Prevalence of natural virus infections in laboratory mice and rats used in Canada

Results of serological tests carried out over a period of 6 years to detect the presence of antibodies against 14 indigenous viruses in mice and rats used in 32 Canadian institutions are reported. Close to 20,000 individual sera were tested by the complement fixation or the hemagglutination inhibition technics. In order of mouse colony prevalence the six most common viruses present were pneumonia virus of mice, mouse hepatitis virus, rat virus, minute virus of mice, Sendai, and Theiler's mouse encephalomyelitis viruses. The most common viruses present in rat colonies were minute virus of mice, K virus, coronaviruses (rat coronavirus or sialodacryoadenitis virus), rat virus, H-1, pneumonia virus of mice, Theiler's mouse encephalomyelitis viruses, Sendai, and reovirus 3.     

The case for genetic monitoring of mice and rats used in biomedical research

Currently, there is the potential to generate over 200,000 mutant mouse strains between existing mouse strains (over 24,000) and genetically modified mouse embryonic stem cells (over 209,000) that have been entered into the International Mouse Strain Resource Center (IMSR) from laboratories and repositories all over the world. The number of rat strains is also increasing exponentially. These mouse and rat mutants are a tremendous genetic resource; however, the awareness of their genetic integrity such as genetic background and genotyping of these models is not always carefully monitored. In this review, we make a case for the International Council for Laboratory Animal Science (ICLAS), which is interested in promoting and helping academic institutions develop a genetic monitoring program to bring a level of genetic quality assurance into the scientific interchange and use of mouse and rat genetically mutant models.     

Prevalence of nptII and Tn5 in kanamycin-resistant bacteria from different environments

Abstract Kanamycin (Km)-resistant bacterial populations in different soil, river water, sewage and pig manure slurry samples were enumerated and their prevalence in the total populations determined. About 350 Km-resistant Gram-negative colonies grown in the presence of kanamycin were identified using a rapid presumptive identification scheme. They were then screened for the presence of Tn5 and npt II sequences using hybridization of cells in dot blots, of Southern-blotted genomic DNA extracts and of PCR amplification products. Colonies reacting positively with a 2.7 kb probe of the central region of Tn5, or with a 925 bp npt II specific probe were primarily obtained from sewage samples, whereas fewer were obtained from pig manure slurry, river water and soil. However, in soil samples bacteria containing Tn5 or npt II were not found. Transposon Tn5 carrying the npt II gene could be unequivocally demonstrated in 3 isolates from sewage, identified as Aeromonas spp. (2x) and Escherichia coli . Hin dIII digests of chromosomal DNA obtained from these strains were cloned and shown to confer Km resistance to a sensitive E. coli strain. Further, various strains revealed the presence of npt II homologous sequences in a non-Tn5 background. The occurence of Tn5 and npt II in the samples was also assessed via PCR analysis of total community DNA extracts obtained from the aforementioned environmental samples. Evidence for the occurence of npt II was obtained for sewage, pig manure slurry, for 2 (out of 3) river water (Avon, Rhine) and 3 (out of 6) soil (Flevo silt loam, Westmaas silt loam, Ahlum rhizosphere) samples. Tn5 was not detectable via PCR in any of these environmental DNA extracts but it was found in Ede loamy sand and Flevo silt loam samples taken from a field microplot 2 and 4 weeks after release of a Tn5-containing genetically modified organism.     

The effect of air ions on bacterial and viral pneumonia in mice

Ambient air untreated for removal of ordinary pollutants and ionized with tritium powered generators to contain 1–2 × 10⁵ small positive ions/cm³ accelerated the rate of death of mice challenged intranasally with measured doses of KLEBSIELLA PNEUMONIAE or of the PR8 strain of influenza virus. The differences between the cumulative mortality rates of controls and ion-treated animals were significant (p < 0.05 to p < 0.001) for several days of the period of observation. Exposure of infected mice to an electrical field of the same strength as that used for ion-treated mice showed no statistically significant field effect. Repetition of the influenza virus experiments using pollutant-free air and ion densities averaging 4.1 × 10⁵ small positive ions/cm³ produced essentially the same results. The observation that high concentrations of positive ions accelerate the rate of death in pulmonary infections with KLEBSIELLA PNEUMONIAE and with influenza virus conforms to the pattern of earlier work with COCCIDIOIDES IMMITIS.

