Susceptibility of several strains of mice to Echinostoma hortense infection

Susceptibilities of 5 different mice strains, including C3H/HeN, BALB/c, C57BL6, FvB and ICR, to Echinostoma hortense infection, was evaluated. The worm expulsion rate, worm size and egg production were observed from 1 to 8 weeks after infection with 30 metacercariae. C3H/HeN and ICR mice showed the highest worm maturation rates. The worm recovery rate and the number of eggs per gram (EPG) of feces was also higher in C3H/HeN and ICR mice than in BALB/c, C57BL6, and FvB mice. It is suggested that E. hortense is highly infectious to ICR and C3H/HeN mice, but not to the other strains of mice. Based on the results obtained, we believe that the susceptibility of different mouse strains to E. hortense infection is dependent on the genetic and immunologic background of mice.     

Susceptibility of inbred mouse strains to infection with three species of Metagonimus prevalent in the Republic of Korea

Susceptibility of inbred mouse strains to Metagonimus yokogawai, Metagonimus miyatai, and Metagonimus takahashii infections was studied using BALB/c, ddY, C57BL/6J, C3H/HeN, and A/J mice, with H-2 haplotypes d, s, b, k, and a, respectively. Two hundred metacercariae were orally fed to each mouse, and the worm recovery rates (WRR), worm dimensions, and intrauterine egg numbers were measured at days 3, 7, 14, 21, and 28 postinfection (PI). On day 14 PI, the WRR of M. yokogawai was highest in ddY mice (average, 62.2%); those of M. miyatai and M. takahashii were highest in ddY (19.5%) and BALB/c mice (10.4%), respectively; worm maturation was best in C3H/HeN (M. yokogawai), C57BL/6J (M. miyatai), and ddY mice (M. takahashii). All mouse strains showed higher susceptibility to infection with M. yokogawai than with M. miyatai or M. takahashii. The results show that susceptibility of mice to Metagonimus infection varies according to mouse strain and parasite species but is suggested to be independent of the mouse H-2 haplotype.     

Susceptibility of inbred mice to Leishmania tropica infection: correlation of susceptibility with in vitro defective macrophage microbicidal activities

Eleven mouse strains were inoculated in footpads with amastigotes of Leishmania tropica and observed for 12 weeks. Liver and spleen impression smears from infected mice were examined for the presence of intracellular parasites. Four strains (BALB/cJ, C57L/J, NZW/N, and P/J) failed to heal the subcutaneous lesion and showed evidence of systemic infection; the remaining seven strains (A/J, C3H/HeJ, C3H/HeN, C3HeB/FeJ, C57BL/6J, C57BL/10J, and C57BL/10ScN) were each resistant to infection and resolved their lesions by Week 10. Macrophages from the four susceptible strains could not be activated to kill L. tropica amastigotes by treatment with soluble lymphocyte products in vitro. In contrast, macrophages from all seven resistant strains responded to lymphokine treatment and eliminated 80-90% of intracellular parasites. These results suggest that in vitro macrophage microbicidal activities predict the course of systemic leishmanial disease.     

Differences in antibody production against mouse hepatitis virus (MHV) among mouse strains

Several strains of mice were examined for antibody production after intranasal inoculation with a low virulence strain of mouse hepatitis virus (MHV), MHV-NuU. C57BL/6N mice were shown to be high responders in the production of complement fixing (CF) antibody as compared to C3H/HeN, BALB/c-AnN, DBA/2N mice. F1 hybrids B6C3 and BDF1 from C57BL/6N mice, showed CF antibody responses as high as C57BL/6N, suggesting that high responsiveness is genetically controlled. All these mouse strains were able to produce high titred neutralizing antibody to MHV.     

Participation of embryonic genotype in the pregnancy block phenomenon in mice.

