Molecular Detection of Gurltia paralysans by Semi-Nested PCR in Cerebrospinal Fluid and Serum Samples from Domestic Cats (Felis catus)

SIMPLE SUMMARY: Feline gurltiosis is a parasitic myelopathy caused by Gurltia paralysans. This nematode infects domestic cats without distinction of sex, breed or age, invading the venous system of the spinal leptomeninges and causing vascular congestion that mainly produces paralysis of the pelvic limbs, among other clinical signs of chronic myelopathy. To date, the definitive diagnosis of feline gurltiosis is only possible through post-mortem analysis that shows the location of the parasite in the vasculature of the spinal cord. For this reason, this investigation aimed to detect G. paralysans DNA, via semi-nested PCR, in samples of cerebrospinal fluid and serum from 12 domestic cats from potentially endemic areas in southern Chile, with compatible signs of feline gurltiosis. The presence of G. paralysans-specific DNA was detected in the cerebrospinal fluid of four out of nine cats and the sera of seven out of seven cats. These results allow us to suggest the implementation of a semi-nested PCR technique as a routine diagnostic test for early and timely detection of feline gurltiosis. ABSTRACT: Gurltia paralysans is an angio-neurotropic metastrongyloid nematode that infects domestic and wild cats, invading the veins of the subarachnoid space of the spinal cord and mainly causing progressive paralysis of the pelvic limbs. The definitive diagnosis of feline gurltiosis can only be achieved by post-mortem examination that reveals the presence of the nematode in the spinal cord vein vasculature. An early diagnosis with conclusive results is required since laboratory and imaging findings are not sufficient. Therefore, the purpose of this study was to detect the presence of G. paralysans, via semi-nested PCR, in samples of cerebrospinal fluid (CSF) and the sera of domestic cats naturally infected with the parasite. A total of 12 cats with a diagnosis suggestive of feline gurltiosis were selected, and they underwent a complete neurological and imaging examination. DNA samples were analysed by semi-nested PCR, with universal (AaGp28Sa1/AaGp28Ss1) and specific (Gp28Sa3/Aa28Ss2) primers, for G. paralysans (G. paralysans 18S rRNA gene, partial sequence; ITS 1, 5.8S rRNA gene, and ITS 2, complete sequence; and 28S rRNA gene, partial sequence) and Aelurostrongylus abstrusus, obtaining amplifications of 356 and 300 bp, which indicated the presence or absence of nematode DNA, respectively. The presence of G. paralysans was detected in the CSF of four out of nine cats, and the sera of seven out of seven cats. In the sera analysis of five out of seven cats, a mixed infection with A. abstrusus was found, despite no alterations of the respiratory tract being observed during the necropsies. It is proposed that serum samples could be more effective than CSF in detecting the parasite by PCR analysis. Sequencing analysis showed high percentages of identity with G. paralysans, which indicated the feasibility of detection and the sensitivity/specificity of the method used, suggesting the implementation of semi-nested PCR as a routine diagnostic test for early and timely detection of feline gurltiosis.