茄病镰刀菌致ICR小鼠局部皮肤感染的实验研究

目的建立茄病镰刀菌感染皮肤的ICR小鼠模型。方法将茄病镰刀菌三个不同浓度的菌悬液分别接种于正常和免疫抑制ICR小鼠受损及正常未受损的皮肤,于接种后第7、14、21、28天处死动物,取皮疹和各脏器进行真菌镜检、培养和组织病理学检查。结果正常和免疫抑制组皮肤受损的小鼠均出现皮疹,而免疫抑制组皮疹程度重,持续时间长,且真菌镜检、培养及组织病理学大都可见菌丝。皮肤未受损的小鼠不发生皮疹。实验小鼠均未出现系统播散。结论接种109CFU/mL或1010CFU/mL茄病镰刀菌的孢子悬液于免疫抑制ICR小鼠擦伤的皮肤,可有效造成ICR小鼠的茄病镰刀菌皮肤感染。     

Modeling Intercellular Interactions in Early Mycobacterium Infection

Infection with Mycobacterium tuberculosis (Mtb) is characterized by localized, roughly spherical lesions within which the pathogen interacts with host cells. Containment of the infection or progression of disease depends on the behavior of individual cells, which, in turn, depends on the local molecular environment and on contact with neighboring cells. Modeling can help us understand the nonlinear interactions that drive the overall dynamics in this system. Early events in infection are particularly important, as are spatial effects and inherently stochastic processes. We describe a model of early Mycobacterium infection using the CyCells simulator, which was designed to capture these effects. We relate CyCells simulations of the model to several experimental observations of individual components of the response to Mtb.     

我国实验小鼠群中巨细胞病毒自然感染情况的调查

迄今为止,有关MCMV在实验小鼠群中的自然感染情况报道极少。我们在MCMV实验感染的基础上对国内常用的小鼠品系进行MCMV自然感染的调查。结果发现在334份不同品系小鼠颌下腺中无1份分离出MCMV,而特异性抗体存在于所检查的10个品系中,阳性率为10.9—87.5％。抗体阳性率与鼠龄有关,随鼠龄的增长而上升。对全国部分省市40家实验动物机构的556份小鼠血清的调查结果表明MCMV的抗体阳性率达61.0％,提示在我国实验小鼠群中MCMV的自物感染是相当普遍的。这种病毒分离阴性而抗体阳性的状态表明隐性感染和潜伏感染是MCMV自然感染的主要方式。     

Role of Macrophages in Acute Murine Cytomegalovirus Infection

It has been recognized that macrophages play an important role in controlling virus infection in experimental animal models. To evaluate the role of macrophages in acute murine cytomegalovirus infection, macrophages in the spleen and the liver were eliminated by an intravenous injection of liposomes containing a cytolytic agent, dichloromethylene diphosphonate. The depletion of macrophages led to a significant increase of virus titer in the spleen and lungs in both susceptible BALB/c and resistant C57BL/6 mice during the first three days after intravenous infection. In the spleen, the increase of virus titer in macrophage-depleted BALB/c mice was much greater than that in NK cell-depleted mice. These results suggest that macrophages contribute to protection mainly by the mechanisms which are independent of NK cells during the first three days after infection. The increase of virus titer in macrophage-depleted C57BL/6 mice was as great as that in NK cell-depleted mice because of the high contribution of NK cells to protection in C57BL/6 mice. In the liver in both strains of mice, the effects of macrophage depletion on virus titer were not as much as those in the spleen and lungs. Furthermore, the local depletion of peritoneal macrophages resulted in a great increase of virus titer in the spleen at three days after intraperitoneal infection. We conclude that macrophages greatly contribute to decreasing the virus load in some organs possibly through either or both intrinsic and extrinsic mechanisms in the early phase of primary infection with murine cytomegalovirus.     

