A rapid, parasite-dependent cellular response to Dirofilaria immitis in the Mongolian jird (Meriones unguiculatus).

BACKGROUND: The Mongolian jird (Meriones unguiculatus) has long been recognized as a permissive host for the filarial parasite Brugia malayi; however, it is nonpermissive to another filarial parasite, canine heartworm (Dirofilaria immitis). By elucidating differences in the early response to infection, we sought to identify mechanisms involved in the species-specific clearance of these parasites. We hypothesized that the early clearance of D. immitis in intraperitoneal infection of the jird is immune mediated and parasite species dependent. METHODS: Jird peritoneal exudate cells (PECs) were isolated and their attachment to parasite larvae assessed in vitro under various conditions: D. immitis and B. malayi cultured separately, co-culture of both parasites, incubation before addition of cells, culture of heat-killed parasites, and culture with PECs isolated from jirds with mature B. malayi infection. The cells attaching to larvae were identified by immunohistochemistry. RESULTS: In vitro cell attachment to live D. immitis was high (mean = 99.6%) while much lower for B. malayi (mean = 5.56%). This species-specific attachment was also observed when both filarial species were co-cultured, with no significant change from controls (U(9, 14) = 58.5, p = 0.999). When we replicated these experiments with PECs derived from jirds subcutaneously infected with B. malayi, the results were similar (99.4% and 4.72% of D. immitis and B. malayi, respectively, exhibited cell attachment). Heat-killing the parasites significantly reduced cell attachment to D. immitis (mean = 71.9%; U(11, 14) = 7.5, p < 0.001) while increasing attachment to B. malayi (mean = 16.7%; U(9, 15) = 20, p = 0.002). Cell attachment to both species was reduced when larvae were allowed a 24-h pre-incubation period prior to the addition of cells. The attaching cells were identified as macrophages by immunohistochemistry. CONCLUSIONS: These results suggest a strongly species-dependent response from which B. malayi could not confer protection by proxy in co-culture. The changes in cell attachment following heat-killing and pre-incubation suggest a role for excretory/secretory products in host immune evasion and/or antigenicity. The nature of this attachment is the subject of ongoing study and may provide insight into filarial host specificity.

Effects of air temperatures on antioxidant defense and immunity in Mongolian gerbils.

Temperature influences many physiological processes including antioxidant defense and immunity. The hypothesis that air temperatures has no effects on antioxidant defense and innate immunity in Mongolian gerbils (Meriones unguiculatus) was tested. Thirty-three male gerbils were randomly divided into the 4 °C (n = 11), 23 °C (n = 11) and 32 °C groups (n = 11), in which the treatment course lasted for 27 days. We found that air temperatures had no effects on body mass. At lower temperature, gross energy intake and the masses of most organs were higher, whereas fat free dry carcass and body fat were lower. H2O2 titres increased in liver but decreased in small intestine, and remained unchanged in heart, kidney and testis upon cold exposure. At lower temperature, malonaldehyde (MDA) content was higher in the liver, lower in kidneys and testis, and did not differ in the heart and small intestine. The activities of superoxide dismutase (SOD), total antioxidant capacity (T-AOC) in liver were higher in 4 °C group than 23 °C group, while liver catalase (CAT) activity was lower in the 4 °C group than in the 23 °C group. No significant difference was observed in the activities of SOD, CAT and T-AOC in the heart, kidney, testis and small intestine among the 4 °C, 23 °C and 32 °C groups. As expected, bacteria killing capacity indicating innate immunity, white blood cells and thymus mass were all not affected by air temperatures. Similarly, air temperatures had no effect on the levels of testosterone and corticosterone, both of which were not correlated with innate immunity, H2O2 and MDA levels, the activity of SOD, CAT, and T-AOC in all the detected tissues. In conclusion, air temperature affected antioxidant capacity, but not immune responses or serum concentrations of corticosterone and testosterone. Overall, up-regulation or maintenance of antioxidant defenses and immunity might be an important mechanism for gerbils to survive highly variable temperature.

Neospora caninum bioassay in gerbils using placental tissues from naturally infected goats.

