The effect of feeding on different hosts on the egg proteins in Haemaphysalis qinghaiensis tick

The majority of ixodid ticks display host-specificity to varying extents. Feeding on different hosts affects their development and reproduction. Consequences can be analyzed at the level of the egg, as it is the initial stage of tick development. Tick egg proteins are abundant and diverse, providing nutrients for embryonic development. However, studies on tick egg profiles are scarce. In this study, we aimed to analyze whether feeding Haemaphysalis qinghaiensis ticks on the yaks (Bos grunniens) and domestic sheep (Ovis aries) has an impact on the variety and variability of the egg proteome. Detached engorged females were used to lay eggs, which were then collected, dewaxed, and subjected to protein extraction. The extracted egg proteins were enzymatically digested using Filter-Aided Sample Preparation (FASP), and the unique peptides were separated and detected by Liquid Chromatography-tandem Mass Spectrometry (LC-MS/MS). The MS data were searched against the previously constructed whole tick transcriptome library of H. qinghaiensis, and the UniProt database for the identification of tick-derived egg proteins. The analysis revealed 49 and 53 high-confidence proteins identified in eggs collected from B. grunniens (EggBg) and O. aries (EggOa), respectively. Of these, 46 high-confidence proteins were common to both egg types, while three were unique to EggBg and seven to EggOa. All the identified proteins mainly belonged to enzymes, enzyme inhibitors, transporters, and proteins with unknown functions. The differential abundance analysis showed that nine proteins were significantly more present in EggBg, while six were significantly more present in EggOa. Overall, enzymes were the most diverse group, while vitellogenin (Vg) was the most abundant. Blood meal uptake on different hosts has a certain effect on the egg proteome composition and the abundance of some proteins, but it may also lead to compensation of protein roles.

Tick salivary protein Cystatin: structure, anti-inflammation and molecular mechanism

Ticks are blood-sucking ectoparasites that secrete immunomodulatory substances in saliva to hosts during engorging. Cystatins, a tick salivary protein and natural inhibitor of Cathepsins, are attracting growing interest globally because of the immunosuppressive activities and the feasibility as an antigen for developing anti-tick vaccines. This review outlines the classification and the structure of tick Cystatins, and focuses on the anti-inflammatory effects and molecular mechanisms. Tick Cystatins can be divided into four families based on structures and cystatin 1 and cystatin 2 are the most abundant. They are injected into hosts during blood feeding and effectively mitigate the host inflammatory response. Mechanically, tick Cystatins exert anti-inflammatory properties through the inhibition of TLR-NF-κb, JAK-STAT and p38 MAPK signaling pathways. Further investigations are crucial to confirm the reduction of inflammation in other cell types like neutrophils and mast cells, and fully elucidate the underlying mechanism (like the structural mechanism) to make Cystatin a potential candidate for the development of novel anti-inflammation agents.

Saliva proteome of partially- and fully-engorged adult female Haemaphysalis flava ticks

Tick saliva is a reservoir of bioactive proteins. Saliva protein compositions change dynamically during blood-feeding. Decipherment of protein profiles in different blood-feeding stages may bring deeper insight into tick feeding physiology and provide targets for immunologic control alternatives. However, having the infancy of tick genome sequencing, assembly, annotation, and limited knowledge of tick salivary proteins restrain the data interpretation. Here, we aimed to depict the saliva protein profile in partially- (PE) and fully-engorged (FE) Haemaphysalis flava ticks, with a special focus on the analysis of those uncharacterized proteins. Saliva was collected from PE and FE adult female H. flava ticks. Saliva proteins were analyzed by high-performance liquid chromatography-tandem mass spectrometry (HPLC/MS-MS). MS data were searched against an in-house salivary gland transcriptome library for identification of tick-derived proteins. Abundances of proteins were compared between PE and FE ticks. The uncharacterized proteins detected in saliva were further bioinformatically analyzed. In total, 614 proteins were identified including 94 host proteins and 520 tick-derived proteins. The 226 tick-derived high-confidence proteins were classified into 10 categories: transporters, enzymes, protease inhibitors, immunity-related proteins, lipocalins, glycine-rich proteins, muscle proteins, secreted proteins, uncharacterized proteins and others. A total of 98 proteins were shared in both PE and FE with 74 only in PE and 54 only in FE. Abundances of 24 shared proteins were significantly higher in PE. The profile of top 15 most abundant proteins was also different between PE and FE ticks. The 65 uncharacterized proteins detected in tick saliva were branched into subclusters 1 A, 1B, 2, 3 A, 3B and 3 C based on particular motifs like RGD, LRR, indicating their diverse predicted functions like anti-coagulation, regulation of innate immune, or other functions. This study provides and compares saliva proteomes of H. flava ticks in two feeding stages with special cluster analysis on the uncharacterized proteins. Further investigations are needed to confirm the roles of these uncharacterized proteins in ticks.

Identification of a new species of Ixodes Latreille, 1795 (Acari: Ixodidae), parasite of hog badgers (Carnivora: Mustelidae) in China

Ixodes hunanensis n. sp. (Acari: Ixodidae), is identified based on the morphological characteristics and molecular biological analyses of males and females ex hog badger, Arctonyx collaris Cuvier (Carnivora: Mustelidae) from China. Adults of this new species are similar to those of other species of the subgenus Pholeoixodes Schulze, 1942, from which they can be distinguished by the shape of basis capituli, development of cornua, size of porose areas, shape, and size of spurs on coxae and phylogenetic analyses of the cox1 and 16S rRNA sequences.

Comparative analysis of the anticoagulant activities and immunogenicity of HSC70 and HSC70TKD of Haemaphysalis flava

BACKGROUND

Haemaphysalis flava is a hematophagous ectoparasite that acquires the nutrition needed for development and reproduction by sucking blood and digesting the blood meal. During blood-sucking and blood-meal digestion, the prevention of blood coagulation is important for this tick. Previous studies have shown that heat shock cognate 70 (HSC70) protein has certain anticoagulant activities, but its immunogenicity remains unclear. Also, whether the mutation of individual bases of the TKD-like peptide of HSC70 through the overlap extension method can change its anticoagulant activities and immunogenicity remains to be investigated.

METHODS

The gene encoding the HSC70 protein was cloned from a complementary DNA library synthesized from H. flava. The coding gene of the TKD-like peptide of HSC70 was mutated into a TKD peptide coding gene (HSC70^TKD) using the overlap extension method. Escherichia coli prokaryotic expression plasmids were constructed to obtain the recombinant proteins of HSC70 (rHSC70) and HSC70^TKD (rHSC70^TKD). The purified rHSC70 and rHSC70^TKD were evaluated at different concentrations for anticoagulant activities using four in vitro clotting assays. Emulsifying recombinant proteins with complete and incomplete Freund's adjuvants were subcutaneously immunized in Sprague Dawley rats. The serum antibody titers and serum concentrations of interferon-gamma (IFN-γ) and interleukin-4 (IL-4) were detected using an indirect enzyme-linked immunosorbent assay to assess the immunogenicity of rHSC70 and rHSC70^TKD.

RESULTS

The open reading frame of HSC70 was successfully amplified and found to have a length of 1958 bp. The gene encoding the TKD-like peptide of HSC70 was artificially mutated, with the 1373-position adenine (A) of the original sequence mutated into guanine (G), the 1385-position cytosine (C) mutated into G and the 1386-position G mutated into C. rHSC70 and rHSC70^TKD that fused with His-tag were obtained using the expression plasmids pET-28a-HSC70 and pET-28a-HSC70^TKD, respectively. rHSC70 and rHSC70^TKD prolonged the thrombin time (TT) and reduced the fibrinogen (FIB) content in the plasma, but did not affect the prothrombin time (PT) or activated partial thromboplastin time (APTT) when compared to the negative control. Interestingly, the ability of rHSC70^TKD to prolong the TT and reduce the FIB content in the plasma was better than that of rHSC70. The specific antibody titers of both rHSC70 and rHSC70^TKD in rat serum reached 1:124,000 14 days after the third immunization. The serum concentration of IFN-γ in the rHSC70^TKD group was higher than that in the rHSC70 group. The rHSC70 group has the highest serum concentration of IL-4, and the serum concentration of IL-4 in the rHSC70^TKD group was higher than that in the negative group.

CONCLUSIONS

rHSC70 and rHSC70^TKD exhibited anticoagulant activities by prolonging the TT and reducing the FIB content in vitro. rHSC70^TKD had better anticoagulant activities than rHSC70. Both rHSC70 and rHSC70^TKD had good immunogenicity and induced humoral and cellular immunity.