Pregnancy block by male pheromones in mice differs in incidence depending on the combination of strains. Female mice of BALB/cA strain mated with BALB/cA males show a 100% pregnancy block when exposed to males of inbred strain DDK shortly after copulation (Chung et al., Biol Reprod 1997; 57:312-319). In the present study, BALB/cA females mated with the males of other strains--CBA/J, C3H/HeN, C57BL/6Cr, and IXBL--showed higher pregnancy rates (66.6-87. 5%) even when they were exposed to DDK males. In the pharmacological induction of pregnancy block with dopamine agonist (bromocriptine, 4 mg/kg BW), BALB/cA females mated with BALB/cA males showed a 100% pregnancy block. In contrast, BALB/cA females mated with CBA/J, C3H/HeN, and C57BL/6Cr males showed higher pregnancy rates (40-70%). These results suggest that the better pregnancy rate of BALB/cA females mated with alien males may be due to the stronger viability of F(1) embryos. This interpretation was confirmed by an embryo transfer experiment in which a higher implantation rate was observed when BALB/cA embryos grown in BALB/cA females exposed to BALB/cA males were transferred into recipient BALB/cA females exposed to DDK males. These results suggest that the embryonic genotype or viability of the embryo is one factor contributing to the occurrence of pregnancy block by male pheromones in mice.     

Basal lung mechanics and airway and pulmonary vascular responsiveness in different inbred mouse strains.

Little is known about interstrain variations in baseline lung functions or smooth muscle contractility in murine lungs. We therefore examined basal lung mechanics and airway, as well as vascular reactivity to methacholine, thromboxane (using U-46619), and endothelin-1 (ET-1), A/J, AKR, BALB/c, C3H/HeN, C57BL/6, and SCID mice. All experiments were performed with isolated perfused mouse lungs. Except AKR mice (which were excluded from further analysis), all other strains showed stable pulmonary compliance, pulmonary resistance, and pulmonary arterial pressure within a control period of 45 min. Among these strains, C3H/HeN mice exhibited higher dynamic pulmonary compliance and lower pulmonary resistance, whereas SCID mice had higher baseline pulmonary resistance than the other strains. Concentration-response experiments with methacholine showed a lower airway reactivity for C57BL/6 mice compared with the other strains. Perfusion with 1 microM U-46619 or 100 nM ET-1 revealed a similar pattern: the agonist-inducible broncho- and vasoconstriction was lower in C57BL/6 mice than in all other strains, whereas it tended to be higher in SCID mice. The present study demonstrates a correlation between airway and vascular responsiveness in all tested strains. SCID mice are hyperreactive, whereas C57BL/6 mice are hyporeactive, to smooth muscle constrictors. Lung mechanics, as well as airway and vascular responsiveness, appear to be genetically controlled.     

Sensitivity difference to the suppressive effect of prostaglandin E2 among mouse strains: a possible mechanism to polarize Th2 type response in BALB/c mice

PGE2 has been shown to play a prominent role in regulating Th1 and Th2 type responses. We studied the role of PGE2 in IFN-gamma production by Staphylococcus aureus Cowan I-stimulated spleen cells from several mouse strains such as BALB/c, C3H/HeN, and C57BL/6. When spleen cells were pretreated with indomethacin (cyclooxygenase (COX)-1 and COX-2 inhibitor) or NS-398 (COX-2-specific inhibitor), S. aureus Cowan I -induced IFN-gamma production was increased more markedly in spleen cells from BALB/c mice than from C3H/HeN and C57BL/6 mouse. However, PGE2 production was not significantly different among spleen cells from three mouse strains. When various concentrations of PGE2 were exogeneously added to spleen cells, PGE2 showed a stronger suppressive effect on IFN-gamma production in spleen cells from BALB/c mice than from other strains of mice. This suppressive effect of PGE2 in BALB/c mice mainly depended on IL-12p70 production by APCs. More PGE2 binding sites were found in BALB/c spleen cells than in C3H/HeN spleen cells, indicating that the sensitivity difference to the suppressive effect of PGE2 was due to the difference of the number of PGE2 receptors. The administration of NS-398 into BALB/c mice enhanced Ag-specific IFN-gamma production, but not IL-4 production. This effect is the same as IL-12 administration in vivo. From these results, we propose that the modulation of PGE2 is important for Th1 activation via IFN-gamma and IL-12p70 production in vitro and in vivo and that PGE2 is one of the pivotal factors in the Th2-dominant immune response in BALB/c mice.     