Origin of Polysaccharide Depolymerase Associated with Bacteriophage Infection

Analyses, by construction of phage growth curves, indicated that the polysaccharide depolymerase was synthesized by Pseudomonas aeruginosa strains B and BI after infection with phage 2. The kinetics of biosynthesis of the depolymerase were found to parallel closely the rate of formation of phage-directed virions, and alterations in the experimental conditions of infection were reflected by alterations in the production of enzyme. Infection with other Pseudomonas phages, 84 and 1197, did not result in the synthesis of depolymerase. The enzyme was not detectable in uninfected cultures, and no evidence was obtained for the existence of inhibitors or activators of enzyme activity in extracts of uninfected or infected cells. The results of experiments employing chloramphenicol or an auxotorphic mutant (BI arg(-)) suggested that protein synthesis de novo was essential for production of the enzyme. Various mutants of phage 2 (pdp(1), pdp(2)), which alter the synthesis of the polysaccharide depolymerase, have been isolated. These experimental results strongly support the role of the phage genome in the synthesis of this enzyme.     

宠物犬和猫流感病毒感染

近十年来犬和猫流感病毒感染报道迅速增多,不仅威胁到犬和猫的健康,也对公共卫生造成了影响。自2004年首次发生H3N8亚型流感病毒感染赛犬事件以来,犬流感一直在美国的赛犬和宠物犬中流行。在韩国和我国南方的犬群中出现了因H3N2亚型禽流感感染引起的肺炎病例。亚洲和欧洲均报道了猫H5N1亚型高致病性禽流感致死性感染病例,还通过实验研究发现H5N1亚型流感病毒可在猫与猫之间水平传播。这些现象预示着流感病毒进一步获得了感染哺乳动物的能力,其公共卫生意义需引起关注。为此,本文对犬和猫流感病毒感染的流行病学、临床症状、发病机制、诊断和防控措施进行了综述。     

Corynebacterium Pseudotuberculosis Infection in Goats VI.

Twelve kids, 5 1/2 months old, were inoculated intravenously with about 1 million colony forming units of a Corynebacterium pseudotuberculosis strain isolated from goat. Nine of the animals had antibodies against the organism in the bacterial agglutination test and/or the hemolysis inhibition test before they were inoculated. Four kids developed acute toxemia and died 2–5 days after the inoculation. Three of these animals were negative in both the bacterial agglutination test and the hemolysis inhibition test, while the fourth was positive in the bacterial agglutination test only. Post mortem examination revealed severe icterus, anemia, hemoglobinuria and acute pneumonia with microabscess formation in 3 of the kids that died. Eight animals, all with antibodies against C. pseudotuberculosis, developed acute illness but survived the inoculation. These animals were sacrificed and examined post mortem 1 month after the experimental infection, and abscesses were demonstrated in internal organs in all cases. It is concluded that intravenous inoculation with C. pseudotuberculosis is not a suitable challenge system to study the prophylactic efficacy of vaccines against caseous lymphadenitis in goats.     

沙门菌- 斑马鱼感染模型用于Th1/Th2 免疫应答的研究

目的:通过构建斑马鱼成鱼感染模型,研究鼠伤寒沙门菌感染对机体Th1/Th2免疫应答的影响。方法:用不同剂量细菌口饲感染8月龄的斑马鱼成鱼,绘制3周生存率曲线。观察各剂量下对成鱼的感染情况,并用实时荧光定量聚合酶链式反应检测肝脏Th1、Th2型细胞相关基因和细胞因子的mRNA转录水平,计算Th2/Th1相对表达量比值。结果:用105 CFU感染2周斑马鱼全部存活,第15天开始出现死亡,且在3周后死亡率达到50%;感染后3周解剖发现,肝脏、脾脏和肠道有明显红肿和糜烂;肝脏Th1、Th2型细胞相关基因和细胞因子mRNA转录水平明显向Th2偏移。结论:用105 CFU鼠伤寒沙门菌口饲感染斑马鱼成鱼构建的模型,能反映机体感染和免疫功能变化,可用于研究体内Th1/Th2免疫应答,为进一步研究鼠伤寒沙门菌感染与免疫机制提供了很好的实验工具。     

Gastric Infection with Kazachstania heterogenica Influences the Outcome of a Helicobacter suis Infection in Mongolian Gerbils