Neospora caninum is one of the main agents that causes abortions in cattle worldwide. However, little is known about the pathogenesis of neosporosis in small ruminants, especially goats. Gerbils (Meriones unguiculatus) have been used as a model for neosporosis, and this species is highly susceptible to infection by bovine N. caninum strains. The present study aimed to evaluate the susceptibility of gerbils to a N. caninum isolate from goats. The placentas were obtained from naturally infected goats, that presented with mild to severe lymphoplasmacytic and histiocytic infiltrate, foci of necrosis, calcification and protozoan-like structures. Immunosuppressed gerbils bioassayed with N. caninum-infected placental tissues showed severe neurological signs. Microscopic lesions in these gerbils were characterized by encephalitis, myocarditis, myositis and pancreatitis. These lesions were often associated with a small to moderate number of N. caninum tachyzoites, confirmed by immunohistochemistry and PCR. This is the first report showing that goat N. caninum strains could infect immunocompetent gerbils and cause severe lesions and clinical signs in immunosuppressed gerbils.

[Dynamics of F1 antibody responses to Yersinia pestis infection in Rhombomys opimus].

Objective: To observe the dynamics of antibody response in great gerbils infected with Yersinia pestis in experiment. Method: A total of 211 great gerbils were captured in the southern margin of plague natural focus of Junggar Basin of the Xinjiang Uygur Autonomous Region in 2011. Among them, there were 167 great gerbils without infection of Y. pestis and 44 great gerbils infected by Y.pestis. Y.pestis No. 2504 was employed for this experimental strain, which was strong toxic strain with negativity in the reduction experiment of nitrate. 35 great gerbils without the infection of Y. pestis were divided randomly and averagely into 7 groups including 6 experimental groups and 1 control group. Great gerbils in the 1st to 6th experimental groups were exposed first with 1 × 10(6)-1 × 10(11) CFU/ml of bacterial fluid with 10 times of gradient dilution; groin areas of great gerbils in the control group were injected subcutaneously with physiological saline; and the amount of infection was all 1 ml. 17 great gerbils infected with Y. pestis and the first detection of F1-antibody titer in 1∶256-1∶4 096 were grouped according to F1-antibody titer: group 1∶4 096 (n=4), group 1∶2 048 (n=4), group 1∶1 024 (n=3), group 1∶512 (n=3) and group 1∶256 (n=3); and blood in caudal regions was collected in asepsis for the detection of F1-antibody, with a total of 5 times. 9 great gerbils which were selected from the remaining great gerbils infected with Y. pestis and detected F1-antibody negative 2 times were exposed 1×10(6) CFU/ml of bacterial fluid for the second infection, with the amount of infection being 1 ml. Blood in caudal regions of great gerbils after the first and second infection were collected for the detection of plague F1-antibody on the 3rd, 5th, 7th, 15th, 30th, 60th, 90th and 120th day after infection. Declined regression models for great gerbils' antibodies were established with unary linear regression equation; declined change diagrams for the antibodies were drawn to observe the declined F1-antibody after great gerbils were exposed to Y. pestis. Results: In great gerbils with the first infection of Y. pestis, antibodies were detected in the 1 × 10(6)-1 × 10(8) CFU/ml of group on the 30th, 15th and 15th day, respectively; the positive rates of antibody were 1/4, 3/4 and 4/5, respectively; the group 1×10(7) and 1× 10(8) CFU/ml reached to the highest antibody titer with 1∶256 on the 120th day; antibodies were revealed in the group 1×10(9), 1×10(10) and 1×10(11) CFU/ml from the 5th to 7th day when the seroconversion of all antibodies was observed; group 1×10(11) CFU/ml reached to the highest antibody titer on the 120th day with 1∶4 096. In the great gerbils with the second exposure to Y.pestis, positive antibodies were detected on the 3rd day with the positive rate being 2/9; and the highest antibody titer with 1∶2 048 was noted on the 90th day. Unary linear regression equation of declined F1 antibody of great gerbils was y=0.045x- 0.321 (F=115.40, P< 0.001), and the shortest duration for F1-antibody titer declining from 1∶4 096 to 0 was 140 d and the longest duration 200 d. Conclusion: Great gerbils infected with the high concentration of Y. pestis fluid show shorter duration in producing F1-antibody, the antibody positive rate is also higher, and the highest antibody titer can reach 1∶4 096. The great gerbils could hold the plague F1 antibodies for a long time which was about 140 to 200 days from the highest titer.