Protein profiling of hemolymph in Haemaphysalis flava ticks

Background

Tick hemolymph bathes internal organs, acts as an exchange medium for nutrients and cellular metabolites, and offers protection against pathogens. Hemolymph is abundant in proteins. However, there has been limited integrated protein analysis in tick hemolymph thus far. Moreover, there are difficulties in differentiating tick-derived proteins from the host source. The aim of this study was to profile the tick/host protein components in the hemolymph of Haemaphysalis flava.

Methods

Hemolymph from adult engorged H. flava females was collected by leg amputation from the Erinaceus europaeus host. Hemolymph proteins were extracted by a filter-aided sample preparation protocol, digested by trypsin, and assayed by liquid chromatography–tandem mass spectrometry (LC–MS/MS). MS raw data were searched against the UniProt Erinaceidae database and H. flava protein database for host- and tick-derived protein identification. Protein abundance was further quantified by intensity-based absolute quantification (iBAQ).

Results

Proteins extracted from hemolymph unevenly varied in size with intense bands between 100 and 130 kDa. In total, 312 proteins were identified in the present study. Therein 40 proteins were identified to be host-derived proteins, of which 18 were high-confidence proteins. Top 10 abundant host-derived proteins included hemoglobin subunit-α and subunit-β, albumin, serotransferrin-like, ubiquitin-like, haptoglobin, α-1-antitrypsin-like protein, histone H2B, apolipoprotein A-I, and C3-β. In contrast, 169 were high-confidence tick-derived proteins. These proteins were classified into six categories based on reported functions in ticks, i.e., enzymes, enzyme inhibitors, transporters, immune-related proteins, muscle proteins, and heat shock proteins. The abundance of Vg, microplusin and α-2-macroglobulin was the highest among tick-derived proteins as indicated by iBAQ.

Conclusions

Numerous tick- and host-derived proteins were identified in hemolymph. The protein profile of H. flava hemolymph revealed a sophisticated protein system in the physiological processes of anticoagulation, digestion of blood meal, and innate immunity. More investigations are needed to characterize tick-derived proteins in hemolymph.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05287-7.

Metagenomics of the midgut microbiome of Rhipicephalus microplus from China

Background

Ticks, which are ectoparasites of animals, may carry multiple pathogens. The cattle tick Rhipicephalus microplus is an important bovine parasite in China. However, the midgut microbiome of R. microplus from China has not been characterized via metagenomic methods.

Methods

Rhipicephalus microplus were collected from cattle in the city of Changsha in Hunan province, China. The DNA of the midgut contents was extracted from fully engorged adult female R. microplus. A DNA library was constructed and sequenced using an Illumina HiSeq sequencing platform. SOAPdenovo software was used to assemble and analyze the clean data. The latent class analysis algorithm applied to system classification by MEGAN software was used to annotate the information on the species’ sequences. DIAMOND software was used to compare unigenes with the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, and functional annotation was carried out based on the results of the comparison.

Results

The dominant phyla in the five samples were Firmicutes, Proteobacteria, and Actinobacteria. Streptococcus, Mycobacterium, Anaplasma, Enterococcus, Shigella, Lactobacillus, Brachyspira, Pseudomonas, Enterobacter, Bacillus, and Lactococcus were the dominant genera in the five samples. The endosymbiotic bacterium Wolbachia was also detected in all of the samples. Mycobacterium malmesburyense, Streptococcus pneumoniae, Anaplasma phagocytophilum, Enterococcus faecium, Shigella sonnei, Enterococcus faecalis, Lactobacillus casei, Brachyspira hampsonii, Pseudomonas syringae, Enterobacter cloacae, and Lactococcus garvieae were the dominant species in the five samples. In addition to these bacterial species, we also detected some eukaryotes, such as Rhizophagus irregularis, Enterospora canceri, Smittium culicis, Zancudomyces culisetae, Trachipleistophora hominis, and viruses such as orf virus, human endogenous retrovirus type W, enzootic nasal tumor virus of goats, bovine retrovirus CH15, and galidia endogenous retrovirus in all of the samples at the species level. The results of the annotated KEGG pathway predictions for the gene functions of the midgut microflora of R. microplus indicated genes involved in lipid and amino acid metabolism, infectious diseases (e.g., Streptococcuspneumonia infection, human granulocytic anaplasmosis, Shigellasonnei infection, Salmonella enterica infection, and pathogenic Escherichia coli infection), and cancer.

Conclusions

Our study revealed that the midgut microbiome of R. microplus is not only composed of a large number of bacteria, but that a portion also comprises eukaryotes and viruses. The data presented here enhance our understanding of this tick’s midgut microbiome and provide fundamental information for the control of ticks and tick-borne diseases.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05161-6.

Cloning, expression, and function of ferritins in the tick Haemaphysalis flava

The full-length cDNA of two ferritins of Haemaphysalis flava were cloned after which recombinant Hf-FER1 and Hf-FER2 were expressed and their function was analyzed. In addition, RNA interference (RNAi) based on the injection of Hf-fer1 or Hf-fer2 dsRNA into fully engorged female ticks was performed. The cDNA encoding Hf-FER1 is 834 bp in length. It contains an iron-responsive element in the 5' untranslated region and encodes 174 amino acid residues. The full-length cDNA of Hf-FER2 contains 696 bp and encodes 199 amino acids, including a putative signal peptide sequence. Hf-FER1 and Hf-FER2 both have the ferroxidase iron center and the ferrihydrite nucleation center. The evolutionary relationship of Hf-FER1 and Hf-FER2 was established, and the predicted quaternary structures were assembled as typical spherical shells composed of 24 subunits which was demonstrated by nature PAGE. Real-time PCR showed that Hf-fer1 and Hf-fer2 were expressed in all developmental stages, with the highest expression in fully engorged females. The expression of Hf-fer1 and Hf-fer2 were relatively high in unfed larvae. Hf-fer1 was expressed in all tissues and was especially abundant in the salivary glands of fully engorged females. In contrast, the highest levels of Hf-fer2 were found in the midgut of fully engorged females, and no expression was found in the salivary glands of this life stage. Both recombinant Hf-FER1 and Hf-FER2 had iron-binding capabilities. Silencing of both Hf-fer1 and Hf-fer2 affected fecundity. Compared to the control, the percentage of ticks that laid eggs in the Hf-fer1 and Hf-fer2 RNAi groups was 73.3% and 66.7%, respectively. The silenced ticks that laid eggs had lower egg weight to body weight ratios, and the eggs had abnormal morphologies. The hatchability of eggs with normal morphology in the Hf-fer1 and Hf-fer2 silenced groups was 47.8% and 22.8%, respectively, which was significantly different from the control group (P < 0.005). These findings indicate that Hf-FER1 and Hf-FER2 play important roles in the iron storage of H. flava.

Microbiome analysis of the midguts of different developmental stages of Argas persicus in China

Argas persicus is an ectoparasite of poultry. The bacterial community structure and the pathogenic bacteria associated with different developmental stages of A. persicus have implications for control. Argas persicus were collected from chickens in the city of Jiuquan in Gansu, China. Bacterial DNA was extracted from the midgut contents of blood engorged larvae, nymphs and adult females. The V3-V4 hypervariable regions of 16S rRNA genes were sequenced using the IonS5™XL platform. Identification of Rickettsia spp. and detection of Coxiella burnetii were performed using PCR on target genes. The bacterial diversity within larvae was the highest and the bacterial diversity within nymphs was greater than that of adults. At different classification levels, seven bacterial phyla were common phyla, 27 genera were common genera, and 18 species were common species in the three samples. At the phylum level, Proteobacteria showed a marked predominance in all samples. Rickettsia, Stenotrophomonas, Spiroplasma, and Coxiella were the dominant bacteria at the genus level. The Rickettsia species in A. persicus was identified as Rickettsia hoogstraalii and the Coxiella species was identified as a Coxiella-like endosymbiont. Additionally, some bacterial species such as Pseudomonas geniculata, Sphingomonas koreensis, and Acinetobacter haemolyticus were reported here for the first time in A. persicus.

