[7]. Moreover, leptospires are very successful pathogens that can
infect all mammals, as well as birds, amphibians, reptiles, and possibly fish, and are able to escape from the host immune system.
However, virulence factors associated with these pathogens and
their interactions between leptospires and the host immune system
remain largely unknown [8, 9].
Historically, animal models have been most helpful for studying
leptospirosis, in particular to characterize the pathophysiology of
the disease, the host immune response to infection, as well as
pathogen-associated virulence factors. In 1915, Inada and Ido
showed that the spirochetes they had found in the blood of a
patient suffering from Weil’s disease was the causative agent of
the disease [10, 11]. To come to that conclusion, they performed
experimental infections using monkeys, rabbits, rats, and guinea
pigs and found that only guinea pigs developed clinical signs,
including conjunctival congestion, jaundice, and hemorrhage.
Moreover, the first described spirochete was found in the liver of
a guinea pig injected with the blood of a patient suffering from
Weil’s disease [11]. Since then, susceptible animals, mainly hamsters, gerbils, and guinea pigs, have extensively been used to study
acute lethal leptospirosis, whereas resistant mice and rats recapitulate sub-lethal leptospirosis and subsequent chronic renal
colonization [4].
The hamster model has been described as a model of choice for
accidental Leptospira infections, as are human infections, especially
for the development of leptospiral vaccine and antibiotic treatment
studies, for which data describing the host-Leptospira interactions
are essential [12]. The latter is our topic of interest in the laboratory, and we aim for this chapter to describe a typical experimental
infection procedure on golden Syrian hamsters we rely on for
characterizing the host immune response to a Leptospira infection
and investigating its role in the outcome of the disease [13]. Indeed,
results from experiments on intraperitoneally infected hamsters
notably suggest that a dramatic cytokine production imbalance
might be involved in the development of severe forms of leptospirosis in susceptible hosts [14–16]. We will also describe the collection and conservation methods of blood and organs from infected
and matching control animals destined to be submitted to total
DNA or RNA extraction. Indeed, we will describe quantitative
methods for assessing (1) bacterial burden, through the detection
of leptospiral genes in total extracted DNA, and (2) host immune
response by measuring the expression of immune mediators in total
extracted RNA. In both cases, we will provide details on our use of
quantitative PCR (qPCR), which has become the standard molecular tool for quantification purposes due to its high sensitivity.
Moreover, this technique has proven particularly instrumental for
animal models, like golden Syrian hamsters, lacking the immunological tools necessary for protein quantification. It should be noted
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Julie Cagliero et al.
infect all mammals, as well as birds, amphibians, reptiles, and possibly fish, and are able to escape from the host immune system.
However, virulence factors associated with these pathogens and
their interactions between leptospires and the host immune system
remain largely unknown [8, 9].
Historically, animal models have been most helpful for studying
leptospirosis, in particular to characterize the pathophysiology of
the disease, the host immune response to infection, as well as
pathogen-associated virulence factors. In 1915, Inada and Ido
showed that the spirochetes they had found in the blood of a
patient suffering from Weil’s disease was the causative agent of
the disease [10, 11]. To come to that conclusion, they performed
experimental infections using monkeys, rabbits, rats, and guinea
pigs and found that only guinea pigs developed clinical signs,
including conjunctival congestion, jaundice, and hemorrhage.
Moreover, the first described spirochete was found in the liver of
a guinea pig injected with the blood of a patient suffering from
Weil’s disease [11]. Since then, susceptible animals, mainly hamsters, gerbils, and guinea pigs, have extensively been used to study
acute lethal leptospirosis, whereas resistant mice and rats recapitulate sub-lethal leptospirosis and subsequent chronic renal
colonization [4].
The hamster model has been described as a model of choice for
accidental Leptospira infections, as are human infections, especially
for the development of leptospiral vaccine and antibiotic treatment
studies, for which data describing the host-Leptospira interactions
are essential [12]. The latter is our topic of interest in the laboratory, and we aim for this chapter to describe a typical experimental
infection procedure on golden Syrian hamsters we rely on for
characterizing the host immune response to a Leptospira infection
and investigating its role in the outcome of the disease [13]. Indeed,
results from experiments on intraperitoneally infected hamsters
notably suggest that a dramatic cytokine production imbalance
might be involved in the development of severe forms of leptospirosis in susceptible hosts [14–16]. We will also describe the collection and conservation methods of blood and organs from infected
and matching control animals destined to be submitted to total
DNA or RNA extraction. Indeed, we will describe quantitative
methods for assessing (1) bacterial burden, through the detection
of leptospiral genes in total extracted DNA, and (2) host immune
response by measuring the expression of immune mediators in total
extracted RNA. In both cases, we will provide details on our use of
quantitative PCR (qPCR), which has become the standard molecular tool for quantification purposes due to its high sensitivity.
Moreover, this technique has proven particularly instrumental for
animal models, like golden Syrian hamsters, lacking the immunological tools necessary for protein quantification. It should be noted
244
Julie Cagliero et al.