Use of the Antiserum-Agar Plate Technique for Specific Identification and Isolation of Pasteurella pestis

Pasteurella pestis colonies were specifically identified on antiserum-agar plates used for primary culture of tissues from experimentally infected guinea pigs. Both selective and nonselective antiserum-agar plates were used to identify P. pestis from guinea pigs kept at 22 C for periods up to 4 days after death from plague. Colonies identified as P. pestis on selective and nonselective antiserum-agar plates, by the appearance of precipitin rings following brief chloroform vapor treatment, remained viable and were subsequently purified on nonselective antiserum-agar plates. Isolates obtained in this manner were uniformly lethal when injected into mice and guinea pigs, and conformed to standard laboratory criteria for P. pestis. P. pestis was identified on selective antiserum-agar plates from the spleens of all guinea pigs killed by the isolates, and from a large majority of the mice. The practical value and confirmative nature of the method were demonstrated.     

Vitamin E and selenium status of guinea pigs with myocardial necrosis

Myocardial necrosis and mineralization has been identified in a colony of guinea pigs which were subsequently tested for vitamin E and selenium deficiency. Serum vitamin E and whole blood selenium levels were within normal ranges. The erythrocyte glutathione peroxidase test has potential as a predictor of whole blood selenium levels in the guinea pig. The red blood cell hemolysis test used in this study did not correlate consistently with the serum vitamin E levels. We suspect that myocardial necrosis and mineralization may have resulted from inbreeding guinea pigs within the closed colony.     

禽分枝杆菌对豚鼠的致病性分析

【背景】我国禽型结核菌素(avian tuberculin)的制造用菌株为CVCC 68201、CVCC 68202和CVCC 68203株,但目前仍未明确这3株菌的生物学特性及对豚鼠致病性的情况。【目的】探究禽分枝杆菌(Mycobacterium avium)的生物学特性及对动物机体的致病性,为禽结核病和牛结核病的防控工作提供技术支撑。【方法】对3株禽分枝杆菌基因组进行鉴定分析及核酸相似度分析;用3株禽分枝杆菌分别感染豚鼠,观察感染后的临床症状、病理学变化、体重增重情况分析、皮内变态反应结果、脏器系数变化等,进而分析3株禽分枝杆菌对豚鼠的致病力。【结果】种型鉴定和进化分析结果表明,CVCC 68201、CVCC 68202和CVCC 68203均为禽分枝杆菌,基因组与Mycobacterium avium subsp. avium FDAARGOS_1608最为相近;在感染前期、中期、后期对3株禽分枝杆菌感染豚鼠的体重增重情况分析发现,感染禽分枝杆菌影响豚鼠增重,主要表现为生长迟缓,感染第5周时,CVCC 68201、CVCC 68202组豚鼠的平均体重明显轻于未感染组;皮内变态反应试验结果显示,感染CVCC 68201组豚鼠的皮肤红肿面积明显大于其他2个感染组,CVCC 68201可引起机体更为强烈的迟发型变态反应;3株禽分枝杆菌感染后,豚鼠脾脏和肺脏存在不同程度的肿大与出血,其中感染CVCC 68201豚鼠的肺脏系数与未感染组相比差异显著(P<0.01);病理学观察结果显示,豚鼠肺脏可见不同程度病变,其中CVCC 68201组更为严重,表现为肿大和轻微出血。各感染组豚鼠肺脏和脾脏组织切片抗酸染色均可见红色的分枝杆菌散在浸润。【结论】3株禽分枝杆菌对豚鼠均有一定程度的致病性,可引发局部病变。本研究为禽分枝杆菌的制备和鉴定提供依据,也为牛结核病的鉴别诊断方法研究提供参考。     

A new guinea pig mutant with abnormal hair production and immunodeficiency

Hairless guinea pigs were born in a closed colony of Hartley guinea pigs. At birth, hairless guinea pigs were smaller than littermates, had wrinkled skin and stunted vibrissae. The most striking abnormality histologically was distension of the upper portion of the pilary canal with thickening of the epidermis. Hairlessness resulted from production of abnormal hair shafts. Preliminary work indicated that in addition to hairlessness, the guinea pigs were athymic or hypothymic. Initial immunologic studies showed that the guinea pigs also were agammaglobulinemic. Animals that survived the weaning period died of infections that are usually associated with immunodeficiencies, such as systemic cytomegalovirus, systemic balantidiasis and Pneumocystis carinii pneumonia.     