[Incidence of unintended pregnancy within 2 years after delivery and its influencing factors in China]

Objective: To investigate the present situation of unintended pregnancy within two years postpartum and its influencing factors in China. Methods: Participants who delivered a live birth at 60 hospitals in 15 provinces in the eastern, central and western regions of China during July 2015 to June 2016 were interviewed by using structured questionnaire. Information on occurrence of unintended pregnancy within 2 years after delivery, postpartum contraceptive use, sexual resumption, breastfeeding, and women's socio-demographic characteristics, and so on, were collected. Life-table analysis, cluster log-rank tests and a 2-level Cox regression model were used for data analysis. Results: A total of 18 045 postpartum women were investigated. The cumulative 1- and 2-year unintended pregnancy rates after delivery were 5.3% (95%CI: 4.5%－6.1%) and 13.1% (95%CI: 11.3%－14.8%), respectively. Cox regression model analysis showed that the risk of unintended pregnancy within 2 years postpartum were increased in younger women, ethnic minorities, women with abortion history, and those who had a vaginal delivery with short lactation time and late postpartum contraceptive initiation (all P<0.01). The risk of postpartum unintended pregnancy was not associated with geographic regions and hospitals where women gave a birth (all P>0.05). Conclusions: In China, the risk of unintended pregnancy within 2 years after delivery is relatively high. Service institutions and service providers should improve the quality of postpartum family planning services, promote the use of high effect contraceptive methods, and educate women to use a method at the time of their sexual resumption or even before.

Characterization of AV422 from Haemaphysalis flava ticks in vitro

Ticks are hematophagous ectoparasites and cause a major public health threat worldwide. Development of anti-tick vaccines is regarded to be an optimal alternative for tick control. AV422, a unique protein in ticks, is secreted into hosts during blood-feeding, but its roles are not confirmed in Haemaphysalis flava ticks. We retrieved a gene fragment encoding AV422 from a transcriptome dataset of H. flava, and based on it, we reconstructed the full length of AV422 from H. flava (Hf-AV422) by rapid amplification of cDNA ends. Expression profiles of Hf-AV422 in whole ticks and organs of different engorgement levels were determined by qPCR. Then its opening reading frame (ORF) was expressed in Escherichia coli strain BL21 (DE3). The prothrombin time (PT), activated partial thromboplastin time (APTT) and thrombin time (TT) assays were conducted to test anticoagulant activities of the purified recombinant protein (rHf-AV422). The full length of AV422 was 1152 bp. Hf-AV422 showed to be conserved as indicated by multiple sequence alignment. Expression of Hf-AV422 was significantly higher in salivary glands and cuticles than in ovaries. Its expression in whole ticks decreased during engorgement with the highest levels in 1/4 engorged ticks. rHf-AV422 prolonged PT, APTT and TT when incubated with rabbit plasma. Our data demonstrated that Hf-AV422 is a conserved salivary protein with anticoagulant activity. Further studies are needed to test in detail its functional properties to ensure it an adequate antigen candidate for the development of broad-spectrum vaccines against ticks.

G-CSF Inhibits Pulmonary Fibrosis by Promoting BMSC Homing to the Lungs via SDF-1/CXCR4 Chemotaxis

Bone marrow mesenchymal stem cells (BMSCs) have multi-lineage differentiation potential and play an important role in tissue repair. Studies have shown that BMSCs gather at the injured tissue site after granulocyte-colony stimulating factor (G-CSF) administration. In this study, we first investigated whether G-CSF could promote BMSC homing to damaged lung tissue induced by bleomycin (BLM) and then investigated whether SDF-1/CXCR4 chemotaxis might be involved in this process. Next, we further studied the potential inhibitory effect of G-CSF administration in mice with lung fibrosis induced by bleomycin. We examined both the antifibrotic effects of G-CSF in mice with bleomycin-induced pulmonary fibrosis in vivo and its effects on the proliferation, differentiation and chemotactic movement of cells in vitro. Flow cytometry, real-time PCR, transwell and Cell Counting Kit-8 (CCK-8) assays were used in this study. The results showed that both preventative and therapeutic G-CSF administration could significantly inhibit bleomycin-induced pulmonary fibrosis. G-CSF enhanced BMSC migration to lung tissues, but this effect could be alleviated by AMD3100, which blocked the SDF-1/CXCR4 axis. We also found that BMSCs could inhibit fibroblast proliferation and transdifferentiation into myofibroblasts through paracrine actions. In conclusion, G-CSF exerted antifibrotic effects in bleomycin-induced lung fibrosis, in part by promoting BMSC homing to injured lung tissues via SDF-1/CXCR4 chemotaxis.

Microbiome analysis of the saliva and midgut from partially or fully engorged female adult Dermacentor silvarum ticks in China

Dermacentor silvarum is widely distributed in northern China and transmits several pathogens that cause diseases in humans and domestic animals. We analysed the comprehensive bacterial community of the saliva and midgut from partially and fully engorged female adult D. silvarum. Dermacentor silvarum samples were collected from Guyuan, China. Bacterial DNA was extracted from the saliva and midgut contents of partially or fully engorged female adult D. silvarum. Sequencing of the V3-V4 hypervariable regions of the 16S rRNA genes was performed using the IonS5^TMXL platform. The bacterial diversity in saliva was higher than in the midgut. The bacterial diversity of saliva from fully engorged ticks was greater than in partially engorged tick saliva. The bacterial diversity in midguts from partially engorged ticks was greater than in fully engorged tick midguts. Proteobacteria was the most dominant bacterial phylum in all of the samples. Twenty-nine bacterial genera were detected in all of the samples. Rickettsia, Anaplasma, and Stenotrophomonas were the main genera. The symbionts Coxiella, Arsenophonus, and Wolbachia were also detected in all of the samples. Eight bacterial species were identified in all of the experimental samples. Anaplasma marginale was reported for the first time in D. silvarum.

A survey of proteins in midgut contents of the tick, Haemaphysalis flava, by proteome and transcriptome analysis

Tick blood meals are stored and digested in their midguts. Blood digestion is complex, and many proteins are involved. Study of the tick-derived proteins in the midgut content may aid in the discovery of active molecules that would be useful for anti-tick vaccines. We analyzed the midgut content proteomes of partially engorged female Haemaphysalis flava, fully engorged female H. flava, and hedgehog serum using liquid chromatography tandem-mass spectrometry and label-free quantitation. In this study, high-confidence protein profiling of tick midgut content was determined. Based on the search against our in-house transcriptome database, the 28 high-confidence proteins were identified. Of these, 17 were identified as tick-derived, and the rest were of unspecified origin (proteins that could not be differentiated as host-derived or tick-derived proteins). The function of these midgut content proteins identified here may involve nutrient transportation, anti-coagulation, erythrocyte lysis, detoxification, lipid metabolism, and immunization. The presence of hemoglobin suggested that the red blood cells were lysed in the gut lumen. The midgut contents contain a large amount of fibrinogen and it has the ability to clot immediately. The midgut contained mostly host-derived proteins, and these host proteins provide rich nutrients for tick development and reproduction. However, some intracellular proteins were also identified, suggesting the possibility of shedding of the midgut epithelium and ingestion of saliva during feeding. This finding advances our understanding of the digestive mechanism and will be useful in the screening of vaccine antigens.

Proteomic analysis of saliva from partially and fully engorged adult female Rhipicephalus microplus (Acari: Ixodidae)

Rhipicephalus microplus salivary gland secretes a number of complex bioactive proteins during feeding. These components are important in feeding and affect anti-coagulation, anti-inflammation and also have anti-microbial effects. In this study, tick saliva was collected from partially engorged female (PEF) and fully engorged female (FEF) ticks. Liquid chromatography tandem-mass spectrometry (LC-MS/MS) and isobaric tags for relative and absolute quantification (iTRAQ) were used to identify and quantify R. microplus salivary proteins. A total of 322 unique peptides were detected and 151 proteins were characterized in both PEF and FEF. Of these, 41 proteins are considered as high-confidence proteins. Fifteen high-confidence proteins were upregulated and six high-confidence proteins were downregulated (p < 0.05; PEF:FEF ratio ≥ 1.2 or PEF:FEF ratio ≤ 0.83); 17 high-confidence proteins are slightly changed (PEF:FEF ratio > 0.83 and < 1.2). These high-confidence proteins are involved in several physiological roles, including egg development, transportation of proteins, immunity and anti-microorganism, anti-coagulant, and adhesion. In comparison with PEF, the number of upregulated proteins exceeded the number of proteins downregulated. Salivary protein may be induced by the blood-meal and these proteins contribute to successful feeding.