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Zusammenfassung Ungereinigte Umgebungsluft mit 1–2 × 10⁵ kleinen positiven Ionen/cm³ nach Ionisation mit Tritiumbetriebenen Generatoren beschleunigte die Todesrate von Mäusen, die intranasal mit bekannten Mengen KLEBSIELLA PNEUMONIAE und PR8 Influenza Virus okuliert worden waren. Die Unterschiede zwischen den Kontrolltieren und den ionenbehandelten Tieren waren an mehreren Beobachtungstagen signifikant (p < 0,05 bis p < 0,001). Die Exponierung der infizierten Tiere in einem elektrischen Feld der gleichen Stärke, wie für die ionenbehandelten Tiere verwendet wurde, ergab keine statistischen Unterschiede. Die Wiederholung der Versuche mit Influenza Virus in reiner Luft mit 4,1 × 10⁵ kleinen positiven Ionen/cm³ ergab die gleichen Ergebnisse.

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Resume De l'air non purifié additionné de 1–2 × 10⁵ petits ions positifs/cm³ — ions provenant de générateurs au Trititium — a augmenté le taux de décès de souris qu'on avait au préalable infectées par le nez de quantités déterminées de KLEBSIELLA PNEUMONIAE et de virus d'influenza PR8. La différence du taux cumulatif de mortalité entre des animaux traités avec cet air ionisé et des témoins a été significative pour chacun des jours de la période d'essais (p < 0,05 à p < 0,001). L'exposition de souris infectées à un champ électrique de même intensité que celui utilisé pour les animaux traités n'a pas présenté d'effets significatifs. La répétition de l'essai avec le virus de l'influenza, mais en utilisant de l'air libre de tout polluant et une densité d'ions moyenne de 4,1 × 10⁵ petits ions positifs/cm³ a conduit à des résultats similaires. La constatation que de hautes concentrations en ions positifs augmente le taux de décès dûs à des infections pulmonaires avec KLEBSIELLA PNEUMONIAE et avec le virus de l'influenza vient confirmer le résultat d'un essai antérieur pratiqué avec COCCIDIOIDES IMMITIS.

     

Enumeration of single IFN-gamma-producing cells in mice during viral and bacterial infection

A solid phase immunoenzymatic technique was employed for detecting single IFN-gamma-producing cells (IFN-gamma PC) in the mouse. After infection with lymphocytic choriomeningitis virus or Listeria monocytogenes, the numbers of IFN-gamma PC in spleens began to rise on day 4, attained maxima on days 7 and 8, and declined thereafter. Negative selection in vitro by use of mAb and C allowed phenotypic identification of the producer cells; most, if not all, carried Thy-1, and approximately one half expressed CD4, the other half, CD8. Depletion of cells in vivo by treatment of mice with mAb led to somewhat different results; again, anti-Thy-1 antibody eliminated essentially all IFN-gamma PC, but considerably more than 50% were either CD4+ or CD8+, suggesting regulatory interactions between these T lymphocyte subsets with regard to generation of the lymphokine.     

Cycloferon efficacy in viral and bacterial diseases of children (clinical review)

The authors' findings and literature data on the pharmacotherapeut efficacy of cycloferon, an interferon inductor (immunomodulators) are described. The drug effect in the treatment of various socially significant children' diseases, including acute respiratory tract viral infection, bronchial asthma, allergic conditions with infection protection disturbances, mycoplasmic infection, bronchopulmonary complications of acute respiratory tract viral infection with low intensity of free radical oxidation is indicated. The use of cycloferon at the background of vaccination was shown to provide inhibition of the autoimmune processes causing postvaccinal complications in frequently ill children. The results of the use of cycloferon in the treatment of gastrointestinal tract and intestinal infections of both the viral and bacterial genesis are discussed. Cycferon is recommended to be used for correction of the intestine dysbiosis (the microflora level came to normal in 95% of the children). The use of the drug in surgical pathology and in particular in appendicular peritonitis for decreasing the postoperative complications and correction of the immune disturbances due to chronic viral hepatitis C and B in children under the complex therapy is described. The cycloferon safety and efficacy were confirmed by the postmarketing randomized trials.     

