Comparison of acute Mycobacterium tuberculosis infection mouse models established by different infection routes / 中华传染病杂志

ABSTRACT

ObjectiveTo compare three types of acute Mycobacterium tuberculosis infection mouse models established through different infection routes and to set up the theoretical basis for further developing,selecting and applying these animal model in the tuberculosis-related research.MethodsStandard strain of Tubercle bacillus H37Rv was diluted to 1 × 106 colony forming unit (cfu)/mL.The mice were infected with the bacteria through different routes including intravenous injection,intranasal administration and inhalation of bacteria aerosol.Six weeks after the infection,the mice were euthaniz ed and necropsied. The lung tissues were collected and gross changes were observed.The colony counting was performed and the lung tissues were assessed by HE staining,acid fast staining.The e xpression level of tumor necrosis factor (TNF)-α per unit area in lung tissue was detected by immunohistochemistry. The data were analyzed by t test. Results The amounts of Mycobacterium tuberculosis in lung tissues of mice in inhalation group,intranasal administration group and intravenous injection group were (6.290±0.028),(6.150±0.021) and (6.120±0.008) lg cfu/mL,respectively; while no Mycobacterium tuberculosis was detected in control group. The difference between infection group and control group was statistically significant (t =3.762,P＜0.01),while there were no significant differences among infection groups with different infection routes (P＞0.05).According to the results of gross observations and histological assessment,the pathological changes were observed and red tubercle bacillus was detected by acid-fast staining in the lung tissues of all the mice in infection group.The results of immunohistochemistry showed that the expression levels of TNF-α per unit area were as follows:intravenous injection group (0.049 × 106 )＜intranasal administration group(0.759×106) ＜ inhalationgroup(1.042×106), whichwere statistically different (t =2.504,P＜ 0.05).ConclusionInhalation of bacteria aerosol may be the most efficient method to establish tuberculosis infection mouse model compared to intravenous injection and intranasal administration.