Genetic variation in three mitochondrial genes among cattle tick Rhipicephalus microplus originating from four provinces of China

The cattle tick, Rhipicephalus microplus (formerly Boophilus microplus), is the most important blood-feeding ectoparasite of cattle in tropical and subtropical regions of the world. In this study, we examined sequence variability in three mitochondrial (mt) DNA (cox1, nad1, nad4) among cattle tick R. microplus originating from four provinces of China. A portion of cox1 (pcox1), nad1 (pnad1) and nad4 (pnad4) genes were amplified by polymerase chain reaction (PCR) separately from adult R. microplus individuals and the amplicons were subjected to sequence from both directions. The sequence of mt cox1, nad1, nad4 genes was 817 bp, 350 bp, and 794 bp in size, respectively. The intraspecific sequence variations within R. microplus were 0-8.6% for cox1, 0-4.9% for nad1 and 0-10.3% for nad4. However, the interspecific sequence differences among the members of the Rhipicephalus [R. sanguineus (JX416325) and R. turanicus (NC035946)] were significantly higher, being 16.9-20.5%, 18- 22.8%, 22.8-25.3% for pcox1, pnad1 and pnad4, respectively. In addition, genetic differences were 7.9-8.6% for cox1, 4.3-4.9% for nad1 and 10-10.3% for nad4 between the two detected lineages (R. microplus clade A and clade B). Phylogenetic analyses indicated that all the Rhipicephalus isolates from the present study represents R. microplus, supporting that R. microplus represents species complex. Our result provided an additional genetic evidence for the existence of species complex within R. microplus in China.

Cloning and Expression Profile of Glyceraldehyde-3-Phosphate Dehydrogenase in Haemaphysalis flava (Acari: Ixodidae)

Haemaphysalis flava (Acari: Ixodidae) harbors pathogenic microorganisms and transfers these to hosts during blood feeding. Proteomic analysis in the midgut contents of H. flava detected glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and contig 1683 was retrieved as a GAPDH gene fragment by searching our previous transcriptomic library. In the study, the 5' and 3' ends of contig 1683 were cloned by rapid amplification of cDNA ends (RACE) and a full length, 1340 bp cDNA of Hf-GAPDH was obtained. The open-reading frame had 999 bp and coded for 333 amino acids. Hf-GAPDH was predicted to have an N-terminal NAD binding domain and a C-terminal glyceraldehyde dehydrogenase catalytic domain. The molecular structure of Hf-GAPDH was analyzed and the evolutionary relationship also established. The GAPDH protein sequence was conserved among ticks. The expression pattern of Hf-GAPDH, analyzed by real-time PCR, significantly differed among life phases, feeding stages, and tissues. As the ticks grew, the expression level of Hf-GAPDH was up-regulated. The expression levels of Hf-GAPDH in salivary glands and midguts from half-engorged ticks were lower than the same tissues from engorged ticks. This study will provide reference data for the follow-up verification of the GAPDH-related function and the feasibility as a potential anti-tick vaccine.

HSC70 from Haemaphysalis flava (Acari: Ixodidae) exerts anticoagulation activity in vitro

Ticks and tick-borne diseases are major global health threats. During blood feeding, ticks insert their hypostomes into hosts and inject an array of anticoagulant molecules to maintain fluidity of the blood-meal. These anticoagulant molecules may provide insights into understanding the feeding biology of ticks and to develop vaccines against infestations. In Haemaphysalis flava, the heat shock cognate 70 (HSC70), a member of the heat shock protein (HSP) family, is differentially expressed in salivary glands at different levels of engorgement during blood feeding. However, its function in ticks is largely not known. The present study was designed to explore the possible effects of HSC70 on the plasma. The open reading frame (ORF) of HSC70 was expressed in a prokaryotic system, and recombinant HSC70 (rHSC70) was purified and characterized. The anticoagulation activity of rHSC70 was estimated by measuring prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT) and fibrinogen (FIB) with/without its inhibitor, VER155008. The results demonstrated that rHSC70 from H. flava extended TT (P < 0.001) and FIB clotting times (>300 s), but showed little effect on PT and APTT. Adding an inhibitor reversed anticlotting effects of rHSC70 on TT and FIB. These data indicate that rHSC70 is an anticoagulant agent, and the anticlotting activity likely attributes to the inhibition of thrombin and the transformation of fibrinogen into fibrin.

First Report of Ixodes nipponensis Infection in Goats in China

Ticks are obligate blood-sucking ectoparasites that infect a wide range of animals and humans, causing a variety of both human and animal diseases around the world. Ixodes nipponensis is the most commonly reported tick in Korea and Japan, but it is very rare in China. In this study, six I. nipponensis samples were collected from three black goats in Hunan province, China. Ticks identified morphologically as I. nipponensis were then examined by PCR with two different molecular markers: mitochondrial cox1 and the second internal transcribed spacer of ribosomal DNA genes. Sequence comparison and phylogenetic analysis of the cox1 sequences confirmed that all of the examined hard Ixodes ticks represented I. nipponensis. This finding indicates a potential risk of zoonotic I. nipponensis infection in humans and animals in China. To our knowledge, this is the first report documenting the occurrence of I. nipponensis infection in goats in China.

Proteomics analysis of faecal proteins in the tick Haemaphysalis flava

BACKGROUND

Ticks and tick-borne diseases are of major public health concern. Currently, development of vaccines against ticks is considered crucial for their control. A critical step in this process is the screening of viable antigens. Faeces are byproducts of digestion and blood meal utilization, and partly reflect the vitality and vector potential of ticks. However, an integrated analysis of proteins in tick faeces is lacking. The present study explored the protein components in the faeces of the tick Haemaphysalis flava, by liquid chromatography-tandem mass spectrometry (LC/MS-MS) to identify potential protein antigens for vaccine development against ticks.

METHODS

Faeces from adult H. flava engorged females were collected. Proteins were extracted from faeces, and the trypsin-digested peptides were analyzed by LC/MS-MS. High confidence proteins were identified based on unique peptides revealed by MS. Potential faecal protein genes, as well as their sources, were also characterized by searching previous transcriptome datasets from the salivary glands and midgut of H. flava.

RESULTS

In total, 21 were recognized with confidence. Amongst these, 18 were of likely tick origin, while three proteins (serum albumin, haemoglobin α and β subunits) were likely from hosts. Seventeen unigenes corresponding to these proteins were retrieved by searching our previous H. flava salivary glands and midgut transcriptomic datasets. Some proteins were reported to prevent blood clotting, play a role in immunity and antibiosis, and formation of musculature. The functions of the remaining proteins are unknown.

CONCLUSIONS

Identifying antigens for tick vaccine development is feasible by analyzing the faecal proteome as well as the transcriptomes of salivary glands and midguts. The vast number of proteins detected in tick faeces highlights the complexity of blood digestion in ticks, a field that needs more investigation.

Molecular characterization of hard tick Haemaphysalis longicornis from China by sequences of the internal transcribed spacers of ribosomal DNA

In the present study, the entire first and second internal transcribed spacer (ITS-1 and ITS-2) regions of nuclear ribosomal DNA (rDNA) of Haemaphysalis longicornis from China were amplified by polymerase chain reaction. The 45 representative amplicons were sequenced, and sequence variation in the ITS was examined. The ITS sequences of H. longicornis were 3644 bp in size, including the part of 18S rDNA, 28S rDNA sequences and the complete ITS-1, 5.8S rDNA and ITS-2 sequences. Sequence analysis revealed that the ITS-1, 5.8S rDNA and ITS-2 of this hard tick were 1582, 152, and 1610 bp in size, respectively. The intra-specific sequence variations of ITS-1 and ITS-2 within H. longicornis were 0-2 and 0-2.2%; however, the inter-specific sequence differences among members of the genus Haemaphysalis were significantly higher, being 35.1-55.2 and 37-52% for ITS-1 and ITS-2, respectively. The molecular approach employed in this study provides the foundation for further studies of the genetic variation of H. longicornis from different hosts and geographical origins in China.

