Early Trichinella spiralis and Trichinella nativa infections induce similar gene expression profiles in rat jejunal mucosa

Trichinella spiralis causes a significantly higher parasite burden in rat muscle than Trichinella nativa. To assess whether the difference in infectivity is due to the early intestinal response, we analyzed gene expression changes in the rat jejunum during Trichinella infection with a whole-genome microarray. The rats were euthanized on day five of infection, and their jejunal mucosa was sampled for microarray analysis. In addition, intestinal histology and hematology were examined. Against our expectations, the gene expression changes were similar in both T.nativa- and T. spiralis-infected groups. The two groups were hence pooled, and in the combined Trichinella-infected group, 551 genes were overexpressed and 427 underexpressed when compared to controls (false discovery rate ?0.001 and fold change at least 2 in either direction). Pathway analysis identified seven pathways significantly associated with Trichinella infection (p < 0.05). The microarray data suggested nonspecific damage and an inflammatory response in the jejunal mucosa. Histological findings, including hyperemia, hemorrhage and a marked infiltration of inflammatory cells, supported the microarray data. Trichinella infection caused complex gene expression changes that indicate a host response to tissue damage in the mucosa of the jejunum, but the changes were not notably dependent on the studied species of Trichinella.     

Immunity to Trichinella spiralis in irradiated mice

Irradiation prevented the accelerated expulsion of Trichinella spiralis from mice immunized by transfer of immune mesenteric lymph node cells (IMLNC) or by prior infection. Nevertheless, worms in irradiated immune mice were smaller and less fecund than those in controls. In adoptively immunized and irradiated mice expulsion could not be achieved by increasing the numbers of IMLNC transferred, although the effect upon worm length was more severe. Thus IMLNC express a direct, anti-worm immunity which is independent of their role in worm expulsion. IMLNC cause expulsion in irradiated mice only when adequate levels of bone marrow-derived cells are available. The results are discussed in terms of a possible antibody-mediated basis for direct anti-worm immunity.     

Comparison of rapid expulsion of Trichinella spiralis in mice and rats

Alizadeh H. and Wakelin D. 1982. Comparison of rapid expulsion of Trichinella spiralis in mice and rats. International Journal for Parasitology12: 65–73. Primary infections of Tricliinella spiralis in both NIH mice and Wistar rats resulted in increased levels of mucosal mast cells and goblet cells. In mice the numbers of both cell types rose sharply before worm expulsion (days 8–10), remained at an increased level for a short time and declined quickly, reaching control levels on day 14 for goblet cells and between days 28 and 35 for mast cells. In contrast, in rats, the numbers of goblet cells and mast cells increased during worm expulsion and remained above control levels for a prolonged period. Challenge infections given shortly after expulsion of a primary infection (day 14) were expelled rapidly, worm loss being virtually complete with 24 h. In mice this response to challenge was short-lived and persisted only until day 16 after primary infection. After this time, challenge worms were expelled more slowly after infection. In rats the rapid expulsion response was expressed for at least 7 weeks after primary infection. Mice and rats showed differences in the conditions of infection necessary to prime for rapid expulsion, mice requiring larger and longer duration primary infections, but the expression of the response appeared to be similar in both species. In mice it was shown that rapid expulsion of T. spiralis was a response evoked specifically by prior infection with this species; infections with other intestinal nematodes had no effect. Similarly, the effect upon challenge infection was also specific to T. spiralis. The rapidity with which challenge infections are expelled suggests that either the specific inflammatory changes generated during primary infection result in an environment that is unsuitable for establishment of subsequent infections or that challenge infections provide a stimulus that can provoke an almost instantaneous response in the primed intestine. The relationship of the observed cellular changes to such mechanisms is discussed.     

旋毛虫肌幼虫细胞传代培养及超微结构观察

消化、分离观察旋毛虫(Trichinella spiralis)肌幼虫,获得肌幼虫细胞,用含10%胎牛血清的RPMI-1640培养液培养原代细胞,胰酶(含0.02?TA)消化法进行传代,透射电镜观察培养细胞超微结构,用多重PCR鉴定培养细胞。结果表明,在培养24～72h原代细胞开始贴壁,7～8d形成单层细胞,细胞间融合现象不明显,10～12d传一代。透射电镜显示旋毛虫细胞核为椭圆形,核膜、核仁清晰,核内染色质较丰富,胞浆含丰富的线粒体。细胞主要有两种类型:椭圆形和多角形,以椭圆形为主。多重PCR扩增培养细胞DNA,可见1条与旋毛虫肌幼虫DNA扩增产物相同的条带(173bp)。结果表明,旋毛虫肌幼虫细胞可在含10%胎牛血清的RPMI-1640培养液中传代培养。     

