Human impact on the diversity and virulence of the ubiquitous zoonotic parasite Toxoplasma gondii.

A majority of emerging infectious diseases in humans are zoonoses. Understanding factors that influence the emergence and transmission of zoonoses is pivotal for their prevention and control. Toxoplasma gondii is one of the most widespread zoonotic pathogens known today. Whereas only a few genotypes of T. gondii dominate in the Northern Hemisphere, many genotypes coexist in South America. Furthermore, T. gondii strains from South America are more likely to be virulent than those from the Northern Hemisphere. However, it is not clear what factor(s) shaped modern-day genetic diversity and virulence of T. gondii Here, our analysis suggests that the rise and expansion of farming in the past 11,000 years established the domestic cat/mouse transmission cycle for T. gondii, which has undoubtedly played a significant role in the selection of certain linages of T. gondii Our mathematical simulations showed that within the domestic transmission cycle, intermediately mouse-virulent T. gondii genotypes have an adaptive advantage and eventually become dominant due to a balance between lower host mortality and the ability to superinfect mice previously infected with a less virulent T. gondii strain. Our analysis of the global type II lineage of T. gondii suggests its Old World origin but recent expansion in North America, which is likely the consequence of global human migration and trading. These results have significant implications concerning transmission and evolution of zoonotic pathogens in the rapidly expanding anthropized environment demanded by rapid growth of the human population and intensive international trading at present and in the future.

Molecular Detection, Multilocus Genotyping, and Population Genetics of Enterocytozoon bieneusi in Pigs in Southeastern China.

Enterocytozoon bieneusi is an important opportunistic pathogen widely distributed in humans and animals that causes diarrhea or fatal diarrhea in immunocompromised hosts. To examine the infection status and molecular characteristics of E. bieneusi in pigs, 725 fecal samples were collected from pigs in six areas of Fujian Province. The E. bieneusi genotypes were identified based on the internal transcribed spacer (ITS) regions of the ribosomal RNA (rRNA) gene by nested PCR, and its population genetics were analyzed by multilocus sequence typing (MLST). The results showed that the infection rate of E. bieneusi was 24.4% (177/725), and 11 known genotypes (EbpC, EbpA, CHN-RR2, KIN-1, CHG7, CHS5, CM11, CHG23, G, PigEBITS, and D) and 2 novel genotypes (FJF and FJS) were identified. All the genotypes were found to be clustered into zoonotic Group 1. Moreover, 52 positive samples were successfully amplified at minisatellite and microsatellite loci and formed 48 distinct multilocus genotypes (MLGs). Further population structure analyses showed strong genetic linkage disequilibrium (LD) and several recombination events (Rm), indicating that E. bieneusi has a clonal population structure. This study is the first to investigate the prevalence and molecular characteristics of E. bieneusi in Fujian Province and could provide baseline data to control E. bieneusi infection in pigs and humans and deepen our understanding of the zoonotic risk of E. bieneusi and its distribution in China.

Prevalence of gastrointestinal parasites in free-range yaks (Bos grunniens) in Gansu Province, Northwest China.

BACKGROUND: Little information about the prevalence of gastrointestinal parasites in yaks (Bos grunniens) in northwest China is available. Therefore, the objective of the study was to quantify faecal egg counts of gastrointestinal parasites (helminths and coccidia) in free-range yaks from Gannan Tibetan Autonomous Prefecture, Gansu Province, Northwest China. RESULTS: Parasites were detected in 290 of 733 (39.56%) faecal samples. The results showed that Strongylidae, Trichuris spp. and Eimeria spp. were detected all year round, Strongyloides papillosus was detected in autumn and summer, and Nematodirus spp. was detected in both autumn and spring. In contrast, Fasciola spp. was only detected in spring. The prevalence rates of parasitic infections in different seasons were significantly different. CONCLUSIONS: To our knowledge, this is the first investigation of gastrointestinal parasites in yaks (Bos grunniens) in Gansu, China. The results demonstrated a high prevalence of gastrointestinal parasitic infections, specifically GN infections, in yaks in GTAP and these infections can cause economic losses to the local cattle industry.

Occurrence of Enterocytozoon bieneusi in Chinese Tan sheep in the Ningxia Hui Autonomous Region, China.