Participation of capsaicin-sensitive neurons in the cardiovascular effects of neurotensin in guinea pigs

Intravenous (IV) infusions of neurotensin (NT) in anesthetized guinea pigs elicited dose-dependent pressor effects and tachycardia. Both effects were significantly reduced or abolished in guinea pigs given a chronic treatment with the neurotoxin capsaicin. In guinea pig isolated atria NT evoked a positive inotropic and chronotropic effect. Both effects were completely abolished in atria derived from capsaicin-treated guinea pigs. The positive inotropic and chronotropic effects of NT in guinea pig atria were mimicked by capsaicin and calcitonin gene-related peptide (CGRP). These results were interpreted as an indication that NT produces its cardiovascular effects in guinea pigs by activating capsaicin-sensitive sensory neurons.     

Comparison of the effects of estradiol-17beta and the synthetic estrogen, RU-2858, on lordosis behavior in adult female rats and guinea pigs

Female sexual behavior (as assessed by lordosis responses) in adult ovariectomized guinea pigs and rats was measured after a single subcutaneous injection of either the synthetic estrogen RU-2858 or estradiol-17β (E) and a subsequent injection of progesterone (P). Thresholds for responsiveness to each estrogen were determined over a range of doses from 1 to 640 μg/kg of body weight. RU-2858 was able to stimulate lordosis at doses several times lower than E in both guinea pigs and rats. In general, guinea pigs were less sensitive to both estrogenic compounds than rats and were particularly insensitive to E. Approximately 40% of guinea pigs given RU-2858 displayed lordosis prior to P injection. Subsequent P injection did not greatly enhance the intensity of lordosis responses in these animals. These guinea pigs were also more sensitive than the remaining 60% of RU-2858-injected guinea pigs on several indexes of lordosis intensity (e.g., lordosis threshold, duration of heat, duration of individual lordosis responses). Rats did not respond behaviorally to RU-2858 without a subsequent P injection nearly as frequently as did guinea pigs. At the doses used in this study, E did not facilitate lordosis behavior in rats or guinea pigs in the absence of a subsequent P injection.     

Comparison of in vitro platelet aggregation and its inhibition by three antithrombotic drugs between human and guinea pig

Platelets of guinea pigs are frequently used to evaluate the effect of new antiplatelet agents. Although several studies have compared the platelet aggregation between humans and guinea pigs, but so far the information is still limited. In this study, we compare the inhibitory effect of aspirin, dipyridamole and pentoxifylline on the platelet aggregation induced by adenosine diphosphate (ADP), collagen, arachidonic acid and thrombin between humans and guinea pigs. The results for humans and guinea pigs were compared and analysed by two-way analysis of variance (ANOVA). Our results showed: 1. The trends wherein these three drugs suppressed collagen-induced platelet aggregation was very similar in humans and guinea pigs. 2. In ADP-induced aggregation, the trend of inhibition caused by the three drugs was also similar in humans and guinea pigs except that a difference in platelet disaggregation at a late phase of platelet aggregation was noted. 3. In arachidonic acid- and thrombin-induced aggregations, the trend of inhibition caused by the three drugs was somewhat different in humans and guinea pigs. 4. Considering all activators as a whole, it was found that the status of platelet disaggregation at the late phase of platelet aggregation was different in humans and guinea pigs. Therefore, we concluded that: 1. Collagen was the most appropriate platelet activator when we used platelets of guinea pigs to study the effect of new antiplatelet agents. 2. When platelets of guinea pigs were used to study platelet aggregation, no matter which activator was used, we should avoid using the late phase of aggregation as the control index for comparison, because the results thus obtained might not be applicable to human platelets.     

Dose-Response Model for Lassa Virus

This article develops dose-response models for Lassa fever virus using data sets found in the open literature. Dose-response data were drawn from two studies in which guinea pigs were given subcutaneous and aerosol exposure to Lassa virus. In one study, six groups of inbred guinea pigs were inoculated subcutaneously with doses of Lassa virus and five groups of out-bred guinea pigs were similarly treated. We found that the out-bred subcutaneously exposed guinea pig did not exhibit a dose-dependent trend in response. The inbred guinea pigs data were best fit by an exponential dose-response model. In a second study, four groups of out-bred guinea pigs were exposed to doses of Lassa virus via the aerosol route. In that study, aerosol diameter was less than 4.5 μ m and both mortality and morbidity were used as endpoints. The log-probit dose-response model provided a somewhat better fit than the Beta-Poisson model for data with mortality as the endpoint, but the Beta-Poisson is considered the best fit model because it can be derived using biological considerations. Morbidity data were best fit with an exponential dose-response model.     