Interactions between Trichinella spiralis and Hymenolepis nana in the intestine of the mouse

Ferretti G., Gabriele F., Palmas C. and Wakelin D. 1984. Interactions between Trichinella spiralis and Hymenolepis nana in the intestine of the mouse. International Journal for Parasitology14: 29–33. The rejection of the intestinal phase of Trichinella spiralis in outbred CD₁ mice is associated with an inflammatory response. The effects of this inflammation were studied in mice concurrently infected with an unrelated parasite, Hymenolepis nana, which stimulates a slight inflammation but is also immunologically rejected by this strain of mice. Moreover though Cd(In)1 mice seem to be ‘slow responders’, in concurrent infections with T. spiralis and H. nana there was a marked effect upon the cesode survival. At the highest level of T. spiralis infection, H. nana failed to establish at all. On the other hand, if 300 T. spiralis were administered 10 weeks earlier, H. nana become established in all mice and the distribution of parasites suggests that immunodepression is involved. An accelerated loss of the nematode, when H. nana was present, was also demonstrated. There was no evidence of any reciprocal or specific cross-immunity between the two parasites.     

Response of nonsensitized and sensitized lactating mice to infection with Trichinella spiralis

The effect of lactation on the expulsion of adult Trichinella spiralis were studied in: (1) lactating, (2) induced agalactic post-parturient, (3) previously sensitized, and (4) mice sensitized during lactation. The results indicated that lactation was associated with an altered pattern of worm expulsion; i.e. more adult worms were recovered from nonsensitized and sensitized lactating mice than from control mice. Furthermore, neither mice sensitized before nor during lactation demonstrated an immunity to challenge infection.     

Within-host dynamics of Trichinella spiralis predict persistent parasite transmission in rat populations

Trichinella spiralis is transmitted and maintained in both a domestic and sylvatic cycle, whereby rats contribute to the spread of T. spiralis from domestic to sylvatic animals and vice versa. As a model for T. spiralis transmission in wildlife, we studied the potential of rats to act as a reservoir species for T. spiralis, by assessing experimentally its within-host infection dynamics, and simulating the between-host dynamics by a Monte Carlo approach. The distribution of parasite burden in individual rats is mathematically defined by roots of the dose response equation intersecting with the diagonal. In simulated between-host dynamics, up to 10⁴ events of uninterrupted parasite transmission were observed. Histograms of parasite burdens per individual rat matched closely with the mixture of two gamma distributions, which were derived from the within-host infection dynamics. In conclusion, T. spiralis transmission persists in a population of rats when they cannibalize their own species. Rats should be included in the minimal set of wildlife species that maintain the life cycle of T. spiralis.     

Tissue eosinophil numbers and phospholipase B activity in mice infected with Trichinella spiralis

Wilkes S. D. and Goven A. J. 1984. Tissue eosinophil numbers and phospholipase B activity in mice infected with Trichinella spiralis. International Journal for Parasitology14. 479–482. Tissue eosinophils were counted and phospholipase B activity was assayed in the intestines of mice infected with 200 Trichinella spiralis larvae. The numbers of intestinal eosinophils and phospholipase B activity increased, peaked and returned to normal levels during the same time period. The findings support the hypothesis that a parasite-induced tissue eosinophilia is the source of elevated phospholipase B activity present in parasitized tissues.     

Concepts of nematode-fungus associations in plant disease complexes: a review

Plant parasitic nematodes interact with fungi in a variety of ways to cause plant disease complexes. Even some nonplant parasitic nematodes are able to carry fungal spores internally which not only increases their mobility, but also protects them from fungicides. Plant parasitic nematodes frequently wound plants in the process of penetration and feeding. These wounds become subject to infection by fungal pathogens that require aid in penetrating their host. Other nematodes modify plant tissue in such a way that it becomes a better substrate for the fungus and thus increases their growth and reproduction to the detriment of the host. Quantitative and qualitative changes in root exudate which are induced by certain nematodes stimulate the germination, growth, and reproduction of fungal propagules in the rhizosphere. These exudates may also indirectly inhibit components of the rhizosphere microflora (e.g., actinomycetes) which are antagonistic to some plant pathogens. Depending on the species of nematode and fungus, concomitant infections may stimulate nematode reproduction (Pratylenchus-Verticillium) or inhibit reproduction (Heterodera-Fusarium).     

