CYTAUXZOON FELIS DNA DETECTION IN HEALTHY CATS FROM RIO DE JANEIRO, BRAZIL

Molecular detection of vector-borne pathogens in cats tested for FIV and FeLV

The aim of this study was to detect molecularly vector borne pathogens (VBPs) in domiciled cats tested for Feline immunodeficiency virus (FIV) and Feline leukemia virus (FeLV). Blood samples (n = 119) were analyzed microscopically and molecularly through PCR and sequenced for the detection of the following pathogens: piroplasmids., Bartonella henselae, Cytauxzoon felis, Ehrlichia canis, Leishmania spp., hemotropic Mycoplasma spp., Trypanosoma spp., and Ricketssia spp. Animals were also serological assessed for detection of antibodies against FIV and FeLV. Out of all animals, 20.16% (24/119) tested positive for at least one VBPs at molecular examination. Conversely, no animal resulted positive at microscopic analysis. The most prevalent pathogen was hemotropic Mycoplasma haemofelis (8.40%; 10/119), followed by Candidatus Mycoplasma haemominutum (5.88%; 7/119), E. canis (5.04%; 6/119), C. felis (0.84%; 1/119) and B. henselae (0.84%; 1/119). One animal (0.84%; 1/119) was co-infected with. E. canis and B. henselae. A total of 5.88% (7/119) and 1.68% (2/119) tested positive for FIV and FeLV, respectively. Data of this study demonstrate that owned cats can be at risk of hemotropic Mycoplasma spp., E. canis, C. felis and B. henselae. Therefore, preventive measures against vectors of these pathogens should be implemented in order to reduce the risk of exposition and consequently infection. Additionally, aggressive behaviors among cats should be avoided, especially because hemotropic Mycoplasma spp. may be transmitted through the bite of animals.

A Novel Vaccine Strategy to Prevent Cytauxzoonosis in Domestic Cats

Cytauxzoonosis is caused by Cytauxzoon felis (C. felis), a tick-borne parasite that causes severe disease in domestic cats in the United States. Currently, there is no vaccine to prevent this fatal disease, as traditional vaccine development strategies have been limited by the inability to culture this parasite in vitro. Here, we used a replication-defective human adenoviral vector (AdHu5) to deliver C. felis-specific immunogenic antigens and induce a cell-mediated and humoral immune response in cats. Cats (n = 6 per group) received either the vaccine or placebo in two doses, 4 weeks apart, followed by experimental challenge with C. felis at 5 weeks post-second dose. While the vaccine induced significant cell-mediated and humoral immune responses in immunized cats, it did not ultimately prevent infection with C. felis. However, immunization significantly delayed the onset of clinical signs and reduced febrility during C. felis infection. This AdHu5 vaccine platform shows promising results as a vaccination strategy against cytauxzoonosis.

Piroplasmid infection is not associated with clinicopathological and laboratory abnormalities in cats from Midwestern Brazil

Feline piroplasmids include the genera Babesia spp., Cytauxzoon spp., and Theileria spp. In Brazil, there are few reports regarding these hemoprotozoans; however, clinicopathological and molecular data are scarce. This study aimed to characterize the clinical relevance of these parasites through hematological, biochemical, and molecular approaches. For this purpose, 166 cats from Brasilia, Federal District, Midwestern Brazil, were screened using a quantitative polymerase chain reaction (qPCR) for piroplasmids based on the LSU4 mitochondrial gene, which resulted in an overall prevalence of 36/166 (21.7%). Twelve of 166 samples (7.2%) were positive for C. felis, while 19/166 (11.4%) were positive for Babesia vogeli. No samples tested positive for Theileria spp. Babesia vogeli and Cytauxzoon spp. LSU4 sequences showed identities of 97-100% and 99.3%, respectively, to US isolates. The hematological and biochemical findings did not differ significantly between the cats that tested positive and negative for piroplasmids. Although the lack of abnormalities in clinical and laboratory parameters does not eliminate the possibility that these cats were sick and recovered, it may suggest that the Brazilian strain of Cytauxzoon spp. is not as pathogenic as that from the USA, despite the high molecular identity with North American isolates.

Molecular Detection of Tick-Borne Agents in Cats from Southeastern and Northern Brazil

Even though the epidemiology of tick-borne agents (TBA) in dogs has been extensively investigated around the world, the occurrence, vectors involved, and molecular identity of these agents in cats remains elusive in many regions. Among TBA, Ehrlichia, Anaplasma, Babesia, Cytauxzoon, and Hepatozoon are responsible for diseases with non-specific clinical signs in cats, making essential the use of molecular techniques for accurate diagnosis and proper treatment. The present work aimed to investigate the occurrence and molecular identity of tick-borne agents (Ehrlichia, Anaplasma, Babesia/Theileria, Cytauxzoon, and Hepatozoon) in cats from southeastern (states of São Paulo (SP) and Minas Gerais (MG)) and northern (state of Rondônia (RO)) Brazil. For this purpose, 390 blood samples were collected from domiciled cats in MG (n = 155), SP (n = 151), and RO(n = 84) states, submitted to DNA extraction and PCR assays for Ehrlichia spp. (dsb gene), Anaplasma spp. (rrs gene), piroplasmids (18S rRNA gene), and Hepatozoon spp. (18S rRNA gene), sequencing, and phylogenetic inferences. The overall positivity for Anaplasma spp., Ehrlichia spp., Babesia/Theileria spp., Cytauxzoon spp., and Hepatozoon spp. were 7.4% (12.3% (MG) and 6.6% (SP)), 2% (4.5% (MG) and 0.6% (SP)), 0.7% (0.6% (MG), 0.6% (SP) and 1.2% (RO)), 27.2% (41.9% (MG), 24.5% (SP) and 4.8% (RO), and 0%, respectively. The phylogenetic analysis grouped the obtained sequences with 'Candidatus Anaplasma amazonensis', A. platys, B. vogeli, and Cytauxzoon sp. previously detected in wild felids from Brazil. qPCR specific for E. canis based on the dsb gene confirmed the molecular identity of the detected ehrlichial agent. The present study expanded the list and geographical distribution of hemoparasites in cats. 'Candidatus Anaplasma amazonensis', recently detected in sloths from northern Brazil, was described for the first time in cats. This is the first report of piroplasmids infecting cats in northern Brazil. Coinfection by Cytauxzoon and other TBA (Ehrlichia, Anaplasma, and B. vogeli) reported in the present study raises the need for veterinary practitioners' awareness of cats parasitized by multiple TBA.

Fatal infection caused by Cytauxzoon felis in a captive-reared jaguar (Panthera onca)

Fatal infections with Cytauxzoon felis are common in domestic cats, and jaguars (Panthera onca) are believed carriers of this protozoan. Fatal C. felis infections have never been described in jaguars before. Thus, this study describes such an infection in a 5-month-old captive-reared jaguar that presented hyporexia and died at 26 days after the first clinical signs. During necropsy, samples were taken from several tissues, some were fixed in 10% formalin and process for histopathological diagnosis, and some samples were used for DNA extraction, amplification via PCR and sequencing of the potential pathogens. Grossly, marked splenomegaly and icterus were observed. Histologically, numerous structures that are morphologically compatible with Cytauxzoon spp. schizonts obliterated multiple blood vessels in the brain, leptomeninges, spinal cord, lungs, heart, skeletal muscle, adrenal gland, kidneys, spleen, small intestine and pancreas. C. felis was identified by PCR in many organs. Thus, C. felis infection in jaguars can be fatal, and the clinicopathological findings are similar to those of cytauxzoonosis in other wild and domestic felid species.