Background:  The Mongolian gerbil model is often used to investigate the interactions between different gastric Helicobacter species and the gastric tissue. A preliminary screening of a gerbil population intended for use in Helicobacter suis infection studies revealed a natural yeast infection in the stomach of these animals. After identification, we have investigated the effect of the gastric yeast infection on the outcome of an experimental H. suis infection in Mongolian gerbils.
Materials and methods:  Yeast cells were isolated from the stomachs of Mongolian gerbils. Identification was done by Internally Transcribed rRNA Spacer 2 Region PCR fragment length analysis. To investigate a possible pathologic role of this yeast, Mongolian gerbils were infected experimentally with this yeast. Co-infection with the newly isolated H. suis was performed to investigate possible interactions between both micro-organisms.
Results:  Kazachstania heterogenica was found colonizing the stomach of Mongolian gerbils, mainly in the antrum. Few pathologic changes were seen in the stomachs of infected animals. Experimental co-infection of gerbils with this yeast and the newly isolated H. suis showed a significant increase in inflammation in animals infected with both micro-organisms compared to animals infected only with H. suis .
Conclusions:  K. heterogenica colonizes the stomach of Mongolian gerbils in exactly the same regions as gastric Helicobacter species. The uncontrolled presence of this yeast in the gerbil stomach can lead to an overestimation of the inflammation caused by Helicobacter in this animal model.     

卡氏肺孢子虫感染小鼠动物模型的研究

采用肾上腺皮质激素的方法在国产昆明小鼠成功诱导卜氏肺孢子虫感染,在54只实验鼠中,47只发现虫体,阳性率为87．03％,表明该方法可透用于建立卡氏肺孢子虫感染的小鼠动物模型,并具有简便,经济等优点。     

Stimulation of Nonspecific Host Resistance to Infection Induced by Muramyldipeptides

The effect of muramyldipeptide (MDP), N-acetylmuramyl-l-alanyl-d-isoglutamine [MDP(Ala)], and its analogs on bacterial infection was studied using the experimental model of sepsis infection in mice. Injection of MDP(Ala) gave mice definitive protection against E. coli infection, but only partial protection against P. aeruginosa or K. pneumoniae infection. Several factors influencing the protective activity of MDP (Ala) on E. coli infection were studied, and it was demonstrated that the activity was induced by various routes of administration of MDP(Ala), including the oral route, and was markedly influenced by the bacterial inoculum size. It was also shown that the effective dose of MDP(Ala) was 100 μg per mouse for intraperitoneal, intravenous or subcutaneous injections and 1,000 μg per mouse when administered orally. Furthermore, the optimal interval between MDP-treatment and infection was 24 hr when the treatment was carried out before infection. Clearance of bacterial cells in blood was observed after E. coli infection in mice treated with MDP(Ala). The efficacy of MDP(Ala) and two analogs, N-acetylmuramyl-l-valyl-d-isoglutamine [MDP(Val)] and N-acetylmuramyl-l-seryl-d-isoglutamine [MDP (Ser)], was evaluated for the E. coli infection; MDP(Val) was proven to be slightly less active than MDP(Ala), and MDP(Ser) to be the least effective, although MDP(Val) or MDP(Ser) was reported to have higher adjuvanticity than MDP (Ala) for the development of delayed-type hypersensitivity.     

Group A Rotavirus Infection and Age-Dependent Diarrheal Disease in Rats: a New Animal Model To Study the Pathophysiology of Rotavirus Infection

Group A rotaviruses are major pathogens causing acute gastroenteritis in children and animals. To determine if group A rotavirus replicates and induces disease in rats, antibody-negative Lewis neonatal or adult rats were inoculated orally with tissue culture-adapted human (Wa, WI61, and HAL1166), simian (rhesus rotavirus [RRV] and SA11), bovine (WC3), lapine (ALA), or porcine (OSU) rotavirus strains, wild-type murine (EC(wt)) rotavirus strain, or phosphate-buffered saline (PBS). Rotavirus infection in rats was evaluated by (i) clinical findings, (ii) virus antigen shedding or infectious virus titers in the feces or intestinal contents measured by enzyme-linked immunosorbent assay or fluorescent-focus assay, (iii) histopathological changes in the small intestine, (iv) distribution of rotavirus antigen in small-intestine sections by immunofluorescence, and (v) growth rate. Rotavirus infection of 5-day-old but not > or =21-day-old rats resulted in diarrhea that lasted from 1 to 10 days postinoculation. The severity of disease and spread of infection to naIve littermates differed depending on the virus strain used for inoculation. The duration of virus antigen shedding following infection was considerably prolonged (up to 10 days) in neonatal rats compared to that in 21-day-old rats (1 or 2 days). Based on lack of virus antigen shedding and disease induction, the murine EC(wt) rotavirus was the only strain tested that did not infect rats. Histopathological changes in the small-intestine mucosa of 5-day-old RRV-inoculated rats but not of PBS-inoculated rats was limited to extensive enterocyte vacuolation in the ileum. In RRV-inoculated neonatal rats, rotavirus antigen was detected in the epithelial cells on the upper half of the intestinal villi of the jejunum and ileum. In addition, infection of neonatal rats with RRV but not with PBS resulted in reduced weight gain. Rats infected with group A rotaviruses provide a new animal model with unique features amenable to investigate rotavirus pathogenesis and the molecular mechanisms of intestinal development, including physiological factors that may regulate age-dependent rotavirus-induced diarrhea.     

