Molecular cloning and expression of gerbil granulocyte/macrophage colony-stimulating factor

Experimental infection of Z:ZCLA Mongolian gerbils with human hepatitis E virus

AIM: To investigate whether Z:ZCLA Mongolian gerbils are readily susceptible to infection by human hepatitis E virus (HEV).

METHODS: Z:ZCLA Mongolian gerbils were infected with a clinical HEV strain isolated from an acute hepatitis E patient, and virus pathogenesis was assessed in this host. Non-infected gerbils served as the control group. Feces samples from gerbils were collected weekly for reverse transcription-nested polymerase chain reaction. Serum anti-HEV IgG and alanine aminotransferase (ALT) were detected by enzyme linked immunosorbent assay. At sacrifice, each animal’s liver, spleen and kidney were collected for histopathologic examination.

RESULTS: HEV-infected gerbils showed fatigue, with histopathological changes observed in the liver, spleen and kidney. HEV RNA was detected in fecal samples taken at day 7 after inoculation and the detectable levels lasted out to day 42 after inoculation. Interestingly, ALT levels were only moderately increased in the HEV-infected animals compared with the non-infected control group.

CONCLUSION: Z:ZCLA Mongolian gerbils are susceptible to human HEV.

Sequence determination of the heavy-chain constant region in four immunoglobulin classes of Mongolian gerbils (Meriones unguiculatus)

We determined partial cDNA sequences of four immunoglobulin (Ig) classes-IgM, IgG1, IgE, and IgA-of Mongolian gerbil (Meriones unguiculatus). Each deduced Ig heavy-chain constant (IGHC) region-Cµ, Cγ1, Cε, and Cα-is structurally similar to its counterparts in the mouse and rat, and phylogenetic analysis suggests that the gerbil Igs are evolutionarily close to their counterparts. In spite of the high sequence homology to the other rodent Cγ sequences, the gerbil Cγ1 sequence differs from our previously reported Cγ2. This result indicates that the gerbil has at least two IgG subclasses. These four gerbil IGHC cDNA sequences will be useful for determining gerbil Ig isotypes and examining the expression of gerbil Ig mRNAs in response to parasitic and bacterial infections.

Partial sequence of Mongolian gerbil (Meriones unguiculatus) immunoglobulin gamma heavy chain constant region

We determined the sequence of the immunoglobulin gamma heavy-chain constant (IGHC) region of the Mongolian gerbil (Meriones unguiculatus). To isolate a part of the IGHC complementary DNA, we designed primers on the basis of highly conserved sequences in mouse, rat and hamster. The deduced IGHC is structurally similar to counterparts in other mammalian species and shows 84.6% identity to the IGHC of hamster IgG, 76.6% to rat IgG1, 83.3% to rat IgG2a, 78.1% to mouse IgG1, 81.8% to mouse IgG2a, 79.1% to mouse IgG2b and 79.2% to mouse IgG3 at the nucleotide level. The results suggest that gerbil IgG is closely related to hamster IgG and rat IgG2a.

Profiling the cellular immune response to multiple Brugia pahangi infections in a susceptible host

Human lymphatic filariasis is caused primarily by Brugia malayi and Wuchereria bancroffi. Unraveling this disease is complex, as people living in endemic areas exhibit a vast array of clinical states and immune responses. The Mongolian gerbil (Meriones unguiculatus)-B. pahangi model of human lymphatic filariasis has provided much information on immune parameters associated with filarial infection. Prior investigations in our laboratory have shown that gerbils closely mimic a subset of patients classified as microfilaremic but asymptomatic, a group that comprises the majority of people living in endemic areas. Worm recovery data suggest that gerbils carrying current B. pahangi infections do not show any resistance to subsequent subcutaneous B. pahangi infections. The aim of the present studies was to investigate the T cell cytokine response in gerbils receiving multiple infections of B. pahangi as a means of mimicking the conditions experienced by people in endemic areas. The T cell cytokine profile generated by multiply infected gerbils was not different from that previously generated by gerbils infected only once with B. pahangi. Gerbils infected multiple times with B. pahangi showed a transient increase in IL-5, which corresponded to the increased eosinophil levels previously reported from multiply infected gerbils. Chronically infected gerbils showed elevated IL-4 mRNA levels, as has been reported from gerbils infected only once with B. pahangi. Chronic infections were also associated with a state of immune hyporesponsiveness, as determined by the characterization of lymphatic thrombi and lymphoproliferation of spleen and renal lymph node cells to worm antigen.

Gerbil interleukin-18 and caspase-1: cloning, expression and characterization

We are reporting the molecular cloning of gerbil interleukin-18 (IL-18) and caspase-1. The cDNAs encoding the molecules were cloned by cross-species reverse transcriptase-polymerase chain reaction (RT-PCR) and 5'/3' rapid amplification of cDNA ends (RACE). COS-7 cells transfected with plasmids encoding pro-IL-18 and caspase-1 precursor expressed the two proteins intracellularly. When the cells were lysed in the presence of dithiothreitol, caspase-1 precursor became active and converted pro-IL-18 into mature IL-18. A partially purified preparation of gerbil mature IL-18 was bioactive, as it stimulated the proliferation of gerbil spleen cells in a dose-dependent manner.

Prospect for an Entamoeba histolytica Gal-lectin-based vaccine

Entamoeba histolytica is the aetiological agent of invasive amoebiasis, the third leading parasitic cause of mortality in the world. The disease can be easily cured by chemotherapy; however, prevention, mainly in the form of vaccination, could greatly decrease the incidence of the disease, and possibly help in its eradication. The parasite's surface galactose and N-acetyl-d-galactosamine-inhibitable adherence lectin (Gal-lectin) is highly antigenic and is the most promising subunit vaccine candidate. We have generated a Gal-lectin-based DNA vaccine and tested its immunogenicity in mice. Although further optimization will probably be required, this vaccine could help in the generation of an amoebiasis DNA vaccine for use in humans.