Molecular Detection of Feline Leukemia Virus in Oral, Conjunctival, and Rectal Mucosae Provides Results Comparable to Detection in Blood

Feline leishmaniasis in an animal shelter in northeastern Brazil: Clinical aspects, coinfections, molecular detection, and serological study of a new recombinant protein

Infection and clinical cases of leishmaniasis caused by Leishmania infantum in cats have been increasingly reported in several countries, including Brazil. In this study, we used an enzyme-linked immunosorbent assay (ELISA) and an immunochromatographic test (ICT) based on a recombinant antigen (rKDDR-plus) to detect anti-Leishmania antibodies in cats from an animal shelter in northeastern Brazil. We compared the results with an ELISA using L. infantum crude antigen (ELISA-CA). We also investigated the presence of Leishmania DNA in blood or ocular conjunctival samples as well as the association between Leishmania PCR positivity and serological positivity to feline immunodeficiency virus (FIV), feline leukemia virus (FeLV) and Toxoplasma gondii. Concerning serological assays, a higher positivity was detected using the ICT-rKDDR-plus (7.5%; 7/93) as compared to ELISA-rKDDR-plus (5.4%; 5/93) and ELISA-CA (4.3%; 4/93). Upon PCR testing, 52.7% (49/93) of the ocular conjunctival swabs and 48.3% (44/91) of the blood samples were positive. Together, PCR and serological testing revealed overall positivities of 73.1% (68/93) and 12.9% (12/93), respectively. Among PCR-positive samples, 45.5% (31/68) showed co-infection with FIV, 17.6% (12/68) with FeLV, and 82.3% (56/68) with T. gondii. More than half of the PCR-positive cats showed at least one clinical sign suggestive of leishmaniasis (58.8%; 40/68) and dermatological signs were the most frequent ones (45.5%; 31/68). Both tests employing the recombinant antigen rKDDR-plus (i.e., ICT-rKDDR-plus and ELISA-rKDDR-plus) detected more positive cats than the ELISA-CA but presented low overall accuracy. PCR testing using either blood or ocular conjunctival samples detected much more positive cats than serological tests.

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.

Detection and molecular characterisation of feline viruses from swab samples

Feline calicivirus (FCV), feline alphaherpesvirus 1 (FHV-1) and feline panleukopenia virus (FPLV) as well as retroviral agents such as feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV) are important viral pathogens of cats. The aim of this study was to detect and characterise FHV-1, FPLV, FeLV, FIV and feline foamy virus (FFV) in oropharyngeal, nasal and conjunctival swabs from 93 cats that had been screened for FCV previously. We wanted to determine the possible risk factors for infection with these viruses. The prevalence was found to be 12.9% for FHV-1 and 9.7% for FPLV. FIV was detected only in two samples and FeLV in one sample, whereas the presence of FFV was not demonstrated in any of the clinical samples. The statistical analysis of the results showed that breed, age, health status, and lifestyle are important predisposing factors to FHV-1 (P < 0.05). For FPLV, only clinically unhealthy animals were found to be at risk (P < 0.001). Sequence analysis revealed that the two FIV-positive samples in this study contained different (A and B) subtypes of the virus. This is the first report on the occurrence of subtype A FIV in Turkey.