Naegleria fowleri glycoconjugates with residues of α-d-mannose are involved in adherence of trophozoites to mouse nasal mucosa

Abstract

We analyzed the possible role of glycoconjugates containing α-D-mannose and α-D-glucose residues in adherence of trophozoites to mouse nasal epithelium. Trophozoites incubated with 20 μg of one of three different lectins which preferentially recognized these residues were inoculated intranasally in Balb/c mice. Mouse survival was 40% with Pisum sativum and Canavalia ensiformis and 20% with Galanthus nivalis amebic pretreatment, compared with 0% survival for control animals administered trophozoites without pretreatment. Possibly some of the glycoproteins found in Naegleria fowleri represent an adherence factor. Differences in the saccharide sequences of the Naegleria species, even on the same glycoconjugate structure, could explain the different results corresponding to the distinct pretreatments (C. ensiformis, G. nivalis, and P. sativum). We found a higher expression of glycoconjugates recognized by P. sativum in Naegleria lovaniensis than N. fowleri, probably due to the higher number of oligosaccharides containing an α-1,6-linked fucose moiety expressed on the former species.

Naegleria fowleri after 50 years: is it a neglected pathogen?

“…Another in vitro study demonstrated the differential carbohydrate expression of N. fowleri and N. gruberi (CervantesSandoval et al, 2010). These findings were supported by those of Carrasco-Yepez et al (2013), who reported that mannose residues are essential for N. fowleri to adhere to mouse nasal mucosa.…”

Identification of differential protein recognition pattern between Naegleria fowleri and Naegleria lovaniensis

“…However, a 70‐kDa immunoreactivity protein species was found at a higher level for N fowleri ; suggesting that such differences exhibited a higher level of attachment to ECM components in N fowleri than N lovaniensis. 2 Other studies have demonstrated the differential carbohydrate expression of N fowleri and N gruberi suggesting that these differences are essential for N fowleri to adhere to mouse nasal mucosa 26,27 As we can observe, some of these pathogenicity factors are not exclusive to N fowleri , since they are also present in nonpathogenic Naegleria species with different level of expression 1,2,13,26,27 . While other virulence factors have only been studied in N fowleri and not in nonpathogenic Naegleria species .…”

“…About carbohydrates, there are reports that have shown that these participate in a very important way during the protozoan invasion process 69‐71 . In vitro experiments have shown that the trophozoites of N fowleri have high levels of glycoconjugates on their surfaces, mainly α‐ d ‐glucose, α‐ d ‐mannose, N ‐acetylneuraminic acid and terminal α‐L‐fucose residues, 26,72,73 and in vivo experiments have demonstrated the possibility that some of the glycoproteins found in N fowleri represent a factor of adherence to host cells 27 . As these glycoproteins identified in N fowleri could represent key adhesion factors to the nasal epithelium and probably would be important factors in the progression of the disease.…”

“…Naegleria fowleri ATCC 30808 and N lovaniensis ATCC 30569 were cultured axenically at 37°C in Bacto‐Casitone broth (225930; Difco) supplemented with 10% bovine serum (16170‐078; GIBCO) according to the method described previously by Carrasco‐Yepez et al 27 …”

“…Twenty microgram of total extracts from N fowleri and N lovaniensis were separated by SDS‐PAGE (12%) in denaturing conditions at 100 V. Subsequently, some gels were electroblotted (400 mA for 1 hour) onto a nitrocellulose membrane for Western blotting and others were stained with Coomassie blue until the appropriate contrast was achieved for band identification 27 …”