Strain variation in the susceptibility and immune response to Clonorchis sinensis infection in mice

Mice have shown various susceptibility to infection by Clonorchis sinensis. To compare the intra-specific variation in the host-parasite relationship of C. sinensis, 6 strains of mice (ICR, BALB/c, C57BL/6, DDY, CBA/N, and C3H/HeN) with 3 different haplotypes were evaluated on their susceptibility. The worm recovery rate and immunological responses were observed after 4 and 8 weeks of infection with 30 metacercariae. The highest worm recovery rate was observed as 20.7% in the C3H/HeN strain after 4 weeks of infection along with histopathological changes. The rate was 10.0% in C57BL/6 mice after 8 weeks. ICR, BALB/c, and CBA/N showed elevated levels of IgE at both time points when compared to the rest of the strains. The serum IgG1 and IgG2a levels were elevated in most of the strains; however, the C57BL/6 strain showed a lower level of IgG2a that indicated the IgG1 predominance over IgG2a. The production of IL-4 after concanavalin-A stimulation of splenocytes slightly increased among the mouse strains except C3H/HeN after 4 or 8 weeks of infection, but each strain produced high levels of IFN-γ after 8 weeks, which implied mixed Th1/Th2 responses. ICR, DDY, CBA/N, and C3H/HeN strains showed a significantly increased level of IL-10 after 8 weeks as compared to C57BL/6. All of the strains showed an increased level of IL-13 and suggested fibrotic changes in the mice. In conclusion, mice are insusceptible to infection with C. sinensis; however, the C57BL/6, BALB/c and ICR strains are relatively susceptible after 8 weeks of infection among the six strains. Worm expulsion may be one of the causes of low susceptibility of C3H/HeN mice strain at the 8th week. Elevated IgE, IFN-γ, and IL-13 of infected mice suggest both Th1 and Th2 responses that may be related to the low host susceptibility.     

Role of intestinal goblet cells in the expulsion of Gymnophalloides seoi from mice

Role of intestinal goblet cells (GCs) in the expulsion of Gymnophalloides seoi was studied using 4 strains of mice, ICR, C3H/ HeN, BALB/c, and C57BL/6, after infection with 200 metacercariae isolated from oysters. On day 7 postinfection (PI), significantly higher (P < 0.05) worm recovery rates (WRRs) were observed in ICR (29.5 +/- 12.0%) and C3H/HeN (14.8 +/- 8.2%) than in BALB/c (5.7 +/- 5.3%) and C57BL/6 (0.8 +/- 1.1%) mice. Alteration of the GC mucins was marked in C57BL/6 mice. On day 14 PI, 5.2 +/- 5.2% and 0.6 +/- 0.7% of worms were recovered only from ICR and C3H/HeN mice. When C57BL/6 mice were immunosuppressed with prednisolone, WRR on day 7 PI increased to 11.7 +/- 13.9%, whereas the GC hyperplasia and mucin alteration diminished significantly. The results suggest that expulsion of G. seoi from the intestine is dependent on immune responses of the host, and GCs may be an important effector.     

Sex and strain differences of mouse variant salivary proteins

Proteins of the mouse saliva are resolved into about 20 discrete bands by polyacrylamide gel electrophoresis. Sexual dimorphism and monomorphism were found in a subset (Msp-1) of these salivary proteins from different inbred strains. This sexual dimorphism involves a fast moving band (F-type) and a slow moving one (S-type). Mature males of seven strains (A/J, AKR, CBA/J, C3H/HeN, A/Sn, B10.A, and B10.BR) exhibit the S phenotype while mature females of these strains were typed as F. Sexually immature males and females of these strains were uniformly typed as F, but at puberty (5-6 weeks of age) the phenotype of the males switched to type S, while the phenotype of the females remained the same. This switch to type S at puberty did not take place in males of four strains (BALB/cAnn, B10.D2, C57BL/6, and C57BL/10); therefore, we conclude that these strains were sexually monomorphic with regard to Msp-1. The phenotype of mature males of C3H/HeN reverted to type F following castration, whereas castrated males and mature females switched to type S in response to testosterone administration. The testosterone treatment had no effect on the type S phenotype of males and females of the sexually monomorphic BALB/cAnn strain. The male-specific type S phenotype of Msp-1 was seen only in mice with H-2 haplotype a or k; thus an association with H-2 haplotype was suggested. All F1 males of reciprocal crosses involving the sexually dimorphic and monomorphic strains (e.g., C3H/HeN X BALB/cAnn) demonstrated the type S phenotype at puberty.     