Spontaneous vulvar papillomas in a colony of mice used for pancreatic cancer research

Mice in a colony used for pancreatic cancer research and maintained in a barrier animal facility presented with vulvar masses. A census and examination of all colony animals was conducted on 17 February 2006; line, gender, and mass location were recorded; a slide caliper was used to measure the width, length, and height of each mass; and the volume of each mass was calculated. Progeny female mice from crossbreeding of the B6.FVB-Tg(Ipf1-cre)1Tuv and B6;129-Kras2tm4Tyj (KRAS(G12D/+)) strains presented with external vulvar and periauricular papillomas. The papillomas were present in 41.2% of all female crossbred mice and ranged in size from 8 to 36 mm3. Age of mice and tumor size were not correlated. Compared with the B6.FVB-Tg(Ipf1-cre)1Tuv line, the crossbred female mice were more likely to have a vulvar mass, with an odds ratio of 29.3, 95% confidence interval (1.5, 563.9) and a positive predictive value of 42.9%. Diagnostic evaluation, including electron microscopy, light microscopy, serology, and bacteriology, did not reveal a viral or other infectious etiology. Therefore, we speculate that interaction between the genetic background of the mice and the introduced Kras oncogene may be responsible for these papillomas.     

常见SPF级小鼠和大鼠肠道菌群多样性研究

目的研究常见SPF级小鼠和大鼠的肠道菌群多样性。方法分别采集广东地区三家实验动物生产单位的C57BL/6、ICR、BALB/c小鼠和Wistar、SD大鼠的盲肠内容物样品,用细菌16S rDNA通用引物扩增V4-V5区域,采用Illumina Miseq 2×300 bp测序平台进行测序,使用生物信息学方法进行微生物群落分析、Alpha多样性分析与Beta多样性分析。结果对序列去杂优化后OTU聚类分析,稀释性曲线说明本次测序的数据量合理;实验小鼠和大鼠肠道菌群共分成八个门,其中拟杆菌门(Bacteroidetes)、厚壁菌门(Firmicutes)占据主要地位,属水平上主要是拟杆菌属(Bacteroides)、Hungatella、副杆状菌属(Parabacteroides)、乳酸杆菌属(Lactobacillus)等;样品间差异性分析显示相同设施来源动物的菌群组成相似性较高;Alpha分析结果显示来源于同种设施的动物物种丰富度相近;Beta分析显示相同设施动物的肠道菌群差异较小,但品系对肠道菌群差异性有所影响。结论不同来源设施的饲养环境是动物肠道菌群多样性的主要影响因素,不同品系对肠道菌群多样性有一定影响。     

Convergence to equilibrium states for a reaction-diffusion system modelling the spatial spread of a class of bacterial and viral diseases

A reaction-diffusion system which describes the spatial spread of bacterial diseases is studied. It consists of two nonlinear parabolic equations which concern the evolution of the bacteria population and of the human infective population in an urban community, respectively. Different boundary conditions of the third type are considered, for the two variables. This model is suitable to study oro-faecal transmitted diseases in the European Mediterranean regions. A threshold parameter is introduced such that for suitable values of it the epidemic eventually tends to extinction, otherwise a globally asymptotically stable spatially inhomogeneous stationary endemic state appears. The case in which the bacteria diffuse but the human population does not, has also been considered.Work performed under the auspices of the G.N.A.F.A. [L. M.] and the G.N.F.M. [V. C.] C.N.R. in the context of the Program of Preventive Medicine (Project MPP1), C.N.R., Italy     

Oral health status and change in handgrip strength over a 5-year period in 80-year-old people