IL-20 contributes to low grade inflammation and weight gain in the Psammomys obesus.

The metabolic syndrome has been demonstrated in gene deficient animals, e.g. db/db mice, to include a systemic inflammation leading to insulin resistance, obesity and type 2 diabetes (T2D). To determine the importance of inflammation in obesity and diabetes, in a normal non-genetically modified species, an intervention study with neutralizing anti-IL-20 antibodies was conducted in the spontaneous T2D model Psammomys obesus. All IL-20 receptor chains were expressed on protein level in the Psammomys obesus. Neutralization of IL-20 did not modulate blood glucose, HbA1c, insulin levels or lymphocyte numbers after five weeks treatment although a trend to reduced weight gain rate was observed upon anti-IL-20 treatment. Inhibition of IL-20 significantly increased the number of CD11bhigh/low cells and the CD11bGr-1int myeloid derived suppressor cells in the spleen. Importantly, although the number of M1-like monocytes remained unchanged the M1-like marker CD11c expression level was reduced on the cells upon anti-IL-20 treatment. Anti-IL-20 treatment reduced both TLR4 and CCR2b expression on the macrophages upon treatment. Further, a marked shift in the protein signature in the pancreatic tissue after anti-IL-20 treatment was observed including enhanced expression of CXCL12, TIMP-1 and IL-10 while IL-1ß, CXCL4, PEDF and ADAMTS1 were reduced. In conclusion, we describe for the first time the systemic immune response in the diabetic Psammomys obesus. Neutralizing IL-20 modulated the myeloid compartment, the adaptive immunity, and local expression of proteins in the diabetic pancreatic tissue as well as improved on weight gain and hence may place IL-20 as a cytokine to be considered in obesity.

[Experimental observation on the histopathological and ultrastructural pathology of Great Gerbils (Rhombomys opimus) in the Junggar Basin by subcutaneous injecting of Yersinia pestis].

Objective: To understand the histopathological and ultrastructural pathology changes of great gerbils in the Junggar Basin to Yersinia pestis infection. Methods: Forty captured great gerbils from the Junggar Basin that tested negative for anti-F1 antibodies were infected. The Y. pestis strain 2504, isolated from a live great gerbil in the natural plague foci of the Junggar Basin in 2005 with a median lethal dose (LD(50)) of <10 CFU/ml, was used in this study. Forty great gerbils were divided into seven infection groups and were subcutaneously infected with 7.4×10(5), 7.4×10(6), 7.4×10(7), 7.4×10(8), 7.4×10(9), 7.4×10(10), or 3.0×10(11) CFU/ml of 2504. One milliliter of physiological saline was injected in the noninfected group as a control. We collected the liver, spleen, heart, and lung from all animals for histopathologic and ultrastructural pathology examination. Results: Great gerbils in the 7.4×10(8)-3.0×10(11) CFU/ml groups did not survive and exhibited pathological changes and altered ultrastructural pathology. The liver tissue of infected great gerbils showed spotty necrosis and fatty degeneration, intranuclear canaliculi with increased hepatocytes, and uneven distribution of organelles. Additionally, reactive proliferation of lymphoid tissue in the spleen, blood sinusoid lacunae with neutrophil infiltration, and phagocytosed bacteria in phagocyte cells were observed. Myocardial fiber hypertrophy and interstitial indistinction, nuclear matrices decreased in cardiac myocytes, and loose arrangement of myogenic fibers in myocardial cells were also observed. Angiectasia, capillary congestion, and tissue necrosis were found in the lung. No significant difference in histopathological and ultrastructural pathology in the parenchymal organ was observed between the 7.4×10(5)-7.4×10(7) CFU/ml groups and the 7.4×10(8)-3.0×10(11) CFU/ml groups, and no specific death caused by Y. pestis infection was apparent in the 7.4×10(5)-7.4×10(7) CFU/ml groups. Conclusion:Y. pestis infection altered tissue and ultrastructural pathology in the parenchyma apparatus of great gerbils. In particular, the liver and spleen appeared to be the primary site of Y. pestis infection in great gerbils.