Varying susceptibility of pulmonary cytokine production to lipopolysaccharide in mice

Objectives: The lipopolysaccharide (LPS)-induced acute lung injury (ALI) model has been widely applied for pathophysiological and pharmacological research. The aim of present study is to understand the variation of acute pulmonary inflammation between mouse strains. Methods: The present study investigated the susceptibility of acute production of inflammatory mediators, e.g. cytokines, chemokines and others, to LPS in C57BL/6J, Balb/cJ, DBA/1J, CD-1, NMRI, DBA/2J, A/J, and C3H/HeN mice. Results: The susceptibility to intra-tracheal challenge with LPS varied between measured variables, durations and strains. General lung hyper-reactive susceptibility to LPS-induced pulmonary production of 6–8 inflammatory mediators followed the order NMRI, Balb/cJ, C3H/HeN, A/J, C57BL/6J, DBA/1J, DBA/2J and CD-1 mice at 4 h, and A/J, C3H/HeN, CD-1, NMRI, C57BL/6J, Balb/cJ, DBA/2J and DBA/1J mice at 24 h. Conclusions: Our data provide information for scientists to consider the proper strain of mice for the measurement of specific inflammatory mediators and to select sensitive or resistant mouse strains for understanding genetic variation in the pathogenesis and for the screening of target-oriented drug development.     

Effect of genotype on the efficiency of mouse embryo cryopreservation by vitrification or slow freezing methods

We examined possible genotype effects on the survival of 8- to 16-cell mouse embryos isolated from four inbred strains (C57BL/6N, BALB/cAnN, DBA/2N, and C3H/HeN), a outbred stock (ICR), and various crosses after cryopreservation by vitrification or conventional slow freezing using glycerol solutions. The rates of in vitro development of C57BL/6N, BALB/cAnN, C3H/HeN, and ICR embryos to expanded blastocysts ranged from 86% to 94% after slow freezing and 85% to 97% after vitrification. The cryopreservation method did not significantly influence in vitro embryo survival after thawing (P >0.05). Although genotype significantly influenced the in vitro survival of embryos (P = 0.008), this presumably resulted from an increased difficulty in assessing the quality grade of C3H/HeN embryos prior to cryopreservation. The rates in vivo development of C57BL/6N, BALB/cAnN, C3H/HeN, DBA/2N, and ICR embryos to normal day 18–19 fetuses ranged from 19% to 64% after slow freezing and from 18% to 63% after vitrification. The in vivo development of cryopreserved embryos was significantly influenced by cryopreservation method and genotype (P = 0.01 and P = 0.001, respectively). Vitrification yielded significantly higher rates of in vivo development than that after slow freezing (P > 0.05). In vivo development rates of DBA/2N and ICR♀ X B6D2F1 ♂ embryos after cryopreservation were significantly higher than that of embryos from BALB/cAnN and C3H/HeN mice (P < 0.05). These results indicate that parental genotype exerts little or no effect on the ability of embryos to develop in vitro after vitrification or slow freezing. Differences in the ability of cryopreserved embryos to develop normally in vivo may reflect inherent genotype related differences in their post-implantation developmental potential and not their sensitivity to cryoinjury. © 1995 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Reduced expression of STAT4 and IFN-gamma in macrophages from BALB/c mice

BALB/c mice have been shown to easily induce Th2 type responses in several infection models. In this study, to examine the mechanisms of Th2 dominant responses in BALB/c mice, we assessed several macrophage functions using C3H/HeN, C57BL/6, and BALB/c mouse strains. Peritoneal macrophages from three strains of mice equally produced IL-12 by stimulation with LPS plus IFN-gamma. However, IFN-gamma production in response to IL-12 or IL-12 plus IL-18 was much lower in macrophages from BALB/c mice than other strains. IFN-gamma produced by activated macrophages induced IL-12R mRNA expression in T cells and macrophages themselves depending on their amount of IFN-gamma; namely, macrophages from BALB/c mice induced lower expression of IL-12R. Intracellular levels of STAT4 were much lower in macrophages from BALB/c mice. However, other STATs, such as STAT1 or STAT6, were expressed similarly in the three mouse strains. STAT4 and IFN-gamma production by other cell types such as T cells and B cells were equal in C3H/HeN and BALB/c mice. These results indicate that macrophages from Th2-dominant BALB/c mice have different functional characters compared with other mouse strains; that is, STAT4 expression and IFN-gamma production are reduced, which is one of the causes to shift to Th2-type responses.     