Kinetics of Leptospira interrogans Infection in Hamsters after Intradermal and Subcutaneous Challenge

Background

Leptospirosis is a zoonosis caused by highly motile, helically shaped bacteria that penetrate the skin and mucous membranes through lesions or abrasions, and rapidly disseminate throughout the body. Although the intraperitoneal route of infection is widely used to experimentally inoculate hamsters, this challenge route does not represent a natural route of infection.

Methodology/Principal Findings

Here we describe the kinetics of disease and infection in hamster model of leptospirosis after subcutaneous and intradermal inoculation of Leptospira interrogans serovar Copenhageni, strain Fiocruz L1-130. Histopathologic changes in and around the kidney, including glomerular and tubular damage and interstitial inflammatory changes, began on day 5, and preceded deterioration in renal function as measured by serum creatinine. Weight loss, hemoconcentration, increased absolute neutrophil counts (ANC) in the blood and hepatic dysfunction were first noted on day 6. Vascular endothelial growth factor, a serum marker of sepsis severity, became elevated during the later stages of infection. The burden of infection, as measured by quantitative PCR, was highest in the kidney and peaked on day 5 after intradermal challenge and on day 6 after subcutaneous challenge. Compared to subcutaneous challenge, intradermal challenge resulted in a lower burden of infection in both the kidney and liver on day 6, lower ANC and less weight loss on day 7.

Conclusions/Significance

The intradermal and subcutaneous challenge routes result in significant differences in the kinetics of dissemination and disease after challenge with L. interrogans serovar Copenhageni strain Fiocruz L1-130 at an experimental dose of 2×10⁶ leptospires. These results provide new information regarding infection kinetics in the hamster model of leptospirosis.     

Corynebacterium Pseudotuberculosis Infection in Goats I.

The bacterial agglutination test (BAT) and the hemolysis inhibition test (HIT) were employed and evaluated. The threshold value between positive and negative antibody titres in BAT and HIT was determined on the basis of titration results for sera from 25 adult goats infected with Corynebacterium pseudotuber-culosis (positive), and sera from 25 adult goats from a herd in which caseous lymphadenitis did not occur (negative). Antibody titres were expressed as logio to the reciprocal value of the highest positive serum dilution in both tests. Positive titre (T) in BAT was stipulated as T ≥ 2.1 and in HIT as T > 0.6. The sensitivity and specificity was 0.96 in both tests in the material used. Twenty-three of the 25 goats infected with G. pseudotuberculosis were positive in both BAT and HIT. The reproducibility in both tests was described by the use of correlation coefficient and coefficient of variation. The values were estimated using duplicate determination of titres of 155 serum samples. Correlation coefficients were 0.87 for BAT and 0.95 for HIT. Coef-ficients of variation were 26.4 % for BAT and 14.1 % for HIT. The coefficient of variation was related to titres. It was highest for BAT at low titres. It was concluded that both tests can be used for seroepidemio-logical investigations of C. pseudotuberculosis infection in goats.     