Enterovirus 71 infection causes severe pulmonary lesions in gerbils, meriones unguiculatus, which can be prevented by passive immunization with specific antisera.

Neurogenic pulmonary edema caused by severe brainstem encephalitis is the leading cause of death in young children infected by Enterovirus 71 (EV71). However, no pulmonary lesions have been found in EV71-infected transgenic or non-transgenic mouse models. Development of a suitable animal model is important for studying EV71 pathogenesis and assessing effect of therapeutic approaches. We had found neurological disorders in EV71-induced young gerbils previously. Here, we report severe pulmonary lesions characterized with pulmonary congestion and hemorrhage in a gerbil model for EV71 infection. In the EV71-infected gerbils, six 21-day-old or younger gerbils presented with a sudden onset of symptoms and rapid illness progression after inoculation with 1×105.5 TCID50 of EV71 via intraperitoneal (IP) or intramuscular (IM) route. Respiratory symptoms were observed along with interstitial pneumonia, pulmonary congestion and extensive lung hemorrhage could be detected in the lung tissues by histopathological examination. EV71 viral titer was found to be peak at late stages of infection. EV71-induced pulmonary lesions, together with severe neurological disorders were also observed in gerbils, accurately mimicking the disease process in EV71-infected patients. Passive transfer with immune sera from EV71 infected adult gerbils with a neutralizing antibody (GMT=89) prevented severe pulmonary lesion formation after lethal EV71 challenge. These results establish this gerbil model as a useful platform for studying the pathogenesis of EV71-induced pulmonary lesions, immunotherapy and antiviral drugs.

Dynamics of Yersinia pestis and its antibody response in great gerbils (Rhombomys opimus) by subcutaneous infection.

BACKGROUND: Rhombomys opimus (great gerbil) is a reservoir of Yersinia pestis in the natural plague foci of Central Asia. Great gerbils are highly resistant to Y. pestis infection. The coevolution of great gerbils and Y. pestis is believed to play an important role in the plague epidemics in Central Asia plague foci. However, the dynamics of Y. pestis infection and the corresponding antibody response in great gerbils have not been evaluated. In this report, animal experiments were employed to investigate the bacterial load in both the liver and spleen of infected great gerbils. The dynamics of the antibody response to the F1 capsule antigen of Y. pestis was also determined. METHODOLOGY: Captured great gerbils that tested negative for both anti-F1 antibodies and bacterial isolation were infected subcutaneously with different doses (10(5) to 10(11) CFU) of a Y. pestis strain isolated from a live great gerbil during routine plague surveillance in the Junggar Basin, Xinjiang, China. The clinical manifestations, changes in body weight, anal temperature, and gross anatomy of the infected animals were observed. The blood cell count, bacterial load, and anti-F1 antibody titers were determined at different time points after infection using a blood analyzer, plate counts, and an indirect hemagglutination assay, respectively. CONCLUSIONS/SIGNIFICANCE: The dynamics of bacterial load and the anti-F1 antibody concentration in great gerbils are highly variable among individuals. The Y. pestis infection in great gerbils could persist as long as 15 days. They act as an appropriate reservoir for plague in the Junggar Basin, which is part of the natural plague foci in Central Asia. The dynamics of the Y. pestis susceptibility of great gerbil will improve the understanding of its variable resistance, which would facilitate the development of more effective countermeasures for controlling plague epidemics in this focus.

Isotype analysis of gerbil-mouse heterohybridomas by RT-PCR.