Sex and strain differences of mouse variant salivary proteins

Abstract. Proteins of the mouse saliva are resolved into about 20 discrete bands by polyacrylamide gel electrophoresis. Sexual dimorphism and monomorphism were found in a subset (Msp-1) of these salivary proteins from different inbred strains. This sexual dimorphism involves a fast moving band (F-type) and a slow moving one (S-type). Mature males of seven strains (A/J, AKR, CBA/J, C3H/HeN, A/Sn, B10.A, and B10.BR) exhibit the S phenotype while mature females of these strains were typed as F. Sexually immature males and females of these strains were uniformly typed as F, but at puberty (5–6 weeks of age) the phenotype of the males switched to types, while the phenotype of the females remained the same. This switch to type S at puberty did not take place in males of four strains (BALB/cAnn, B10.D2, C57BL/6, and C57BL/10); therefore, we conclude that these strains were sexually monomorphic with regard to Msp-1. The phenotype of mature males of C3H/HeN reverted to type F following castration, whereas castrated males and mature females switched to type S in response to testosterone administration. The testosterone treatment had no effect on the type S phenotype of males and females of the sexually monomorphic BALB/cAnn strain. The male-specific type S phenotype of Msp-1 was seen only in mice with H-2 haplotype a or k; thus an association with H-2 haplotype was suggested. All F₁ males of reciprocal crosses involving the sexually dimorphic and monomorphic strains (e.g., C3H/HeN × BALB/cAnn) demonstrated the type S phenotype at puberty.     

Effect of Mouse Strain in a Model of Chemical-induced Respiratory Allergy

The inhalation of many types of chemicals is a leading cause of allergic respiratory diseases, and effective protocols are needed for the detection of environmental chemical–related respiratory allergies. In our previous studies, we developed a method for detecting environmental chemical–related respiratory allergens by using a long-term sensitization–challenge protocol involving BALB/c mice. In the current study, we sought to improve our model by characterizing strain-associated differences in respiratory allergic reactions to the well-known chemical respiratory allergen glutaraldehyde (GA). According to our protocol, BALB/c, NC/Nga, C3H/HeN, C57BL/6N, and CBA/J mice were sensitized dermally with GA for 3 weeks and then challenged with intratracheal or inhaled GA at 2 weeks after the last sensitization. The day after the final challenge, all mice were euthanized, and total serum IgE levels were assayed. In addition, immunocyte counts, cytokine production, and chemokine levels in the hilar lymph nodes (LNs) and bronchoalveolar lavage fluids (BALF) were also assessed. In conclusion, BALB/c and NC/Nga mice demonstrated markedly increased IgE reactions. Inflammatory cell counts in BALF were increased in the treated groups of all strains, especially BALB/c, NC/Nga, and CBA/J strains. Cytokine levels in LNs were increased in all treated groups except for C3H/HeN and were particularly high in BALB/c and NC/Nga mice. According to our results, we suggest that BALB/c and NC/Nga are highly susceptible to respiratory allergic responses and therefore are good candidates for use in our model for detecting environmental chemical respiratory allergens.     

Trypanosoma cruzi: infection patterns in intact and athymic mice of susceptible and resistant genotypes

Inbred strains of mice inoculated with the T cruzi Y strain behaved as susceptible (A/J, C3H/HeN), intermediate (BALB/c) or relatively resistant (C57BL/6) with respect to the magnitude of parasitaemia and mortality rate. C57BL/10 mice were susceptible in relation to parasitaemia but resistant when mortality was analyzed. Infection with T cruzi CL strain presented the same results, except for C57BL/6 which behaved as susceptible mice. Athymic mice of various backgrounds revealed no differences in susceptibility, presenting the same dramatic parasitaemia, tissue colonization pattern and no inflammatory reaction in any of the tissues studied. Infection of euthymic and athymic BALB/c mice elicited the production of parasite-specific antibodies, which reached similar levels on the first 9 days but differed after day 13. Serum transfer experiments in BALB/c mice did not show great differences in parasitaemia but altered T. cruzi polymorphism reducing the slender forms in athymic mice. Histopathology of athymic BALB/c mice showed the same tissue tropism when infected either with T cruzi Y or CL strain.     

Retention of a memory trace of learning induced by a new and extinctive stimulus in C57BL/6J and BALB/c mice

Influence of preliminary habituation to the experimental box on passive avoidance learning was studied in mice of C57BL/6J and BALB/c strains. The 20-fold preexposure of mice to the environmental stimulus inhibited the acquisition and consequent retention of a memory trace in BALB/c mice and did not affect the acquisition in C57BL/6J mice. Subsequent retention in this strain was facilitated. The interstrain differences are discussed with respect to detected genetically determined types of behavior and exstinctive inhibition at the habituation stage.     