Immunogenicity of B-antigen in experimental plague and pseudotuberculosis

The results of the evaluation of the immunogenic properties of B-antigen, earlier identified in the culture fluid of Yersinia pseudotuberculosis submerged culture, with respect to experimental plague and pseudotuberculosis are presented. B-antigen has been shown to produce protective effect in guinea pigs and, probably, hamadryas baboons, but not in white mice infected with the causative agent of plague. Immunizaton with B-antigen protects guinea pigs from primary pneumonic plague caused by both capsule-forming and noncapsular Y. pestis virulent strains. Passive immunization with antibodies to B-antigen induces limitedly pronounced protective effect in guinea pigs and is not effective for white mice with respect to experimental plague. No active or passive protection of white mice or guinea pigs, infected with Y. pseudotuberculosis cultures, has been achieved by the injection of B-antigen or antibodies to it.     

Hairless pigmented guinea pigs: a new model for the study of mammalian pigmentation

A stock of hairless pigmented guinea pigs was developed to facilitate studies of mammalian pigmentation. This stock combines the convenience of a hairless animal with a pigmentary system that is similar to human skin. In both human and guinea pig skin, active melanocytes are located in the basal layer of the interfollicular epidermis. Hairless albino guinea pigs on an outbred Hartley background (CrI:IAF/HA(hr/hr)BR; designated hr/hr) were mated with red-haired guinea pigs (designated Hr/Hr). Red-haired heterozygotes from the F1 generation (Hr/hr) were then mated with each other or with hairless albino guinea pigs. The F2 generation included hairless pigmented guinea pigs that retained their interfollicular epidermal melanocytes and whose skin was red-brown in color. Following UV irradiation, there was an increase in cutaneous pigmentation as well as an increase in the number of active epidermal melanocytes. An additional strain of black hairless guinea pigs was developed using black Hr/Hr animals and a similar breeding scheme. These two strains should serve as useful models for studies of the mammalian pigment system.     

The daily pattern of heart rate, body temperature, locomotor activity, and autonomic nervous activity in congenitally bronchial-hypersensitive (BHS) and bronchial-hyposensitive (BHR) guinea pigs.

We studied the characteristics of the rhythmicity of heart rate (HR), body temperature (BT), locomotor activity (LA) and autonomic nervous activity in bronchial-hypersensitive (BHS) and bronchial-hyposensitive (BHR) guinea pigs. For this purpose, HR, BT, LA, and electrocardiogram (ECG) were recorded from conscious and unrestrained guinea pigs using a telemetry system. Autonomic nervous activity was analyzed by power spectral analysis of heart rate variability. Nocturnal patterns, in which the values in the dark phase (20:00-06:00) were higher than those in the light phase (06:00-20:00), were observed in HR, BT and LA in both strains of guinea pigs. The autonomic nervous activity in BHS guinea pigs showed a daily pattern, although BHR guinea pigs did not show such a rhythmicity. The high frequency (HF) power in BHS guinea pigs was higher than that in BHR guinea pigs throughout the day. Moreover, the low frequency/high frequency (LF/HF) ratio in BHS guinea pigs was lower than that in BHR guinea pigs throughout the day. These results suggest that parasympathetic nervous activity may be predominant in BHS guinea pigs.     

人附红细胞体感染FMMU白化豚鼠的研究

用附红细胞体分别感染FMMU白化豚鼠和普通花色豚鼠,同时测定两组豚鼠的红细胞免疫功能,探讨FMMU白化豚鼠的免疫学特性与病原体敏感性之间的关系。结果表明,FMMU白化豚鼠对人附红细胞体比普通花色豚鼠敏感。封闭群FMMU白化豚鼠有独特的免疫学特性,红细胞免疫功能低于普通花色豚鼠,对病原体敏感性高于普通花色豚鼠,更适于建立感染性疾病动物模型。     

Experimental Haemonchus contortus infections in guinea pigs

Approximately 40% of exsheathed Haemonchus contortus larvae administered to guinea pigs established in the stomach and developed into fourth stage larvae. Most worms were then lost between 5 and 7 days after infection and the guinea pigs were resistant to a second infection. Haemorrhage, oedema and infiltration with inflammatory cells, especially eosinophils, developed in the stomach wall of infected guinea pigs and reactive hyperplastic changes occurred in the gastric lymph node. H. contortus infection of guinea pigs has some potential as a model for study of the pathology, immunology and chemotherapy of gastric nematodiasis.     