Proteomic profiling of the midgut contents of Haemaphysalis flava

Scant information is available regarding the proteins involved in blood meal processing in ticks. Here, we aimed to highlight the midgut proteins involved in preventing blood meal coagulation, and in facilitating intracellular digestion in the tick Haemaphysalis flava. Proteins were extracted from the midgut contents of fully engorged and partially engorged ticks. We used liquid chromatography tandem-mass spectrometry (LC-MS/MS) analysis to identify 131 unique peptides, and 102 proteins. Of these, 15 proteins, each with at least two unique peptides, were recognized with high confidence. We also retrieved 18 unigenes from our previous published transcriptomic libraries of the midguts and salivary glands of H. flava, and inferred the primary structures of nine proteins and fragments of five proteins. There were 23 and 21 unique proteins in the midgut contents of fully engorged and partially engorged ticks, respectively. We detected 58 shared proteins in the midgut contents of both fully engorged and partially engorged ticks. Of these, seven were significantly differentially expressed between fully engorged and partially engorged ticks: actin, calmodulin, elongation factor-1α, hsp90, multifunctional chaperone, tubulin α, and tubulin β. Our results demonstrated that the proteome of the midgut contents, combined with the transcriptome of the midgut, was a viable method for the reinforcement of protein identification. This method will facilitate further study of blood meal processing by ticks, as well as the identification of clues for tick infestation control. The existence of numerous proteins detected in the midgut contents also highlight the complexity of blood digestion in ticks; this area is in need of further investigation.

Microbial population analysis of the midgut of Melophagus ovinus via high-throughput sequencing

Background

Melophagus ovinus, one of the most common haematophagous ectoparasites of sheep, can cause anaemia and reductions in weight gain, wool growth and hide value. However, no information is available about the microfloral structure of the midgut of this ectoparasite. In the present study, we investigated the microbial community structure of the midgut contents of fully engorged female and male M. ovinus using Illumina HiSeq.

Results

The phylum showing the highest abundance was Proteobacteria (99.9%). The dominant bacterial genera in females and males were Bartonella, Arsenophonus and Wolbachia. Some less abundant bacterial genera were also detected, including Enterobacter, Acinetobacter, Halomonas, Shewanella, Bacillus and Staphylococcus.

Conclusions

Bartonella, Arsenophonus and Wolbachia were the dominant bacterial genera in the midgut of female and male M. ovinus. Although detected, Enterobacter, Acinetobacter, Halomonas, Shewanella, Bacillus and Staphylococcus showed low abundances. Importantly, this is the first report of the presence of Arsenophonus, Wolbachia, Enterobacter, Halomonas, Shewanella, Bacillus and Staphylococcus in the midgut of M. ovinus.

PCR denaturing gradient gel electrophoresis as a useful method to identify of intestinal bacteria flora in Haemaphysalis flava ticks

Ticks are blood-sucking ectoparasites of great medical and veterinary significance that can transmit bacteria, protozoa, fungi and viruses, causing a variety of human and animal diseases worldwide. In the present study, the intestinal bacterial flora associated with Haemaphysalis flava ticks in different developmental stages were analyzed using polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE). Eleven distinct DGGE bands were found using PCR-DGGE method. Sequences analyses indicated that they belonged to Bacillus cereus, Candidatus rickettsia, Erwinia sp., Klebsiella pneumoniae, Pectobacterium carotovorum, Pseudomonas aeruginosa, Rickettsia peacockii, Rickettsia helvetica, Rickettsia slovaca, Staphylococcus simulans and Uncultured bacterium clone. Our find that the K. pneumoniae and P. aeruginosa isolates were presented in all H. flava ticks in different developmental stages. The present results indicated that zoonotic pathogens are present in H. flava ticks in Henan province, China. To our knowledge, this is the first report on intestinal bacterial flora associated with H. flava ticks in China.

Cloning and expression pattern of a heat shock cognate protein 70 gene in ticks (Haemaphysalis flava)

Ticks and tick-borne-diseases have serious public health implications, and screening feasible protein candidates for vaccines development is identified to be an effective alternative to control of tick infestations. In current study, we focused on cloning the full-length gene encoding a heat shock cognate protein 70 (Hsc70), a molecular chaperone of critical functional roles belonging to heat shock protein 70 (HSP70) family, in salivary glands of Haemaphysalis flava, namely Hf-Hsc70, and analyzing the expression of Hf-Hsc70 in different life phases, organs and ambient temperatures. Rapid amplification of cDNA ends (RACE) was performed to amplify the 5' and 3' ends of Hf-Hsc70. The expression profiles of Hf-Hsc70 were studied by semi-quantitative real-time PCR (RT-PCR). The full-length of Hf-Hsc70 was 2363 bp, and contained an ORF of 1965 bp encoding a protein of 648 amino acids. The expression levels of Hf-Hsc70 at different life phases were in the order of female larvae < female fully engorged nymphs < male adult ticks < female full engorged adult ticks < female half engorged adult ticks. The relative expression of Hf-Hsc70 in salivary glands was steadily higher than that in midguts (p < 0.05) regardless of feeding status. A 3-h of heat stress did not significantly induce the up-regulation of Hf-Hsc70 transcription. These results indicated that Hf-Hsc70 was a constitutive form of HSP70 family, and its expression pattern in different life phases and organs suggested a possible role in blood feeding, which would further make Hsc70 a potential candidate for the development of vaccines against ticks.

Comparative profiling of hepatopancreas transcriptomes in satiated and starving Pomacea canaliculata

Background

Although Pomacea canaliculata is native to South and Central America, it has become one of the most abundant invasive species worldwide and causes extensive damage to agriculture and horticulture. Conventional physical and chemical techniques have been used to eliminate P. canaliculata, but the effects are not ideal. Therefore, it is important to devise a new method based on a greater understanding of the biology of P. canaliculata. However, the molecular mechanisms underlying digestion and absorption in P. canaliculata are not well understood due to the lack of available genomic information for this species, particularly for digestive enzyme genes.

Results

In the present study, hepatopancreas transcriptome sequencing produced over 223 million high-quality reads, and a global de novo assembly generated a total of 87,766 unique transcripts (unigenes), of which 19,942 (22.7%) had significant similarities to proteins in the UniProt database. In addition, 296,675 annotated sequences were associated with Gene Ontology (GO) terms. A Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment was performed for the unique unigenes, and 262 pathways (p-value < 10⁻⁵) in P. canaliculata were found to be predominantly related to plant consumption and coarse fiber digestion and absorption. These transcripts were classified into four large categories: hydrolase, transferase, isomerase and cytochrome P450. The Reads Per Kilobase of transcript per Million mapped reads (RPKM) analysis showed that there were 523 down-regulated unigenes and 406 up-regulated unigenes in the starving apple snails compared with the satiated apple snails. Several important genes are associated with digestion and absorption in plants: endo-beta-1, 4-glucanase, xylanase, cellulase, cellulase EGX1, cellulase EGX3 and G-type lysozyme genes were identified. The qRT-PCR results confirmed that the expression patterns of these genes (except for the longipain gene) were consistent with the RNA-Seq results.

Conclusions

Our results provide a more comprehensive understanding of the molecular genes associated with hepatopancreas functioning. Differentially expressed genes corresponding to critical metabolic pathways were detected in the transcriptome of starving apple snails compared with satiated apple snails. In addition to the cellulase gene, other genes were identified that may be important factors in plant matter metabolism in P. canaliculata, and this information has the potential to expedite the study of digestive physiology in apple snails.

Electronic supplementary material

The online version of this article (doi:10.1186/s12863-017-0485-7) contains supplementary material, which is available to authorized users.

Genetic variation in mitochondrial genes of the tick Haemaphysalis flava collected from wild hedgehogs in China

The tick Haemaphysalis flava (Acari: Ixodidae) is an important ectoparasite, which causes direct damage to their hosts and also acts as a vector of various infectious disease agents in China. Despite its significance, the epidemiology, genetics and biology of H. flava has not been studied in detail. In the present study, the genetic variation in three mitochondrial (mt) DNA regions, namely cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 and 4 (nad1 and nad4), was examined in H. flava ticks collected from wild hedgehogs in China. A portion of cox1 (pcox1), nad1 (pnad1) and nad4 (pnad4) genes were PCR amplified from individual H. flava ticks and the amplicons were sequenced. The length of the sequences of pcox1, pnad1 and pnad4 were 849, 285 and 626 bp, respectively. The intra-specific sequence variation within H. flava was 0-0.4% for pcox1, 0-0.4% for pnad1 and 0-0.3% for pnad4. However, the inter-specific variation was significantly higher, 12.5-14.3%, 13.6-24.8% and 14.8-19% for pcox1, pnad1 and pnad4, respectively. Phylogenetic analysis based on Maximum likelihood (ML) method using the combined target mt gene sequences confirmed that all isolates of Haemaphysalis were H. flava. The molecular approach employed in this study provides a tool for further elucidating the molecular diversity of H. flava in China and elsewhere in Asia.