Improved in vitro fertilization and development by use of modified human tubal fluid and applicability of pronucleate embryos for cryopreservation by rapid freezing in inbred mice

We examined in vitro fertilizability and development of 10 inbred mouse strains (C57BL/6J, C57BL/10, C57BL/10.D2/newSn, C57BL/10-Thy1.1, C57BL/10.Br/Sn, C3H/He, RFM/Ms, STS/A, BALB/c-nu and C.B-17/Icr), and the viability of frozen-thawed in vitro fertilized (IVF) embryos after embryo transfer (ET). In seven strains, fertilizability was significantly greater in modified human tubal fluid (mHTF) compared with modified Krebs-Ringer's bicarbonate solution (TYH medium). The TYH medium supported almost no fertilization in four strains. More than 80% of IVF embryos developed to the blastocyst stage by 120 h in potassium-enhanced simplex optimization medium (KSOM). Reciprocal fertilization between C57BL/6J and BALB/c-nu gametes in TYH medium yielded poor fertilization o f BALB/c-nu due to spermatozoal deficiencies. Increased concentrations of bovine serum albumin and spermatozoa during capacitation and Percoll washing did not drastically affect fertilization. The mHTF, but not TYH medium, supported BALB/c-nu spermatozoa penetration into the zona pellucida irrespective of capacitation media. In vitro fertilized embryos frozen-thawed rapidly were transferred to surrogate mothers at the two-cell stage. Compared with that of unfrozen controls, rapid freezing had no significant effect on fetus development except in C57BL/10.D2/newSn mice. These results suggest that mHTF medium is superior with respect to IVF of inbred mice, and that KSOM adequately supports in vitro fertilized embryo development in inbred mice. The data also indicate that rapid freezing of pronucleate embryos following IVF is suitable for cryopreservation and embryo banking of inbred mice and for the production of genetically modified mice.     

Strain difference in mouse natural killer activity augmented by mouse interferon and poly I.C

The level of natural killer (NK) activity was found to vary considerably among several mouse strains. In vivo and in vitro, interferon (IFN) and IFN inducers have been shown to augment mouse NK activity. C3H/He mice showed high NK activity, DDD/1 and A/J mice low NK activity, and C57BL/6, BALB/c and DBA/2 mice intermediate NK activity after injection with polyinosinic polycytidylic acid (poly I. C.). The same NK activity correlation was observed in nontreated mice, but the NK activities were lower compared with the poly I. C.-injected mice. Moreover, the DDD/1 and A/J mice showed almost no augmentation of NK activity on injection with poly I.C. In vivo, C3H/He, BALB/c and C57BL/6 mice injected with IFN showed augmented NK activity, but DDD/1 mice showed no such reaction. In vitro, C3H/He, BALB/c and C57BL/6 mouse spleen cells treated with IFN also showed augmented NK activity, but DDD/1 mouse spleen cells showed almost none. F1 hybrids between high (C3H/He) and low (DDD/1) NK-activity strains showed high NK activity. Thus, activity is dominant over low activity. The segregation of (DDD/1 X C3H/He) Fl X DDD/1 back-cross mice suggested that the strain differences in NK activity are under polygenic control.     

甲型H1N1流感病毒感染不同免疫缺陷小鼠的比较

目的宿主免疫系统的功能状态在病毒的感染中起着至关重要的作用,本实验观察了不同免疫缺陷小鼠感染甲型H1N1流感病毒的差异。方法使用六个品系的近交系小鼠,经乙醚麻醉后进行滴鼻攻毒,分析其在病毒感染后存活率、体重变化和肺组织病理改变的异同。结果感染H1N1病毒的6种小鼠在观察的14d内,野生型的C57BL／6小鼠感染开始体重缓慢下降,感染后期有所回升,有半数存活;BALB／c小鼠和四种免疫缺陷品系小鼠感染病毒后体重随病情发展快速下降,死亡率均为100％。野生型C57BL／6小鼠感染初期为较弥漫的间质性肺炎,后期病变逐渐局限;BALB／c小鼠和四种免疫缺陷品系小鼠感染病毒后出现弥漫的中重度间质性肺炎,细支气管上皮有变性坏死,但炎症细胞明显少于C57BL／6小鼠。结论在甲型H1N1流感病毒的初次感染中固有免疫和特异性免疫分别在感染的初期和后期起主要作用,宿主免疫系统的功能状态影响着甲型H1N1病毒感染和预后。