Molecular cloning and characterization of the circumsporozoite protein gene of Plasmodium inui isolated from Formosan macaques (Macaca cyclopis) in Taiwan.

We characterized the complete nucleic and amino acid sequences of the Plasmodium inui circumsporozoite protein (Pincsp) gene and analyzed nucleotide diversity across the entire Pincsp gene by using 7 field isolates and strains Taiwan I and II obtained from Formosan macaques (Macaca cyclopis) in Taiwan. The length of the circumsporozoite protein ( CSP ) gene ranged from 1077 to 1125 bp. Size polymorphisms were due to variations in the number of tandem repeat units. The non-repetitive (NR) region exhibited high homology (99.1 ∼ 100 and 98.7 ∼ 100% at the nucleotide and amino acid levels, respectively) and was conserved among the variants (nucleotide diversities, π, of the 5'NR and 3'NR regions were 0.00364 and 0.00392, respectively). In the central repetitive (CR) region, we decomposed the sequences into 2 kinds of repeating amino acid motifs, i.e., a repeat unit R1, PA(P/A)(P/A)A(E)GG (n  =  11-13), and a following repeat unit R2: P(A/G)(A/P/G)(P/Q)AQ(N/K) (n  =  9-10). Analyzing these repeat sequences showed evidence of 3 genetic mechanisms for generating variations in the repeats of the Pincsp gene, i.e., point mutation, insertion, and recombination. These findings suggest that polymorphisms in the Pincsp gene are essentially limited to the CR region, which showed much greater variability in terms of length, number of repeats, and sequence.

Prevalence and molecular characterization of Plasmodium inui among Formosan macaques (Macaca cyclopis ) in Taiwan.

Since the 1970s, no information on simian malaria has been documented in Taiwan, an area that is free from human malaria. To update the prevalence of simian malaria, a molecular-based survey was performed. Blood samples from 286 Formosan macaques ( Macaca cyclopis ) were tested for Plasmodium species by microscopy and nested polymerase chain reaction. Furthermore, the field isolates were characterized by sequencing the 42-kDa fragment of the merozoite surface protein 1 (MSP-1(42)). Of the 286 blood samples analyzed, 7 (2.4%) were positive by microscopy and nested PCR. All malaria-infected Formosan macaques were those collected from southern Taiwan, whereas no evidence of malarial parasites was observed among monkeys from eastern and northern Taiwan. Molecular and phylogenetic analyses based on the asexual stage small subunit ribosomal RNA (SSU rRNA) gene clearly identified these samples as a single infection with Plasmodium inui . Furthermore, phylogenetic analysis of the MSP-1(42) gene showed that the 7 field isolates were closely related to P. inui strains Taiwan I and II, which were obtained from Formosan macaques in 1963. These findings indicate that P. inui is the only cause of simian malaria in Taiwan, has been circulating in Formosan macaques at least for 46 yr, and has a geographic preference for southern Taiwan.

Prevalence and phylogenetic analysis of hepatitis B virus among nonhuman primates in Taiwan.

Hepatitis B virus (HBV) is a public health problem worldwide, and apart from infecting humans, HBV has been found in nonhuman primates. This study investigated the prevalence and phylogenetic analysis of hepatitis B virus (HBV) and hepatitis D virus (HDV) among nonhuman primates in Taiwan, an area where human HBV remains endemic. Serum samples from 286 captive nonhuman primates (i.e., 32 great apes [Pan troglodytes and Pongo pygmaeus], 42 gibbons [Hylobates sp. and Nomascus sp.], and 212 Cercopithecidae monkeys) were collected and tested for the presence of HBV- and HDV-specific serologic markers. None of the Cercopithecidae monkeys were reactive against serologic markers of HBV. In contrast, 21.9% (7/32) of great apes and 40.5% (17/42) of gibbons tested positive for at least one serologic marker of HBV. Of these, five gibbons were chronic HBV carriers, characterized by presence of HBV DNA and hepatitis B surface antigen in the serum. HBV DNA was also detected in the saliva of three of the chronic carries. None of these HBV carrier gibbons exhibited symptoms or significant change in serum clinical chemistry related to HBV infection. Phylogenetic analysis of the complete HBV genome revealed that gibbon viruses clustered with other HBV isolates of great apes and gibbons from Southeast Asia and separately from human-specific HBV. None of the HBV-infected animals were reactive against HDV. These findings indicate that HBV found in these animals is indigenous to their respective hosts and might have been introduced into Taiwan via the direct import of infected animals from Southeast Asia. To reduce the horizontal and vertical transmission of HBV in captive animals, the HBV carriers should be kept apart from uninfected animals.