Objective: The number of remaining teeth may indicate the extent of life‐long exposure to inflammation, a known risk factor for muscle loss and consequent disability. The aim was to study dental health status as a risk factor for muscle strength loss in very old people. Design: Cross‐sectional and prospective cohort study over a 5‐year follow‐up. Setting: Research laboratory. Participants: One hundred and ninety‐three 80‐year‐old people participated in the baseline examinations. Five years later, 79 survivors were retested. Main outcome measures: Number of remaining teeth, presence of periodontitis and handgrip strength. Results: At baseline, grip strength of men correlated positively with number of teeth but not with the presence of periodontitis. In women, the cross‐sectional associations were not statistically significant. In the prospective analyses, the presence of periodontitis at baseline showed a clear association with a steeper decline in handgrip over the 5‐year follow‐up in both sexes. The values adjusted for gender, height, weight, number of chronic conditions and physical activity were ?28.3% (SE 5.7) among those with periodontitis vs. ?11.9% (SE 3.1, p = 0.015) among those with healthy gingiva. No association between the number of teeth at baseline and change in grip strength over 5 years was observed. Conclusions: The presence of oral inflammation may lead to loss in muscle strength increasing the risk of disability. Therefore, good dental care throughout the life span may decrease risk of disability in old age.     

Minute virus of mice: antibody response, viral shedding, and persistence of viral DNA in multiple strains of mice

Minute virus of mice (MVM) is a major concern for laboratory animal facilities because it remains with considerably high prevalence despite strict barrier systems. The aim of this study was to elucidate potential risks associated with MVM infection by investigating the role of the genetic background on antibody production and persistence as well as viral shedding. Mice of various strains and stocks were inoculated oronasally with the immunosuppressive strain MVMi; in addition, natural infection was modeled through contact exposure. As determined by serology, seroconversion and serum levels of IgG differed considerably among strains and stocks, especially in the contact-exposed group. For example, C57BL/6J mice responded well to exposure in contrast to FVB/N, NMRI, ICR, and C3H/HeN mice. Titration studies indicated that the viral dose necessary to induce seroconversion was strain-dependent. Experiments to dissect the role of the major histocompatibility complex haplotype in the response to MVMi gave inconclusive results. To detect viral persistence, spleens and feces were analyzed by PCR at 16 wk after exposure, and the infectivity of PCR-positive spleens was investigated by IP and oronasal inoculation of naive mice. Although DNA was detected in the spleens of some mice, feces remained negative, and naive mice were not infected by inoculation. In addition, viral shedding declined rapidly after day 20 postinoculation. In summary, the data show that seroconversion and antibody response to MVMi infection depend on the genetic background of mice, with the infective dose being a critical factor. The role of viral DNA in chronically infected mice will require further elucidation.     

Genome recoding: a review of basic concepts,current research and future prospects of virus attenuation for controlling plant viral diseases

Plants are very susceptible to pathogens and every year, 25% of crop loss is caused by various types of pathogens including viruses. Many different strategies are being used for developing resistance against virus infection, including RNA silencing, and the genome editing including CRISPR-Cas-9 but these may produce variants/recombinants and could cause the problems for future crops. Another promising approach named as genome recoding or rewriting would be a better potential tool for controlling viral infections in plants. It relies on the concepts of replacement of synonymous codons, change in codon bias, codon pair bias and dinucleotide content. Recoding of the genome does not alter the amino acid sequences but it affects the expression level and translation efficiency. In the present report, the concept of synonymous codons, the basics of genome recoding and the possible strategies to generate genome recoded organisms are provided in details. Viral attenuation has been achieved by consideration of dinucleotide bias and codon pair bias manipulations and used in the synthesis of vaccines against various types of pathogenic bacteria and viruses. The idea of the future scope of genome recoding for developing virus-resistant plants and their challenges for the same are also comprehensively discussed. Although genome recoding is not yet tested on plants, however it could be very helpful in controlling plant viral diseases. So, it is a novel emerging area of research for developing viral resistant plants and thus would help in minimizing the agricultural losses in the near future.

     

Uterine and placental 5-HT profile in different gestational period of albino rats

Possible role of 5-HT in pregnancy was investigated in albino rats by biological estimation of uterine and placental 5-HT contents in different periods of gestation in normal and drug treated rats. Uterine 5-HT level increased steadily from day-1 of gestation to reach the peak on day-7; thereafter, the level continued to decline throughout the period till day-20 when 5-HT level was lowest. From day-20, a mild secondary rise started and remained persistent even after parturition. The results show that a critical level of 5-HT in early gestational period is necessary for conception. Manipulation of endogenous 5-HT do not influence duration of gestation.