We designed primer sets specific to the immunoglobulin (Ig) heavy-chain constant region (IGHC) genes in Mongolian gerbil (Meriones unguiculatus) to amplify five gerbil IGHC cDNA sequences, Cµ, Cγ1, Cγ2, Cε, and Cα. Five gerbil-mouse heterohybridomas B11D2(C2), B11E2(D5).M, B5-3, D5, and C11 respectively expressed Cγ1, Cµ, Cγ2, Cγ2, and Cγ1. In contrast, a commercial isotyping kit for mouse Igs identified Cγ1, Cµ, Cγ3, Cγ3, and Cγ1, respectively, misidentifying gerbil IgG2 as IgG3 by cross-reactivity with anti-mouse IgG3 polyclonal antibody. These primer sets will allow the accurate estimation of gerbil Ig classes and IgG subclasses. These results from three gerbil strains indicate that the primer sets can be used for isotype analysis of gerbil mAbs and for evaluation of humoral immunity.

Impairment of cellular and humoral immunity in overweight Mongolian gerbils (Meriones unguiculatus).

Animal immunity is usually impaired in obesity. We know little about the effect of being overweight or obese on the immune function of wild rodents. The present study is aimed to test the hypothesis that immunity is suppressed in overweight Mongolian gerbils (Meriones unguiculatus). In the study, 16 overweight (body mass: 90.8-127.6 g) and 16 lean gerbils (body mass: 60.5-77.7 g) were randomly selected from a total of 174 male gerbils (body mass range: 55.8-144.7 g). Half of the overweight and lean males were injected with sterile saline; the others were immunochallenged (IC) with phytohaemagglutinin and keyhole limpet hemocyanin to assess cellular and humoral immunity, respectively. Body fat mass, wet and dry spleen mass, leukocyte counts, blood glucose levels and serum leptin levels were significantly higher in the overweight gerbils than in the lean gerbils. However, phytohemagglutinin response indicative of cellular immunity and immunoglobulin G concentrations was significantly lower in the IC overweight gerbils than in the IC lean gerbils. These results indicate that cellular and humoral immunity are impaired in the overweight gerbils. Excessive body fat mass, higher leukocyte counts and serum leptin levels imply that overweight gerbils are in a low grade inflammatory state.

Glucose supplement reverses the fasting-induced suppression of cellular immunity in Mongolian gerbils (Meriones unguiculatus).

Glucose plays an important role in immunity. Three day fasting will decrease cellular immunity and blood glucose levels in Mongolian gerbils (Meriones unguiculatus). In the present study, we tested the hypothesis that glucose supplement can reverse the fasting-induced suppression in cellular immunity in gerbils. Twenty-eight male gerbils were selected and randomly divided into fed and fasting groups. Half of the gerbils in each group were then provided with either 10% glucose water or pure water. After 66 h, each gerbil was injected with phytohaemagglutinin (PHA) solution to challenge cellular immunity. Results showed that glucose supplement restored blood glucose levels in fasted gerbils to those of the fed controls. It also recovered cellular immunity, body fat mass and serum leptin levels in fasted gerbils to the values of the fed controls. Blood glucose levels were positively correlated with body fat mass, leptin levels and cellular immune responses. Thymus and spleen masses, and white blood cells in fasted gerbils were not affected by glucose supplement. In general, our data demonstrate that glucose supplement could reverse fasting-induced suppression of cellular immunity in Mongolian gerbils.

Establishment of gerbil-mouse heterohybridoma secreting immunoglobulin of Mongolian gerbil (Meriones unguiculatus) establishment of gerbil-mouse heterohybridoma.

Hybridomas, generated by fusing myeloma cells with B lymphocytes, secrete monoclonal antibodies (mAbs) specific for an antigen. To establish hybridomas that secrete Mongolian gerbil (Meriones unguiculatus) mAbs, we immunized gerbils with keyhole limpet hemocyanin (KLH) and fused splenocytes from them with a non-secreting mouse myeloma cell line (P3-X63-Ag8.653). We obtained hybridomas that secreted immunoglobulin (Ig) against KLH. These hybridomas had more chromosomes than either parent and retained several gerbil chromosomes. Therefore, these cells were heterohybridomas with both gerbil and mouse chromosomes. They expressed gerbil Ig heavy-chain constant (IGHC) region mRNA, but not mouse gamma (γ) 1 IGHC. SDS-PAGE and Western blot analyses indicated that the cells secreted whole Ig molecules of gerbil origin. Moreover, the cells continued secreting Ig for several months.

