Establishment of a mouse model of cutaneous protothecosis / 中华皮肤科杂志

ABSTRACT

Objective To develop a mouse model of cutaneous protothecosis.Methods Totally,48 BALB/c mice were randomly and equally divided into four groupshigh-and low-concentration immunosuppressive groups-immunosuppressed mice inoculated with P.zopfii var.portoricensis suspension of 1 × 109 and 1 × 106 colony forming units (CFU) conidia/ml respectively,high-concentration healthy group-healthy mice inoculated with P.zopfii var.portoricensis suspension of 1 × 109 CFU conidia/ml,and control group-healthy mice inoculatedwith sodium chloride physiological solution.The P.zopfii suspension or sodium chloride physiological solution was subcutaneously inoculated to the abdominal skin of mice,with the inoculation volume being 200 μl.Skin appearance at the inoculation site was observed,and four mice were sacrificed in each group on day 7,14 and 28 after the inoculation.Skin specimens were resected from the inoculation sites of mice and subjected to pathological and mycological examinations.Results Mice in the three experiment groups inoculated with the P.zopfi suspension were all infected,with the appearance of papules and abscess at the inoculation sites of all mice as well as ulcer and crusts in some mice.Meanwhile,no mice were infected in the control group.Significant differences were noted in the diameter of skin lesions between the three time points in these experiment groups (all P ＜ 0.05),and the largest diameter of lesions was observed on day 7,which was (6.75 ± 1.09) mm in the high-concentration immunosuppressive group,(5.88 ± 1.17) mm in the low-concentration immunosuppressive group,and (5.96 ± 0.99) mm in the high-concentration healthy group.Comparisons of lesion diameter between the three experiment groups revealed a statistical difference on day 28 (F =8.91,P ＜ 0.05),with the largest lesion diameter observed in the high-concentration immunosuppressive group (4.38 ± 0.86 mm),but no statistical difference was found on day 7 or 14 (both P ＞ 0.05).Pathology of skin specimens consistently revealed necrosis,abscess and granuloma formation in the three experiment groups.Spores were found in the lesions of infected mice by haematoxylin-eosin staining,periodic acid-Schiff staining,and direct microscopy.Culture of tissue samples from the experiment groups grew Prototheca.Conclusion The mouse model of protothecosis can be established by subcutaneous inoculation of Prototheca suspension in the abdominal skin of healthy or immunosuppressed mice.