better understanding of hemoplasma infections in Thai cats, which will aid in the control of these microorganisms.

Evidence of SARS-CoV-2 infection and co-infections in stray cats in Brazil

The zoonotic virus SARS-CoV-2, which causes severe acute respiratory syndrome in humans (COVID-19), has been identified in cats. Notably, most positive cases were in cats that had close contact with infected humans, suggesting a role for humans in animal transmission routes. Previous studies have suggested that animals with immune depletion are more susceptible to SARS-CoV-2 infection. To date, there is limited evidence of SARS-CoV-2 infections in stray and free-range cats affected by other pathogens. In this study, we investigated infections caused by SARS-CoV-2, Leishmania spp., Toxoplasma gondii, Mycoplasma spp., Bartonella spp., Feline leukemia virus (FeLV), and Feline immunodeficiency virus (FIV) in stray cats from an urban park in Brazil during the COVID-19 pandemic. From February to September 2021, 78 mixed-breed cats were tested for SARS-CoV-2 and hemopathogens using molecular analysis at Américo Renné Giannetti Municipal Park, Belo Horizonte, Minas Gerais, Brazil. An enzyme-linked immunosorbent assay (ELISA) was used to detect IgG in T. gondii. None of the animals in this study showed any clinical signs of infections. The SARS-CoV-2 virus RNA was detected in 7.7 % of cats, and a whole virus genome sequence analysis revealed the SARS-CoV-2 Delta lineage (B.1.617.2). Phylogenetic analysis showed that SARS-CoV-2 isolated from cats was grouped into the sublineage AY.99.2, which matches the epidemiological scenario of COVID-19 in the urban area of our study. Leishmania infantum was detected and sequenced in 9 % of cats. The seroprevalence of T. gondii was 23.1 %. Hemotropic Mycoplasma spp. was detected in 7.7 % of the cats, with Mycoplasma haemofelis and Candidatus Mycoplasma haemominutum being the most common. Bartonella henselae and Bartonella clarridgeiae were detected in 38.5 % of the cats, FeLV was detected in 17,9 %, and none of the cats studied tested positive for FIV. This study reports, for the first time, the SARS-CoV-2 infection with whole-genome sequencing in stray cats in southeastern Brazil and co-infection with other pathogens, including Bartonella spp. and Feline leukemia virus. Our study observed no correlation between SARS-CoV-2 and the other detected pathogens. Our results emphasize the importance of monitoring SARS-CoV-2 in stray cats to characterize their epidemiological role in SARS-CoV-2 infection and reinforce the importance of zoonotic disease surveillance.

Co-infection patterns of vector-borne zoonotic pathogens in owned free-ranging dogs in central Chile

We investigated the co-occurrence of the nine of the most relevant canine vector-borne pathogens (CVBP) using conventional and real-time PCR and evaluated risk factors and potential non-apparent haematological alterations associated with co-infection in 111 rural, owned, free-ranging dogs in the Metropolitan Region of Chile.

At least one pathogen was detected in 75% of the dogs. DNA of Anaplasma platys (Ap; 36%), Candidatus Mycoplasma haematoparvum (CMhp; 31%), Mycoplasma haemocanis (Mhc; 28%), Trypanosoma cruzi (17%), Leishmania spp. (4.5%), and Acanthocheilonema reconditum (1%) was detected. All dogs were negative for Ehrlichia spp., Rickettsia spp., Bartonella spp., Piroplasmida, and Hepatozoon spp. Thirty-eight dogs (34%) were coinfected. CMhp was involved in 71%, Mhc in 58%, and Ap in 50% of the co-infections. The most common co-infection pattern was CMhp–Mhc (37% of the cases). The prevalence of Ap was higher in juvenile than in adult dogs, whereas the opposite was found for CMhp and Mhc. Adult dogs were four times more likely of being co-infected than juveniles. Co-infected animals showed higher white blood cell count, segmented neutrophil count, and GGT levels than non-co-infected dogs. Clinically healthy but infected dogs may act as reservoirs of CVBP, and their free-ranging behavior would facilitate the spread of these pathogens to other dogs as well as human beings or wild carnivores.

Implications of Mycoplasma haemofelis bacterial load on the haematological parameters of naturally infected cats

Mycoplasma haemofelis is the most pathogenic haemoplasma species that affect cats. M. haemofelis may cause an acute infection that leads to haemolytic anaemia. The objective of this study was to detect and to quantify the load of M. haemofelis in cats by conventional polymerase chain reaction (PCR) and by quantitative PCR (qPCR) and to describe the possible haematological changes. M. haemofelis DNA was detected in 28.6% of the randomly selected cats (42 of 147) attended at the Veterinary Hospital of the Federal University of Mato Grosso, Brazil. The agreement between conventional PCR and qPCR was substantive (k 0.6). Females were twice as likely to acquire infection as males (odds ratio, 2.31). There was no statistically significant association (p > 0.05) and little/no correlation between the haematological parameters and the average of bacterial load. The results indicate that M. haemofelis infection is not related to clinical signs and bacterial blood load in cats. The agreement between conventional and quantitative PCR made it possible to detect infection by M. haemofelis in a larger number of cats.