Trichinella spiralis: Differential effect of host bile on the in vitro invasion of infective larvae into epithelial cells

The differential effect of fox and pig bile and its corresponding low molecular weight fraction (LMW) was investigated on the in vitro invasion of MDCK-AA7 epithelial cell monolayers by Trichinella spiralis muscle larvae. Seven invasion experiments were performed and a total of 274 cell monolayers were examined. Fox and pig raw bile at 1:10 and 1:20 dilution and their LMW fractions at 1:10 dilution activated T. spiralis larvae to invade the cell monolayers. In addition, fox raw bile caused significantly larger cell damage than pig raw bile at both dilutions. The area of cell damage was larger at 1:10 than at 1:20 dilution for both fox and pig raw bile (p < 0.05). On the other hand, there was no significant difference between the areas of cell damage caused by the LMW fractions of fox and pig bile. It is concluded that differences between host bile actions may account for differences in host susceptibility to T. spiralis.     

Trichinella spiralis: Growth of the intracellular (muscle) larva

Newborn larvae of Trichinella spiralis were infective when injected directly into the thigh muscle of mice and rats. Infections initiated in this manner resulted in synchronously growing populations of muscle larvae, thereby permitting a detailed study of larval growth to be carried out.In mice, the mean larval growth, as measured by increase in larval volume, occurred in three phases; an initial growth phase (Day 0–1), a lag phase (Days 1–3), and an exponential growth phase (Days 3–19). Larvae grew an average of 39% per day during the exponential phase.No further increase in larval volume was noted after Day 19. There was no statistically significant difference found in the rate of larval growth among individual mice for any given day. The larval growth rate was the same in rats as in mice.     

The location of parasites within their hosts: Factors affecting longitudinal distribution of Trichinella spiralis in the small intestine of mice

Inocula of encysted larvae, excysted larvae or infected meat all resulted in aggregated distributions of adults in the anterior small intestine. However, implantation studies indicated that the larvae could establish anywhere between the duodenum and the colon. The site of larval establishment determines the subsequent location of adult T. spiralis; the site of establishment was due largely to influences such as intestinal motility, size of inoculum and the size of the vehicle of infection. Predominantly female inocula were dispersed similarly to heterosexual inocula while male populations were dispersed more widely.     

Trypanosoma musculi and Trichinella spirails: Concomitant infections and selection for resistance genotypes in mice

Trypanosoma musculi infections were given to mice of different strains before, at the same time, and after an infection with 400 Trichinella spiralis. Examined parameters of the host response to T. spiralis were worm rejection, antifecundity responses, development of immunological memory, and muscle larvae burden. After dual infection, each mouse strain showed characteristic effects on resistance to T. spiralis. This was due to a dynamic interaction between the genes controlling rejection of T. spiralis and those influencing T. musculi growth. C3H mice develop high trypanosome parasitemias. This impairs worm expulsion and the development of memory to T. spiralis when Trypanosoma infections take place on the same day or 7 days before. The C57B1/6 mouse develops low parasitemias and T. musculi infections on the same day, or 7 days before T. spiralis, delaying worm rejection only slightly despite the overall weak capacity of B6 mice to expel worms. NFR-strain mice are strong responders to T. spiralis and also develop low parasitemias. Trypanosome infections on the same day, or after T. spiralis, produce a delay in worm rejection; the former is comparable to C3H mice. However, NFR mice alone showed enhanced rejection of worm when T. musculi infections preceded T. spiralis by 7 days. An unusual feature of C3H mice was that T. musculi infections 7 days before T. spiralis increased antifecundity responses at the same time that worm expulsion was inhibited. Trypanosome infections can therefore modulate distinct antihelminth immune responses in different directions simultaneously. The different outcomes of dual infections compared with single infections provides another selective mechanism by which genetic polymorphisms can be established and maintained in the vertebrate host.     

Characterization of an in vitro proliferation response to solubilized Trichinella spiralis antigens: Role of Ia antigens and Ly-1+ T cells

An antigen extract from Trichinella spiralis muscle larvae was prepared and used to immunize strains of mice which were either relatively resistant (B10.S) or susceptible (B10.BR) to oral infection with T. spiralis larvae. Proliferation of cells from the draining lymph nodes was then measured in vitro after stimulation with the T. spiralis extract as well as appropriate control antigens. Primed cells from resistant B10.S mice responded better to challenge than did cells from the susceptible B10.BR strain. Cell-depletion experiments involving B10.S cells indicated that the in vitro cell proliferation response is dependent upon Ly-1⁺ T cells. The data were also consistent with a requirement for Ly-1⁺, -2⁺, and -3⁺ amplifier cells. Administration of anti-I^s serum to the cultures specifically inhibited (nearly 75%) the cell proliferation response. The potential applications of this system as a tool in immunogenetic analyses of immunity to T. spiralis are discussed.     