Dynamics of Dual Infection with Campylobacter jejuni Strains in Chickens Reveals Distinct Strain-to-Strain Variation in Infection Ecology

Although multiple genotypes of Campylobacter jejuni may be isolated from the same commercial broiler flock, little is known about the infection dynamics of different genotypes within individuals or their colonization sites within the gut. Single experimental infections with C. jejuni M1 (sequence type 137, clonal complex 45) and C. jejuni 13126 (sequence type 21, clonal complex 21) revealed that 13126 colonized the ceca at significantly higher levels. The dissemination and colonization sites of the two C. jejuni strains then were examined in an experimental broiler flock. Two 33-day-old broiler chickens were infected with M1 and two with 13126, and 15 birds were left unchallenged. Cloacal swabs were taken postinfection to determine the colonization and shedding of each strain. By 2 days postinfection (dpi), 8/19 birds were shedding M1 whereas none were shedding 13126. At 8 dpi, all birds were shedding both strains. At 18 dpi, liver and cecal levels of each isolate were quantified, while in 10 birds they also were quantified at nine sites throughout the gastrointestinal (GI) tract. 13126 was found throughout the GI tract, while M1 was largely restricted to the ceca and colon. The livers of 7/19 birds were culture positive for 13126 only. These data show that 13126 has a distinctly different infection biology than strain M1. It showed slower colonization of the lower GI tract but was more invasive and able to colonize at a high level throughout the GI tract. The finding that C. jejuni strains have markedly different infection ecologies within the chicken has implications for control in the poultry industry and suggests that the contamination risk of edible tissues is dependent on the isolate involved.     

Meta-analysis of the Effects of Insect Vector Saliva on Host Immune Responses and Infection of Vector-Transmitted Pathogens: A Focus on Leishmaniasis

A meta-analysis of the effects of vector saliva on the immune response and progression of vector-transmitted disease, specifically with regard to pathology, infection level, and host cytokine levels was conducted. Infection in the absence or presence of saliva in naïve mice was compared. In addition, infection in mice pre-exposed to uninfected vector saliva was compared to infection in unexposed mice. To control for differences in vector and pathogen species, mouse strain, and experimental design, a random effects model was used to compare the ratio of the natural log of the experimental to the control means of the studies. Saliva was demonstrated to enhance pathology, infection level, and the production of Th2 cytokines (IL-4 and IL-10) in naïve mice. This effect was observed across vector/pathogen pairings, whether natural or unnatural, and with single salivary proteins used as a proxy for whole saliva. Saliva pre-exposure was determined to result in less severe leishmaniasis pathology when compared with unexposed mice infected either in the presence or absence of sand fly saliva. The results of further analyses were not significant, but demonstrated trends toward protection and IFN-γ elevation for pre-exposed mice.     

儿童泌尿系感染的病原学分析

探讨目前儿童泌尿系感染病原体的变化趋势,为临床治疗提供实验依据。分析2008年1月至2009年10月住院治疗的357例尿细菌培养、支原体体外培养、衣原体检测阳性的泌尿系感染患儿病原体的分布情况。结果显示,尿细菌培养和支原体体外培养、衣原体检测前未应用过抗生素的患儿其阳性率为82.2%,而应用过抗生素的患儿其阳性率为31.8%,两者相比具有统计学意义(P0.01)。在检测的357例阳性标本中,革兰阴性杆菌占74.7%,其中以大肠埃希菌为主,占46.2%;革兰阳性球菌占14.8%,其中肠球菌占10.9%;真菌占3.1%,支原体占4.8%,衣原体占2.5%。临床要密切关注儿童泌尿系感染病原体的分布变迁情况,以便于为临床的诊断和治疗提供可靠的实验依据。     

Infection of procaryotic and eucaryotic microorganisms withMetallogenium

To elucidate the biological characteristics ofMetallogenium, a study was undertaken into the effect of infection of such organisms unable to oxidize manganese as fungi, yeasts, and bacteria with an ultrafiltrate of this organism on the subsequent behavior of the resulting binary cultures. The infection of microorganism cultures is accompanied by (a) acquisition by the binary cultures of a persistent capacity to oxidize manganese, (b) evolution of the characteristic structures ofMetallogenium (c) inhibition of the growth of the inoculated cultures; the inhibition manifests itself by fungi losing their capacity for spore formation and pigmentation, the upsetting of cell division processes, and lysis of the cells of the infected cultures all the way to death. When a heated ultrafiltrate ofMetallogenium was used to infect microorganism cultures, no signs of infection were detected.Metallogenium may be hosted by an extremely broad range of microorganisms that are in no way allied to one another. The experimental results suggest thatMetallogenium is an organism capable of parasitizing lower eucaryotic and procaryotic microorganisms. Analysis of 134 strains of fungi isolated from freshwater bodies is indicative of possible parasitism ofMetallogenium on microorganisms in their natural habitats.