Assessing cross-species transmission of hemoplasmas at the wild-domestic felid interface in Chile using genetic and landscape variables analysis

The co-occurrence of domestic cats (Felis silvestris catus) and wild felids in rural landscapes can facilitate pathogen transmission. However, in the relatively-isolated regions of southern South America there have been no comprehensive studies to assess disease transmission risks between domestic cats and forest-dwelling wild felids such as guigna (Leopardus guigna). We evaluated hemoplasma infection and the possibility of transmission between domestic cats and guignas by comparing spatial and phylogenetic patterns of pathogen prevalence. Blood/spleen samples were collected from 102 wild guignas and 262 co-occurring rural domestic cats across the entire distribution range of guigna in Chile. Hemoplasma infection was assessed by direct sequencing of the 16S RNA gene. Infection with hemoplasmas was common and geographically widespread across different bioclimatic areas for both species. The most common feline Mycoplasma species in guigna and domestic cats were Candidatus M. haemominutum (CMhm) (15.7% guigna; 10.3% domestic cat) and Mycoplasma haemofelis (Mhf) (9.8% guigna, 6.1% domestic cat). A previously undescribed Mycoplasma sp. sequence was found in two guignas and one cat. Continuous forest-landscapes were associated with higher hemoplasma-prevalence in guignas. Shared hemoplasma nucleotide sequence types between guigna and domestic cats were rare, suggesting that cross-species transmission between guignas and domestic cats may occur, but is probably uncommon. Ectoparasites, which have been linked with hemoplasma transmission, were not found on guignas and were infrequent on domestic cats. Our results suggest that transmission pathways vary among hemoplasma species and, contrary to our predictions, domestic cats did not appear to be the main driver of hemoplasma infection in guignas in these human-dominated landscapes.

Direct polymerase chain reaction from blood and tissue samples for rapid diagnosis of bovine leukemia virus infection

Bovine leukemia virus (BLV) infection induces bovine leukemia in cattle and causes significant financial harm to farmers and farm management. There is no effective therapy or vaccine; thus, the diagnosis and elimination of BLV-infected cattle are the most effective method to eradicate the infection. Clinical veterinarians need a simpler and more rapid method of diagnosing infection, because both nested polymerase chain reaction (PCR) and real-time PCR are labor intensive, time-consuming, and require specialized molecular biology techniques and expensive equipment. In this study, we describe a novel PCR method for amplifying the BLV provirus from whole blood, thus eliminating the need for DNA extraction. Although the sensitivity of PCR directly from whole blood (PCR-DB) samples as measured in bovine blood containing BLV-infected cell lines was lower than that of nested PCR, the PCR-DB technique showed high specificity and reproducibility. Among 225 clinical samples, 49 samples were positive by nested PCR, and 37 samples were positive by PCR-DB. There were no false positive samples; thus, PCR-DB sensitivity and specificity were 75.51% and 100%, respectively. However, the provirus loads of the samples detected by nested PCR and not PCR-DB were quite low. Moreover, PCR-DB also stably amplified the BLV provirus from tumor tissue samples. PCR-DB method exhibited good reproducibility and excellent specificity and is suitable for screening of thousands of cattle, thus serving as a viable alternative to nested PCR and real-time PCR.

Prevalence and risk factor analysis of bovine hemoplasma infection by direct PCR in Eastern Hokkaido, Japan

The prevalence and risk factors of 2 bovine hemoplasma species-Mycoplasma wenyonii (Mw) and "Candidatus Mycoplasma haemobos" (CMh)-were examined by direct PCR using whole blood samples collected from 343 cattle in Eastern Hokkaido, Japan. The sensitivity of the direct PCR assay was 10-fold higher than the standard PCR assay, detecting 5 copies of bovine hemoplasma DNA per reaction. An epidemiological survey of sampling location, living conditions, age and bovine leukemia virus antibody was performed to assess infection risk factors. The prevalence rates were 38.5% for Mw and 39.1% for CMh, respectively, with an overall prevalence rate of 64.7% for all bovine hemoplasma infections. Significant differences were found in sampling location, living conditions and age. Compared with pastured cattle, farmed cattle were significantly more susceptible to infection with total hemoplasma species (P<0.001), and were particularly susceptible to CMh (P<0.001). Cattle that were 1-3 years of age were more susceptible to infection with hemoplasma compared with other age groups. Bovine leukemia virus infection status was not significantly associated with hemoplasma infections. Blood examination revealed significantly lower RBC, Hb, and PCV levels, and a higher MCV in infected cattle than in noninfected cattle.

A feline hemoplasma, 'Candidatus Mycoplasma haemominutum', detected in dog in Japan

We examined for 'Candidatus Mycoplasma haemominutum' infection in 167 blood samples collected from domestic dogs between 2008 and 2009 in the Tohoku area, Japan, and found 5 (3.0%) were positive by PCR assay. This is the first demonstration of 'Candidatus Mycoplasma haemominutum', a feline haemotropic mycoplasma, in the dogs raised in Japan.

An epidemiological survey of feline hemoplasma infection in Japan

Hemoplasma (hemotropic mycoplasma) often causes hemolytic anemia in infected cats, especially those with immune suppression. An updated nationwide epidemiological survey of feline hemoplasmosis was conducted in Japan. Blood samples were collected from 1,770 outdoor-accessing cats from March to October 2008. The infections were molecularly detected by PCR analyses, which are able to distinguish Mycoplasma haemofelis (Mhf), `Candidatus M. haemominutum' (CMhm), and `Candidatus M. turicensis' (CMt) infections. Of the 1,770 cats, 468 cases (26.4%) revealed a single- or co-infection of feline hemoplasmas [Mhf alone, 42 cases (2.4%); CMhm alone, 280 cases (15.8%); CMt alone, 48 cases (2.7%); Mhf+CMhm, 28 cases (1.6%); Mhf+CMt, 6 cases (0.3%); CMhm+CMt, 50 cases (2.8%); Mhf+CMhm+CMt, 14 cases (0.8%)]. In addition, male gender, middle to old age, history of fight wounds, and feline immunodeficiency virus infection were shown to be risk factors for hemoplasma infection. Close attention must be paid to the acute onset of disease in feline practice because a prevalence of hemoplasma infection was detected even in clinically healthy cats.