PCR-DGGE test for direct identification of intestinal bacterial flora in blood feeding ticks in China

Ticks are vectors of diseases that affect humans and animals worldwide. In current study, the intestinal bacterial flora associated with the blood feeding ticks (Haemaphysalis flava, Haemaphysalis longicornis, Rhipicephalus haemaphysaloides, Boophilus microplus and Dermacentor sinicus) were analyzed using polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) and then sequenced. The five ticks were collected from cattle, dog, hedgehog and goats in Fujian, Shandong, Henan, Jiangxi, Hunan, Shanxi and Guangxi provinces, China. Our results show that nine distinct DGGE bands were found using PCR-DGGE method. Sequences analyses indicated that they belonged to Rickettsia peacockii, Rickettsia raoultii, Rickettsia helvetica, Rickettsia slovaca, Rickettsia tarasevichiae, Coxiella sp., Erwinia sp., Klebsiella pneumoniae and Pseudomonas aeruginos. The present results indicate that zoonotic pathogens are present in ticks in many provinces of China. This useful information will aid in the epidemiology of tick-borne zoonotic diseases in China as well as in raising awareness to avoid tick bites is an important measure to prevent the infection and transmission of zoonotic pathogens.

Expression pattern of subA in different tissues and blood-feeding status in Haemaphysalis flava

Tick-borne-diseases (TBD) pose a huge threat to the health of both humans and animals worldwide. Tick vaccines constitute an attractive alternative for tick control, due to their cost-efficiency and environmental-friendliness. Subolesin, a protective antigen against ticks, is reported to be a promising candidate for the development of broad-spectrum vaccines. However, the entire length of its gene, subA, and its gene expression pattern in different tissues and blood-feeding status (or different levels of engorgement) have not been studied extensively. In our study, the full-length of subA in Haemaphysalis flava, Rhipicephalus haemaphysaloides, Rhipicephalus microplus, and Dermacentor sinicus was cloned by RACE-PCR. The subA expression pattern was analyzed further in H. flava in different tissues and blood-feeding status by RT-PCR. We found that the full-length of subA in H. flava, R. haemaphysaloides, R. microplus, and D. sinicus was 1318, 1498, 1316, and 1769 bp, respectively, with encoded proteins at 180, 162, 162, and 166 aa in length, respectively. The primary structure of subolesin in H. flava included three conserved regions and two hypervariable regions, with no signal peptide. SubA expression in female H. flava of different blood-feeding status was in the order of the fasted < the 1/4-engorged < the half-engorged < the fully-engorged (p < 0.01). Tissue expression of subA was in the order of salivary gland > midgut > integument (p < 0.01), but its expression in salivary glands was not statistically different from that in ovaries. We concluded that subolesin was a conserved antigen and that subA was expressed differentially in H. flava in different tissues and blood-feeding status. Those features made subolesin feasible as a potential target antigen for development of a universal vaccine for the control of tick infestations and a reduction in TBD.

Bacteriological analysis of saliva from partially or fully engorged female adult Rhipicephalus microplus by next-generation sequencing

Tick-borne diseases are a major epidemiological problem worldwide. The aim of this study was to investigate the bacterial composition of saliva obtained from engorged adult Rhipicephalus microplus females. Saliva samples collected from partially or fully engorged adult female ticks were analysed using an ultra-high-throughput Illumina HiSeq 2500 sequencing system. To elucidate the possible routes of bacterial transmission, the bacterial flora from whole ticks were also investigated. Proteobacteria, Firmicutes, and Actinobacteria were the predominant phyla in all samples, and Acinetobacter, Rickettsia, Escherichia and Coxiella were the major genera. Microbial diversity in saliva samples from partially engorged ticks was more complex than that of samples from fully engorged individuals. The comparison of saliva and whole-tick samples suggests that bacteria in saliva also colonize the tick's body. We believe that some bacterial genera, such as Dermacoccus, Achromia, SMB53, Sutterella, Providencia, Mycoplana, Oscillospira, and Agrobacterium, were found and reported in ticks for the first time. The Coxiella and Rickettsia detected in this study might be tick-borne pathogens, suggesting health risks associated with exposure to R. microplus in humans and animals. These findings may serve as the basis for developing strategies to control ticks and tick-borne diseases.

Enolase, a plasminogen receptor isolated from salivary gland transcriptome of the ixodid tick Haemaphysalis flava

Enolase, a multifunctional protein, is shown to act as a plasminogen receptor that contributes to fibrinolysis, which plays an important role in preventing the formation of blood clots during tick feeding. The study of enolase genes provides opportunities to develop a potential antigen target for tick control. So far, enolase has been identified in only a few species of ticks. Knowledge of the exact mechanisms of plasminogen activation and fibrinolysis by enolase as a plasminogen receptor is limited. Here, we cloned the enolase full-length complementary DNA (cDNA) from the salivary glands of Haemaphysalis flava, expressed it, and analyzed the function of the recombinant H. flava enolase. The enolase cDNA was 1988 bp in length and encoded 433 amino acid residues. It contained two domains and some highly conserved functional motifs including an assumed membrane re-association region "AAVPSGASTGI." The enolase exhibited 83.3 % amino acid similarity to that of the putative enolase of Ixodes ricinus, and 85 % to that of Ornithodoros moubata enolase. After eukaryotic expression in insect cells, Western blot analysis showed that the mouse antiserum against the hexahistidine-tagged recombinant enolase protein recognized a band of approximately 48 kDa. The recombinant enolase bound human plasminogen in a dose-dependent manner and enhanced plasminogen activation in the presence of host tissue plasminogen activator (t-PA), most probably to promote fibrinolysis and maintain blood flow at the host-tick interface. Real-time quantitative polymerase chain reaction (qPCR) analysis showed that the expression level of enolase in salivary glands was significantly higher than in other tested tissues. Although the enolase was expressed in all developmental stages, it had the highest expression in the rapid blood feeding period of ticks. These findings indicate that the enolase might play an important role in blood feeding of H. flava.

Identification of intestinal bacterial flora in Rhipicephalus microplus ticks by conventional methods and PCR-DGGE analysis

In this study, we have analyzed the intestinal microbial flora associated with Rhipicephalus microplus ticks using both culture-dependent and independent methods based on PCR and denaturing gradient gel electrophoresis (PCR-DGGE). The R. microplus ticks were collected from cattle and goats in Jiangxi, Hunan and Guizhou Provinces of China. Three distinct strains of bacteria were isolated using culture-dependent methods: Staphylococcus simulans, Bacillus subtilis and Bacillus flexus strain. Nineteen distinct DGGE bands were found using PCR-DGGE analysis, and their search for identity shows that they belonged to Rickettsiaceae, Xanthomonadaceae, Coxiella sp., Ehrlichia sp., Pseudomonas sp., Ehrlichia sp., Orphnebius sp., Rickettsia peacockii, Bacillus flexus. Rickettsia peacockii and Coxiella genus were the dominant strain of the R. microplus ticks from cattle, Pseudomonas sp. and B. flexus strain were the most common species in all tick samples from goats. Ehrlichia canis were detected only in R. microplus ticks from Yongshun area in Hunan Province. The results indicate that the intestinal microbial diversity of R. microplus ticks was influenced by tick hosts and local differences in the sampling location and these two aspects may affect transmission of pathogen to humans and animals.

De novo sequencing, assembly and analysis of salivary gland transcriptome of Haemaphysalis flava and identification of sialoprotein genes

Saliva plays an important role in feeding and pathogen transmission, identification and analysis of tick salivary gland (SG) proteins is considered as a hot spot in anti-tick researching area. Herein, we present the first description of SG transcriptome of Haemaphysalis flava using next-generation sequencing (NGS). A total of over 143 million high-quality reads were assembled into 54,357 unigenes, of which 20,145 (37.06%) had significant similarities to proteins in the Swiss-Prot database. 13,513 annotated sequences were associated with GO terms. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that 14,280 unigenes were assigned to 279 KEGG pathways in total. Reads per kb per million reads (RPKM) analysis showed that there were 3035 down-regulated unigenes and 2260 up-regulated unigenes in the engorged ticks (ET) compared with the semi-engorged one (SET). Several important genes are associated with blood feeding and ingestion as secreted salivary proteins, concluding cysteine, longipain, 4D8, calreticulin, metalloproteases, serine protease inhibitor, enolase, heat shock protein and AV422 in SG, were identified. The qRT-PCR results confirmed that patterns of these genes (except for the longipain gene) expression were consistent with RNA-seq results. This de novo assembly of SG transcriptome of H. flava not only provides more chance for screening and cloning functional genes, but also forms a solid basis for further insight into the changes of salivary proteins during blood-feeding.