Allergic inflammation as a hypothesis for the expulsion of worms from tissues: A review

Introduction; comparison of studies of mice infected with Trichinella spiralis; discussion; summary; references.     

Activation of Leishmania (Leishmania) amazonensis arginase at low temperature by binuclear Mn center formation of the immobilized enzyme on a Ni resin

In Leishmania, arginase is responsible for the production of ornithine, a precursor of polyamines required for proliferation of the parasite. In this work, the activation kinetics of immobilized arginase enzyme from L. (L.) amazonensis were studied by varying the concentration of Mn²⁺ applied to the nickel column at 23 °C. The intensity of the binding of the enzyme to the Ni²⁺ resin was directly proportional to the concentration of Mn²⁺. Conformational changes of the enzyme may occur when the enzyme interacts with immobilized Ni²⁺, allowing the following to occur: (1) entrance of Mn²⁺ and formation of the metal bridge; (2) stabilization and activation of the enzyme at 23 °C; and (3) an increase in the affinity of the enzyme to Ni²⁺ after the Mn²⁺ activation step. The conformational alterations can be summarized as follows: the interaction with the Ni²⁺ simulates thermal heating in the artificial activation by opening a channel for Mn²⁺ to enter.     

Eimeria nieschulzi and Trichinella spiralis: Analysis of concurrent infection in the rat

The effects of concurrent primary infection of the rat with Eimeria nieschulzi and Trichinella spiralis on the number of oocysts of E. nieschulzi shed by the host and on the number, distribution, and fecundity of adult T. spiralis were analyzed. When rats were initially infected with E. nieschulzi followed 9 days later by infection with T. spiralis there occurred a significant decrease in the total numbers of adult worms in the small intestine, a significant shift in the position of these worms along the length of the small gut, a decrease in the fecundity of adult female worms, and a decrease in muscle parasitism when compared with rats infected with T. spiralis alone. When rats were initially infected with T. spiralis, followed 9 days later by infection with E. nieschulzi, there occurred a significant decrease in the numbers of oocysts shed over 24 hr on Days 7, 9, and 11 postinfection below that seen with rats infected only with Eimeria. These changes are discussed in terms of the enteropathophysiologic lesions and enteric inflammation known to occur during infections with these two parasites.     

Identification of the spectral characteristics of submerged plant Vallisneria spiralis

The relationship between land features and their spectral characteristics is important for the interpretation of remote sensing images. In this study, the spectral characteristics of a submerged plant Vallisneria spiralis with varied coverage was measured with a ground sensor/radiometer, FieldSpec^TM Pro JR Spectroradiometer in the laboratory and in the constructed wetland of “Mengqingyuan”, Shanghai, China. The results showed that the reflectance rate of Vallisneria spiralis rose with its increasing coverage, which was exhibited both at the visible band (500–650 nm) and the near infrared band (700–900 nm). Water quality influenced the reflectance rate with the primary differences between the laboratory and field experiments mainly occurring at the near-infrared band (700–900 nm). A regression analysis was carried out respectively between the coverage of Vallisneria spiralis and the reflectance rate at the wavelengths of Quick Bird 4 bands where the coverage responded to the strongest. These results of regression analyses showed a clear linear relationship, by which the coverage of Vallisneria spiralis could be quantitatively deduced from the reflectance rate measured in situ. The implications in terms of the ability of hyperspectral remote sensing to distinguish and monitor the distribution and dynamics of submerged vegetation on a large scale are discussed.     

Identification of the spectral characteristics of submerged plant Vallisneria spiralis

The relationship between land features and their spectral characteristics is important for the interpretation of remote sensing images. In this study, the spectral characteristics of a submerged plant Vallisneria spiralis with varied coverage was measured with a ground sensor/radiometer, FieldSpec? Pro JR Spectroradiometer in the laboratory and in the constructed wetland of “Mengqingyuan”, Shanghai, China. The results showed that the reflectance rate of Vallisneria spiralis rose with its increasing coverage, which was exhibited both at the visible band (500–650 nm) and the near infrared band (700–900 nm). Water quality influenced the reflectance rate with the primary differences between the laboratory and field experiments mainly occurring at the near-infrared band (700–900 nm). A regression analysis was carried out respectively between the coverage of Vallisneria spiralis and the reflectance rate at the wavelengths of Quick Bird 4 bands where the coverage responded to the strongest. These results of regression analyses showed a clear linear relationship, by which the coverage of Vallisneria spiralis could be quantitatively deduced from the reflectance rate measured in situ. The implications in terms of the ability of hyperspectral remote sensing to distinguish and monitor the distribution and dynamics of submerged vegetation on a large scale are discussed.