A combination of two Brugia malayi filarial vaccine candidate antigens (BmALT-2 and BmVAH) enhances immune responses and protection in jirds.

In this study filarial recombinant protein or DNA vaccine constructs encoding BmALT-2 and BmVAH as single or as cocktail antigens were evaluated. Male jirds were immunized intramuscularly with DNA vaccine constructs or were immunized intraperitoneally with protein vaccine. The single and bicistronic DNA constructs induced substantial interferon-γ responses in spleen cells; antigen-specific responses were higher following immunization with the bicistronic cocktail construct and evoked a significant protective response of 57% in jirds challenged with Brugia malayi that was similar in the antibody-dependent cellular cytotoxicity (ADCC) assay and micropore chamber experiment. The cocktail protein vaccines induced a mixture of IgG2a (Th1) and IgG1 (Th2) responses with 80% protective response when challenged with B. malayi infective larvae. However, the single protein vaccine rALT-2 induced Th2 (IgG1/IgG3) with a 70% protective response and rVAH induced Th1 (IgG2a) with a lower proliferative response with 60% protection following challenge with B. malayi infective larvae. These results suggest that filarial cocktail protein vaccines are able to elicit substantial immune and protective responses when compared with single antigen vaccination in suitably vaccinated jirds.

Food restriction and refeeding have no effect on cellular and humoral immunity in Mongolian gerbils (Meriones unguiculatus).

Small mammals in the temperate area often face fluctuations in food availability. Changes in food availability may have a great influence on an animals' immunity, which is important to their survival. We tested the hypothesis that cellular and humoral immunity would be suppressed by food restriction and restored to control levels by refeeding in Mongolian gerbils Meriones unguiculatus. Forty adult male gerbils were randomly divided into food-restricted (80% of baseline food intake) and food ad lib. groups. Similarly, another 40 adult male gerbils were also randomly assigned to two groups: a group for which food was restricted for 36 d and then provided ad lib. and a group that was continuously fed ad lib. Half of the gerbils in each group were injected with phytohemagglutinin (PHA) and keyhole limpet hemocyanin solution to assess cellular and humoral immunity, respectively; the others were injected with sterile saline as control groups. Food-restricted gerbils had significantly lower body mass, body fat mass, dry thymus mass, wet and dry spleen mass, and serum leptin levels than those of the controls, whereas refeeding restored these parameters to the controls. Both food restriction and refeeding had no significant effect on PHA response indicative of cellular immunity, immunoglobulin G and immunoglobulin M concentrations, and white blood cells. We also found that food restriction decreased corticosterone levels in food-restricted gerbils, while refeeding increased corticosterone levels in refed gerbils compared with the controls. Our results suggest that cellular and humoral immunity were not affected by food restriction and refeeding in gerbils.

Phylogenetic status of Pneumocystis from corticosteroid-treated gerbils.

Pneumocystis spp. infect the lungs of multiple mammalian species and cause disease in immunosuppressed individuals. The Pneumocystis isolates that have been studied to date fall into two major clades, those from primates and those from rodents. Within each of these clades, different species have been described on the basis of host specificity and differences in sequence and morphology. Here, we demonstrate that dexamethasone immunosuppression consistently results in histologically apparent lung infection in gerbils (28/35 animals). Sequence analysis of the 18S, 5.8S and internal transcribed spacer regions of the rDNA and a portion of the mitochondrial large subunit rDNA demonstrated that this gerbil Pneumocystis is grouped with other rodent Pneumocystis spp., but is distinct from them. Our results suggest that gerbil Pneumocystis differs sufficiently from Pneumocystis species found in other rodents to be considered a separate species.

Fasting suppresses T cell-mediated immunity in female Mongolian gerbils (Meriones unguiculatus).