Optimizing melphalan pharmacokinetics in regional melanoma therapy: does correcting for ideal body weight alter regional response or toxicity?

BACKGROUND

This study aims to determine what effect correcting melphalan dosing for ideal body weight (IBW) has on toxicity and response in isolated limb infusion (ILI) in patients with advanced extremity melanoma.

METHODS

This was an open observational study examining whether correcting the melphalan dose for IBW will influence response and toxicity in patients undergoing ILI for advanced extremity melanoma in 41 patients undergoing 42 procedures (13 without correction for IBW; and 29 with correction for IBW). Melphalan pharmacokinetics, limb toxicity, serologic toxicity, and response at 3 months were compared.

RESULTS

The corrected group had a lower estimated limb volume (V (esti)) to melphalan volume at steady state (V (ss)) (P < .0001) ratio as well as lower incidence of grade > or =3 regional toxicity, serologic toxicity, and compartment syndrome (P = .0249, P = .027, P = .02). There was a positive correlation of V (esti)/V (ss) to toxicity (P = .0127, r = .382). No significant difference in response (P = .3609) between the groups was found, although there was a trend of association between V (esti)/V (ss) and response (P = .051, r = .3383).

CONCLUSIONS

Correcting for IBW in ILI lowers toxicity without significantly altering response rates.

[Polymorphism in the partial mitochondrial nad4 gene of Schistosoma japonicum]

The partial NADH dehydrogenase subunit 4 (pnad4) fragment was amplified by polymerase chain reaction (PCR) from Schistosoma japonicum collected from 4 areas in Hunan province, and the amplicons were cloned and sequenced. A 480 bp sequence was obtained and the nucleotide difference between samples from the four locations were 0.4%-1.3%. Low level of sequence variability between and within different populations of S. japonicum was detected. The results are worthwhile for further study on the population genetic structures of S. japonicum.

The impact of the cigarette market opening in Taiwan

OBJECTIVE

To assess the effect of the opening of the Taiwanese cigarette market on cigarette consumption, changes in market share, and the effects on tobacco control efforts.

METHODS

With the use of key word "Taiwan", the Legacy Tobacco Documents Library of the University of California, San Francisco, was searched for internal documents related to smuggling activities, promotion of light cigarettes, and market share analyses in Taiwan. Age adjusted smoking rates and cigarette and betel quid consumption before and after market opening were compared.

RESULTS

By 2000, the market share of imported cigarettes increased from less than 2% in 1986 to nearly 50%, and per capita cigarette consumption increased 15% following market opening. Because of the sharp increase in smuggling, with contraband cigarettes being as popular as legal imports, and the rapid proliferation of retail outlets, such as betel quid stalls, the market penetration by foreign tobacco companies was greater in Taiwan than among the other Super 301 Asian countries. Aggressive cigarette marketing strategies were associated with a 6% increase in adult male smoking prevalence, and with a 13% increase in the youth rate, within three years after market opening. The market opening also had an incidental effect on increasing the popularity of betel quid. Betel quid chewing has since become a major public health problem in Taiwan.

CONCLUSION

The opening of the cigarette market in 1987 had a long lasting impact on Taiwan. It increased smoking prevalence and the market has become dominated by foreign companies. The seriousness of smuggling and its associated loss of revenue by the government, the extent of increased youth smoking and its associated future health care costs, and the increased use of betel quid and the associated doubling of oral cancer mortality rates each pose significant problems to Taiwan. However, the market opening galvanised anti-smoking sentiment and forced the government to initiate and intensify a series of tobacco control efforts.

Excess injury mortality among smokers: a neglected tobacco hazard

OBJECTIVE

To assess the mortality risks from injuries for smokers and ex-smokers and to quantify the mortality burden of smoking from injury in Taiwan.

METHODS

Smokers' (and ex-smokers') mortality risks from injuries were compared with that of non-smokers in a merged cohort from Taiwan. A total of 64,319 male subjects were followed up for 12-18 years. Relative risks (RR) (adjusted for age and alcohol use) and 95% confidence intervals (CI) for cause specific injury deaths were calculated using the Cox proportional hazard model. Relative risks of injury mortality were also calculated to assess the presence of dose-response relations with daily smoking quantity.

RESULTS

Alcohol use adjusted relative mortality risks for all injuries (RR 1.69, 95% CI 1.39 to 2.05) including those from motor vehicle accidents (RR 1.88, 95% CI 1.44 to 2.45) and non-motor vehicle accidents (RR 1.48, 95% CI 1.11 to 1.99) were significantly higher for smokers than non-smokers. Mortality was also increased for most subtypes of non-motor vehicle injuries including falls, fires, and job related injuries. Furthermore, these increases were dose dependent, with the heaviest smokers having the highest risk and the lightest smokers the lowest risk, and ex-smokers, no increase. In 2001, over one fifth (23%) of all male injury deaths in Taiwan was associated with smoking.

CONCLUSION

This study demonstrated the significant association between fatal injuries and smoking. This relation adds further weight to smoking cessation campaigns.

Workplace smoking related absenteeism and productivity costs in Taiwan

OBJECTIVE

To estimate productivity losses and financial costs to employers caused by cigarette smoking in the Taiwan workplace.

METHODS

The human capital approach was used to calculate lost productivity. Assuming the value of lost productivity was equal to the wage/salary rate and basing the calculations on smoking rate in the workforce, average days of absenteeism, average wage/salary rate, and increased risk and absenteeism among smokers obtained from earlier research, costs due to smoker absenteeism were estimated. Financial losses caused by passive smoking, smoking breaks, and occupational injuries were calculated.

RESULTS

Using a conservative estimate of excess absenteeism from work, male smokers took off an average of 4.36 sick days and male non-smokers took off an average of 3.30 sick days. Female smokers took off an average of 4.96 sick days and non-smoking females took off an average of 3.75 sick days. Excess absenteeism caused by employee smoking was estimated to cost USD 178 million per annum for males and USD 6 million for females at a total cost of USD 184 million per annum. The time men and women spent taking smoking breaks amounted to nine days per year and six days per year, respectively, resulting in reduced output productivity losses of USD 733 million. Increased sick leave costs due to passive smoking were approximately USD 81 million. Potential costs incurred from occupational injuries among smoking employees were estimated to be USD 34 million.

CONCLUSIONS

Financial costs caused by increased absenteeism and reduced productivity from employees who smoke are significant in Taiwan. Based on conservative estimates, total costs attributed to smoking in the workforce were approximately USD 1032 million.

Smoking attributable mortality for Taiwan and its projection to 2020 under different smoking scenarios

OBJECTIVES

To estimate smoking attributable mortality (SAM) in Taiwan for the years 2001 through 2020 under scenarios of reductions in smoking rates by 0%, 2%, 4%, and 10% per year.

METHOD

The smoking attributable fraction (SAF) was used to calculate SAM from the risk experience in following up a large cohort (86 580 people) in Taiwan. Smoking rates were based on the 2001 National Health Interview Survey and other national surveys. An average 10 year lag was assumed between smoking rates and subsequent mortality.

RESULTS

In 2001, 18 803 deaths, or 1 out of 4 deaths (27%), in middle aged men (35-69 years old) were attributable to smoking. SAM has been increasing and will continue to increase if smoking rates remain constant or even if reduced annually by 2%. SAM would begin to decrease only if rates were to be reduced by at least 4% a year.

CONCLUSIONS

The projected SAM in this study illustrates the seriousness of smoking caused mortality. Current efforts in tobacco control would lead to a progressive increase in SAM, unless efforts were doubled and smoking rates reduced by more than 4% a year. The urgency in requiring stronger tobacco control programmes to attenuate the staggering death tolls is compelling.

Reducing health disparity in Taiwan: quantifying the role of smoking

OBJECTIVE

To assess the impact of smoking disparities on health disparities, in terms of gap in life expectancy, in Taiwan cities and counties.

METHODS

Using the decomposition method of life expectancy, the contribution of each disease category to the life expectancy gap was quantitatively expressed as the number of years of life. The smoking attributable fraction (SAF) was calculated for each city and county based on their respective smoking prevalence and relative risk for each smoking related disease. The smoking attributable gap (SAG) in life expectancy between two sites is the sum of the difference in SAF between two sites for each smoking related disease multiplied by the number of years this disease contributed to the life expectancy gap.