Transmission of rat and guineapig Haemophilus spp. to mice and rats

Mice and rats, free from Pasteurellaceae, were exposed to Haemophilus spp. (V-factor dependent Pasteurellaceae) by housing in proximity to infected rats or guinea pigs, and monitored by culture and enzyme-linked immunosorbent assay (ELISA) for cross infection. A minority of mice became infected when exposed to Haemophilus-infected rats but none when exposed to guinea pigs. Rats were readily infected when exposed to Haemophilus-infected guinea pigs or rats. Although Pasteurellaceae infections are commonly considered as host specific, our data show that Haemophilus spp. can cross the species barrier from rats to mice and from guinea pigs to rats.     

Enhanced multiplication and transmission of Streptococcus pneumoniae in guinea pigs by Sendai virus infection

It was demonstrated that the transmission S. pneumoniae in guinea pigs was remarkably promoted by the combined infection with Sendai virus in the following experiments. When guinea pigs infected with S. pneumoniae alone (infector) were cagemated with non-treated guinea pigs (contact) for 2 and 4 weeks, only 2 of 30 contacts were infected with the organism. On the contrary, when the contact guinea pigs were infected with Sendai virus and immediately cage-mated with the infectors, the pneumococcal infection occurred in 25 of 30 contacts during 2 to 4 weeks period. In the experiment in which 30 non-treated contacts were cage-mated with pneumococcal infectors for 4 weeks and then infected with Sendai virus, no pneumococcal infection was demonstrated in the contacts, suggesting no presence of latent infection of the organism in the contact guinea pigs. Twenty-five of 30 contacts suffered from pneumococcal infection when they were exposed to Sendai virus for 2 weeks and then cage-mated with infectors. The multiplication of S. pneumoniae in the respiratory tract of the guinea pigs was remarkably enhanced by combined infection with Sendai virus. Namely, a 1000-fold increase in the number of organism resulted in the guinea pigs suffered from combined infection as compared with that in the animals received pneumococcal single infection.     

Biochemical basis for the resistance of guinea pigs to carcinogenesis by 2-acetylaminofluorene

Studies were made on why guinea pigs are resistant to carcinogenesis by 2-acetylaminofluorene. Cytochrome P-448 and arylhydrocarbon hydroxylase were not induced in either the microsomes and nuclei of guinea pigs by 3-methylcholanthrene treatment. 3-Methylcholanthrene treatment caused only 2-fold increase in the binding of 2-acetylaminofluorene to DNA in nuclei isolated from guinea pigs, while it caused 17-fold increase in the binding in rat nuclei. Microsomes from 3-methylcholanthrene treated rats had 5 times more effect than Microsomes from 3-methylcholanthrene treated guinea pigs on the binding of 2-acetylaminofluorene to DNA of nuclei from untreated guinea pigs. N-Hydroxy-2-acetylaminofluorene combined equally well with the DNA of rats and guinea pigs. In guinea pigs, there was a good correlation between the low inducibility of cytochrome P-448 and the low binding of 2-acetylaminofluorene to DNA. Our results clearly showed that guinea pigs are resistant to tumor induction by 2-acetylaminofluorene through inability to carry out the first step of activation of 2-acetylaminofluorene.     

An outbreak of Trixacarus caviae infestation in guinea pigs at an animal petting facility and an evaluation of the safety and suitable dose of selamectin treatment

In June 2009, 27 guinea pigs kept at an animal petting facility at a zoo in Kanagawa Prefecture, Japan, were observed to scratch intensely, weaken, and develop lesions. Three sarcoptiform mites were found in skin scrapings taken from affected areas of 2 guinea pigs, and they were identified as Trixacarus caviae by morphological examination. This result confirmed the presence of T. caviae in Japan. For treatment, doses of 13.6-18.75 mg/head of selamectin were administered in a topical preparation applied to a single spot on the skin on the back of the neck, and no side effects were observed. In April 2010, a second outbreak of mange occurred at the zoo, and, following investigation, 2 mite eggs were observed. It was, therefore, thought probable that the mites had survived during the winter within nonclinical carriers. Accordingly, doses of 5.0-7.5 mg/head of selamectin were applied on days 0 and 28, after which clinical symptoms disappeared and general condition improved. This dose of selamectin was thus shown to be a suitable and economical treatment for guinea pigs infested with the mites. Because the mite is not always easily observed in infested guinea pigs and the potential for human infestation exists, clinicians should not hesitate to treat when the clinical presentation suggests infestation, particularly in a setting such as an animal petting facility, where large numbers of children and adults have direct contact with the animals.     

