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Toxoplasma gondii, an intracellular zoonotic protozoan parasite, is possibly the most widespread parasite of warm-blooded animals and can cause serious public health problems and economic losses worldwide. TgCDPK2, a member of the T. gondii calcium-dependent protein kinase family, was recently identified as an essential regulator for viable cyst development in T. gondii. In the present study, we evaluated the protective immunity induced by DNA vaccination based on a recombinant eukaryotic plasmid, pVAX-TgCDPK2, against acute toxoplasmosis in mice. BALB/c mice were intramuscularly immunized with pVAX-TgCDPK2 plasmid and then challenged by infection with the highly virulent RH strain of T. gondii. The specific immune responses and protective efficacy against T. gondii were analyzed by cytokine and serum antibody measurements, lymphocyte proliferation assays, flow cytometric on lymphocytes and the survival time of mice after challenge. Our results showed that mice immunized with pVAX-TgCDPK2 could elicit special humoral and cellular responses, with higher levels of IgG antibody, and increased levels of Th1-type cytokines IFN-γ, IL-12(p70), and CD3 + CD4 + CD8 − and CD3 + CD8 + CD4 − T cells, and had a prolonged survival time (14.0 ± 2.32 days) compared to control mice. These results demonstrate that pVAX-TgCDPK2 is a potential vaccine candidate against acute toxoplasmosis.

Hymenolepis nanais a common tapeworm that parasitizes in the small intestine of rodent animals and humans. The present study examined the sequence diversity of three mitochondrial (mt) genes namely NADH dehydrogenase subunits 5 (nad5), small subunit ribosomal RNA (rrnS), and ATPase subunit 6 (atp6) ofH. nanafrom mice in different geographical regions of China. A part of thenad5 (pnad5), completerrnS andatp6 genes were amplified separately from individualH. nanaisolates using polymerase chain reaction (PCR) and then sequenced. The sequences of pnad5,rrnS, andatp6 were 710 bp, 704–711 bp, and 516 bp in length, respectively. The A + T contents of the sequences were 70.1–73.5% (pnad5), 70.1–71.7% (rrnS), and 76.6–77.9% (atp6). Sequence variation withinH. nanawas 0–1.4% foratp6, 0–1.7% forrrnS, and 0–0.7% for pnad5. The inter-specific sequence differences betweenH. nanaandHymenolepis diminutawere significantly higher, which was 31.6–31.7% (pnad5), 16.1–17.6% (rrnS), and 26.5–27.1% (atp6). Phylogenetic analysis based on the combined three sequences using the maximum parsimony (MP) method supported thatH. nanais a species complex or “cryptic” species. These findings demonstrated clearly the usefulness of the three mtDNA sequences for population genetics and systematic studies ofH. nanaof human and animal health significance. [ABSTRACT FROM AUTHOR]