RESULTS

Significant health and smoking disparities were present among the 23 cities and counties in Taiwan. These health disparities and smoking disparities were highly correlated (R2 = 0.3676). Generally, the health gap increased with increasing smoking disparity. The disparity in smoking prevalence and intensity among cities and counties in Taiwan was responsible for up to 19% of the health disparity. The health disparity is also highly correlated (R2 = 0.3745) with SAG in life expectancy.

CONCLUSIONS

Reducing smoking is important to health, and reducing the smoking disparity is also important for reducing the health disparity observed in Taiwan. The larger the health disparity is, the more important the smoking attributable disparity could be. The reduction of smoking disparities could be a realistic and cost effective way toward reducing health disparities.

Role of parents and peers in influencing the smoking status of high school students in Taiwan

OBJECTIVES

To assess parental influence on smoking behaviour by high school students in an Asian culture and to compare the relative importance of parental and peer influence.

METHODS

A 5% nationally representative sample, including 44 976 high school students in 10th to 12th grade (aged 15-18 years) in Taiwan, were surveyed in 1995. Each completed a long self administered questionnaire. Parental influence was measured by examining both parental behaviour (smoking status) and attitudes (perceived "tender loving care" (TLC) by adolescents). Changes in smoking status were used to determine peer influence, defined as the increase in the likelihood of smoking from grade 10 to 12 in a steady state environment. Odds ratios (ORs) were calculated for parental and peer influence, using logistic regression.

RESULTS

Adolescents of smoking parents with low TLC had the highest smoking rates and those of non-smoking parents with high TLC had the lowest. The difference was more than twofold in boys and more than fourfold in girls. When either parental smoking status or TLC alone was considered, parental influence was similar to peer influence in boys, but larger than peer influence in girls. However, when smoking status and TLC were considered jointly, it became larger than peer influence for both groups (OR 2.8 v 1.8 for boys and OR 3.9 v 1.3 for girls).

CONCLUSION

When parental influence is taken as parental behaviour and attitude together, it plays a more important role than peer influence in smoking among high school students in Taiwan. This study, characterising such relationships among Asian populations for the first time, implies that future prevention programmes should direct more efforts toward the parental smoking and parent-child relationships, and not aim exclusively at adolescents in schools.

Are marketing campaigns in Taiwan by foreign tobacco companies targeting young smokers?

OBJECTIVE

To assess the impact of promotions on cigarette sales in Taiwan after the cigarette market opened to foreign companies, and to assess whether young smokers were targeted by these companies.

METHODS

Trends in cigarette sales, advertising expenditure, brand preference, and cigarette consumption were examined for the period following the 1987 opening of the cigarette market. Tobacco industry internal documents from Legacy Tobacco Documents Library of the University of California, San Francisco, were searched for corporate strategies on promoting youth consumption in Taiwan.

RESULTS

Between 1995 and 2000, the inflation adjusted advertising expenditures by all foreign firms increased fourfold. Much of the expenditure was spent on brand stretching the Mild Seven (Japan) and Davidoff (Germany) brands in television advertising. By 2000, the market share of foreign cigarettes exceeded domestics by three to one among young smokers and the leading brand preferred by this segment shifted from the most popular domestic brand (Long Life) to a foreign brand (Mild Seven). Furthermore, there was a sudden increase of 16.4% in smoking rates among young adults (from 36.1% to 42.0%) during the first five years after the market opened. This was also accompanied by increased per capita cigarette consumption and decreased age of smoking initiation. Industry documents confirmed the use of strategies targeted at the young. In particular, establishing new point of sale (POS) retail stores or promotional activities at POS were found to be more effective than advertising in magazines.

CONCLUSIONS

This study provides evidence that advertising increased with increased competition following the market opening, which, in turn, spurred cigarette sales and consumption. Foreign tobacco companies have deliberately targeted youth in Taiwan and succeeded in gaining three quarters of their cigarette purchases within a decade. Expanding youth consumption will incur excessive future health care costs borne by society. Foreign tobacco companies should be obligated to reimburse these expenses through higher tariffs on cigarettes.

Uncovering the relation between betel quid chewing and cigarette smoking in Taiwan

OBJECTIVE

To describe the characteristics of betel quid chewers and to investigate the behavioural and mortality relations between betel quid chewing and cigarette smoking.

METHOD

Prevalence and mortality risks of betel quid chewers by smoking status were calculated, based on the National Health Interview Survey in 2001 and a community based cohort, respectively. Cox's proportional hazards model was used to adjust mortality risks for age, alcohol use, and education.

RESULTS

Almost all betel quid chewers were smokers, and most started chewing after smoking. Chewers were predominantly male, mostly in their 30s and 40s, more likely being among the lowest educational or income group, and residing in the eastern regions of Taiwan. On average, betel quid chewers who smoked consumed 18 pieces of betel quid a day, and smoked more cigarettes per day. Far more smokers use betel quid than non-smokers (27.5% v 2.5%), but ex-smokers quit betel quid more than smokers (15.1% v 6.8%). The significantly increased mortality of betel quid users who also smoked, for all causes, all cancer, oral cancer, and cancer of the nasopharynx, lung, and liver, was the result of the combined effects of chewing and smoking. Smokers who chewed betel quid nearly tripled their oral cancer risks from a relative risk of 2.1 to 5.9. Increasing the number of cigarettes smoked among betel quid chewers was associated with a synergistic effect, reflective of the significant interaction between the two.

CONCLUSION

To a large extent, the serious health consequences suffered by betel quid chewers were the result of the combined effects of smoking and chewing. Betel quid chewing should not be considered as an isolated issue, but should be viewed conjointly with cigarette smoking. Reducing cigarette smoking serves as an important first step in reducing betel quid chewing, and incorporating betel quid control into tobacco control may provide a new paradigm to attenuate the explosive increase in betel quid use in Taiwan.

The health benefits of smoking cessation for adult smokers and for pregnant women in Taiwan

OBJECTIVE

To assess the benefits of smoking cessation regarding mortality reduction after smokers quit, and regarding the health of newborns after smoking mothers quit.

METHODS

Relative mortality risks (RR) for smokers aged 35 or older who quit years ago were calculated from the follow up of 71 361 civil servants and teachers recruited since 1989. Data from the Pregnancy Risk Assessment Monitoring System in Taipei City were used to calculate the odds ratios of body weights of newborns born to mothers of different smoking status.

RESULTS

Mortality risk for ex-smokers was significantly lower than that of current smokers for all causes (18%), all cancer (22%), lung cancer (39%), and ischaemic heart disease (54%). These benefits were not distinguishable initially, up to five years, but by year 17 and thereafter, substantial benefits of cessation accrued. Two thirds of smoking women quit during the first trimester of pregnancy, and only 2.2% of mothers smoked throughout pregnancy. The newborns from smoking mothers were smaller than those from never smoking mothers, but, if these mothers quit early in the first trimester, birth weights were normal.

CONCLUSIONS

The health benefits of smoking cessation, rarely reported for Asian populations, have been largely ignored by smokers in Taiwan, where cessation activities have been extremely limited. Findings of this study that risks from smoking can be attenuated or reversed should be widely communicated to motivate smokers to quit. Smokers should quit early, including smoking mothers, and not wait till medical conditions surfaced, to have the maximal benefits of cessation.

Smoking attributable medical expenditures, years of potential life lost, and the cost of premature death in Taiwan

OBJECTIVE

To estimate the smoking attributable medical expenditures and productivity loss of people aged 35 and over in Taiwan in 2001 from a societal viewpoint.

METHODS

A prevalence based approach was used to estimate smoking attributable costs. Epidemiological parameters were obtained from two follow up studies and government statistics. Data on medical care utilisation and expenditure were extracted from the National Health Insurance claim data.

RESULTS

Total smoking attributable medical expenditures (SAEs) amounted to USD 397.6 million, which accounted for 6.8% of the total medical expenditures for people aged 35 and over. Mean annual medical expenditures per smoker was USD 70 more than that of each non-smoker. Smoking attributable years of potential life lost (YPLL) totalled to 217,761 years for males and 15,462 years for females, and the corresponding productivity loss was USD 1371 million for males and USD 18.7 million for females.

CONCLUSION

Medical expenditures attributable to smoking accounted for 6.8% of the total medical expenditure of people aged 35 and over for the year 2001 in Taiwan. Corresponding YPLL and productivity loss also demand that actions be taken to fight cigarette smoking.