花色豚鼠与白化豚鼠静脉血电解质、酸碱平衡及血气的比较学研究

目的比较研究花色豚鼠与白化豚鼠静脉血电解质、酸碱平衡及血气情况。方法分别取健康成年花色豚鼠和白化豚鼠,利用便携式多功能麻醉机经异氟烷吸入麻醉后,腹主静脉取血,经NOVA血气．电解质分析仪全自动分析测定电解质、酸碱平衡及血气等指标。结果花色豚鼠的Cl-、pH、SBC、PO2、SV O2、O2ct均显著低于白化豚鼠（P〈0．05,P〈0．01）,而PCO2显著高于白化豚鼠（P〈O．05）。结论花色豚鼠的携氧能力明显低于白化豚鼠,可以作为血瘀证和亚健康模型研究较好的实验动物。     

Characterization of a novel parainfluenza virus,caviid parainfluenza virus 3, from laboratory guinea pigs (Cavia porcellus)

A novel Respirovirus was isolated from nasopharyngeal swab specimens from clinically normal laboratory guinea pigs, and was characterized and named caviid parainfluenza virus 3 (CavPIV-3). The CavPIV-3 is enveloped, is 100 to 300 nm in diameter, and has a characteristic 15-nm-diameter chevron-shaped virus ribonucleocapsid protein. Sequence analysis of the fusion glycoprotein of CavPIV-3 revealed it to be 94% identical to human and guinea pig parainfluenza 3 (PIV-3) viruses and 80% identical to bovine PIV-3. To determine whether CavPIV-3 causes clinical disease in laboratory guinea pigs and to compare the serologic response of guinea pigs to CavPIV-3 and to other paramyxoviruses, an infection study was performed, in which groups of guinea pigs were inoculated with CavPIV-3, Sendai virus, simian virus 5 (SV-5), murine pneumonia virus (PVM), or bovine PIV-3 virus. During the course of the study, guinea pigs were maintained in an infectious disease suite, housed in Micro-Isolator cages, and were only manipulated under a laminar flow hood. Clinical signs of disease were not observed in any of the paramyxovirus-inoculated guinea pigs during the eight-week course of the study, and histologic signs of disease were not evident at necropsy eight weeks after inoculation. Guinea pigs inoculated with CavPIV-3, Sendai virus, PVM, and bovine PIV-3 developed robust homologous or heterologous serologic responses. In contrast, guinea pigs inoculated with SV-5 developed modest or equivocal serologic responses, as assessed by use of an enzyme-linked immunosorbent assay. Further, use of the SV-5 enzyme-linked immunosorbent assay resulted in the highest degree of non-specific reactivity among all of the paramyxovirus assays. In summary, CavPIV-3 is a novel guinea pig Respirovirus that subclinically infects laboratory guinea pigs, resulting in a robust serologic response, but no observed clinical or histologic disease. The CavPIV-3 fusion glycoprotein gene sequence is available from GenBank as accession No. AF394241, and the CavPIV-3 virus is available from the American Type Culture Collection as accession No. DR-1547.     

Effect in neonatal thymectomy on experimental autoimmune thyroiditis in guinea pigs.

These studies examined the effect of neonatal thymectomy on the induction of experimental autoimmune thyroiditis (EAT) in the guinea pigs. Thymectomy was found to result in a consistent and profound inhibition of the development of lesions of EAT in both strain 2 and strain 13 guinea pigs. Thymectomized guinea pigs also had reduced antibody titers to guinea pig thyroglobulin (GPTG), while delayed hypersensitivity reactions to GPTG were less markedly affected by thymectomy. Thymectomized guinea pigs had significant functional peripheral T cells as evidenced by normal responses of lymph node cells to T cell mitogens. These results indicate that a T cell subpopulation which is sensitive to neonatal thymectomy is required for the development of EAT and antithyroglobulin antibody in the guinea pig.