VIOLIN: Vaccine Investigation and Online Information Network

Pathogen Page

Leishmania amazonensis

I. General Information

1. NCBI Taxonomy ID:

2. Disease:

Leishmaniasis

3. Introduction

The different Leishmania species cause a broad spectrum of human diseases. L. amazonensis is known to be associated with cutaneous, diffuse cutaneous, and visceral leishmaniasis in South and Central America. The pathological mechanisms responsible for the variable outcomes of infection in humans are not fully understood; however, it is generally agreed that long-lasting immunity against reinfection can be developed in cutaneous leishmaniasis patients. Several vaccination trials have demonstrated that killed L. amazonensis can induce protection from natural infection. However, the efficacy of heat-killed vaccines against Leishmania has been extremely low or highly variable within the same study. Live parasites have been used as a vaccine strategy, and although they are highly effective in inducing immunity, this strategy has been virtually abandoned due to safety issues associated with injecting virulent organisms (Campbell et al., 2003).

4. Host Protective Immunity

Protective mechanisms in L. amazonensis are unclear. During L. amazonensis infection, BALB/c mice display a mixed profile of both Th1 and Th2 responses, although the implications of this mixed profile are ambiguous. However, the necessity for vaccines to induce a Th1-dominant response for these species of Leishmania appears to be consequential for protection (Campbell et al., 2004). The immune responses induced against L. (L.) amazonensis have showed a distinct pattern from that described for L. (L.) major. While mice that are resistant or susceptible to infection with L. (L.) major exhibit immune responses polarized to Th1 and Th2, respectively, susceptibility to L. (L.) amazonensis can not be correlated to an increased Th2 response (Fedeli et al., 2010).

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