Immune defense is important for organisms' survival and fitness. Small mammals in temperate zone often face seasonal food shortages. Generally fasting can suppress immune function in laboratory rodents and little information is available for wild rodents. The present study tested the hypothesis that Mongolian gerbils (Meriones unguiculatus) could inhibit T cell-mediated immunity to adapt to acute fasting. Forty-two females were divided into the fed and fasted groups, in which the latter was deprived of food for 3days. After 66h fasting, half of the gerbils in each group were injected with phosphate buffered saline or phytohaemagglutinin (PHA) solution. T cell-mediated immunity assessed by PHA response was suppressed in the fasted gerbils compared with the fed gerbils. The fasted gerbils had lower body fat mass, wet and dry thymus mass, dry spleen mass, white blood cells, serum leptin and blood glucose concentrations, but higher corticosterone concentrations than those of the controls. Moreover, PHA response was positively correlated with body fat mass and serum leptin levels in the immunochallenged groups. Taken together, acute fasting leads to immunosuppression, which might be caused by low body fat mass and low serum leptin concentrations in female Mongolian gerbils.

Detection of the antibody to lymphocytic choriomeningitis virus in sera of laboratory rodents infected with viruses of laboratory and newly isolated strains by ELISA using purified recombinant nucleoprotein.

An enzyme-linked immunosorbent assay (ELISA) was developed to detect the antibody against lymphocytic choriomeningitis virus (LCMV) in sera of laboratory animals. In this ELISA system, LCMV-nucleoprotein (NP) expressed by recombinant baculovirus and purified with high molar urea was used as the antigen. Sera from laboratory animals experimentally infected with the Armstrong strain or the newly isolated M1 strain of LCMV were examined to detect anti-LCMV antibody by the ELISA system, and the reactivity was compared with that of IFA test. Regardless of LCMV strain, all the sera of adult mice infected with LCMV were positive with very high optical density (OD). Also, the sera from mice neonatally infected with LCMV M1 strain were positive with slightly lower OD than adult mice. In contrast, all the sera of uninfected mice were negative to LCMV-NP antigen. Similarly, anti-LCMV antibodies were detected in all the sera of hamsters, mastomyses, and gerbils infected with the LCMV Armstrong strain. The results of the ELISA were in complete agreement with those of IFA, and indicate the high sensitivity and specificity of the ELISA system in the detection of anti-LCMV antibody. Because this ELISA system does not require handling infectious LCMV in the course of the antigen preparation and serological assay, there is no risk of contamination in the laboratory or nearby animal facility. In addition, by using negative control antigen in parallel with positive antigen in ELISA, we can exactly check the LCMV contamination in laboratory animals.

Citrus auraptene reduces Helicobacter pylori colonization of glandular stomach lesions in Mongolian gerbils.

We examined the efficacy of auraptene (AUR), an antioxidant agent of a citrus coumarin derivative, for suppressing gastric inflammation introduced by Helicobacter pylori (Hp) infection in Mongolian gerbils (MGs). Hp-infected MGs were placed on diets containing 100 or 500 ppm AUR for 7 weeks. Real-time PCR was used to estimate the Hp population in glandular stomach lesions, and a histological assessment of inflammation was performed. At a dose of 500 ppm, AUR reduced the Hp population to 21.9+/-12.0% of the control group (p<0.05). However, no apparent differences were seen in hematoxylin and eosin sections between AUR-administered and control groups. We conclude that dietary supplementation with 500 ppm of AUR suppresses Hp colonization, but does not reduce gastric inflammation.

Statistical analysis of the dynamics of antibody loss to a disease-causing agent: plague in natural populations of great gerbils as an example.

We propose a new stochastic framework for analysing the dynamics of the immunity response of wildlife hosts against a disease-causing agent. Our study is motivated by the need to analyse the monitoring time-series data covering the period from 1975 to 1995 on bacteriological and serological tests-samples from great gerbils being the main host of Yersinia pestis in Kazakhstan. Based on a four-state continuous-time Markov chain, we derive a generalized nonlinear mixed-effect model for analysing the serological test data. The immune response of a host involves the production of antibodies in response to an antigen. Our analysis shows that great gerbils recovered from a plague infection are more likely to keep their antibodies to plague and survive throughout the summer-to-winter season than throughout the winter-to-summer season. Provided the seasonal mortality rates are similar (which seems to be the case based on a mortality analysis with abundance data), our finding indicates that the immune function of the sampled great gerbils is seasonal.