Enterocytozoon bieneusi is a zoonotic parasite which is considered to be an opportunistic pathogen of humans and animals. A number of studies have reported E. bieneusi infection in various animals. However, no information is available on the occurrence of E. bieneusi in Tan sheep, a unique indigenous sheep species in the Ningxia Hui Autonomous Region, China. The objectives of the present study were to examine the prevalence and identify the genotypes of E. bieneusi in Tan sheep in China. A total of 1014 fecal specimens of Tan sheep from six farms in the Ningxia Hui Autonomous Region were examined by nested PCR amplification of the internal transcribed spacer (ITS) of nuclear ribosomal DNA. The total prevalence of E. bieneusi was 12.2% (124/1014), ranging from 0.5 to 22.2% on six farms. Sequence analysis identified 10 genotypes of E. bieneusi, including three known genotypes, BEB6, COS-I, and CHG13, and seven novel genotypes designated as NX1 to NX7, which all belonged to group 2 by phylogenetic analysis. This is the first report describing the prevalence of E. bieneusi in Tan sheep, and the new genotypes identified in the current study expand the genotype distribution of E. bieneusi. These findings provide baseline data and have implications for the epidemiology and control of E. bieneusi infection in Tan sheep.

Characterization of the complete mitochondrial genome of Marshallagia marshalli and phylogenetic implications for the superfamily Trichostrongyloidea.

Marshallagia marshalli (Nematoda: Trichostrongylidae) infection can lead to serious parasitic gastroenteritis in sheep, goat, and wild ruminant, causing significant socioeconomic losses worldwide. Up to now, the study concerning the molecular biology of M. marshalli is limited. Herein, we sequenced the complete mitochondrial (mt) genome of M. marshalli and examined its phylogenetic relationship with selected members of the superfamily Trichostrongyloidea using Bayesian inference (BI) based on concatenated mt amino acid sequence datasets. The complete mt genome sequence of M. marshalli is 13,891 bp, including 12 protein-coding genes, 22 transfer RNA genes, and 2 ribosomal RNA genes. All protein-coding genes are transcribed in the same direction. Phylogenetic analyses based on concatenated amino acid sequences of the 12 protein-coding genes supported the monophylies of the families Haemonchidae, Molineidae, and Dictyocaulidae with strong statistical support, but rejected the monophyly of the family Trichostrongylidae. The determination of the complete mt genome sequence of M. marshalli provides novel genetic markers for studying the systematics, population genetics, and molecular epidemiology of M. marshalli and its congeners.

Seroprevalence and Risk Factors of Fascioliasis in Yaks, Bos grunniens, from Three Counties of Gansu Province, China.

The aim of this study was to determine the seroprevalence and risk factors of fascioliasis in yaks, Bos grunniens, from 3 counties of Gansu Province in China. A total of 1,584 serum samples, including 974 samples from white yaks from Tianzhu, 464 from black yaks from Maqu, and 146 from black yaks from Luqu County, were collected and analyzed using ELISA to detect IgG antibodies against Fasciola hepatica. The overall F. hepatica seroprevalence was 28.7% (454/1,584), with 29.2% in white yaks (284/974) and 27.9% in black yaks (170/610). The seroprevalence of F. hepatica in yaks from Tianzhu, Luqu, and Maqu was 29.2%, 22.6%, and 29.5%, respectively. Female yaks (30.9%) had higher F. hepatica seroprevalence than male yaks (23.4%). Also, F. hepatica seroprevalence varied by different age group from 24.1% to 33.8%. Further, the seroprevalence ranged from 21.8% to 39.1% over different seasons. Interestingly, the season and age of yaks were associated with F. hepatica infection in yaks in the investigated areas. These findings provided a basis for further studies on this disease in yaks from 3 counties of Gansu Province in northwestern China, which may ultimately support the development of effective control strategies of fascioliasis in these areas.

Prevalence, Risk Factors and Multilocus Genotyping of Giardia intestinalis in Dairy Cattle, Northwest China.

Giardia intestinalis is a cosmopolitan protozoan parasite that can infect a range of animals, including dairy cattle. As information regarding the prevalence and genotyping of G. intestinalis infection in dairy cattle in northwestern China is limited, 2,945 feces samples from 1,224 dairy cattle in Gansu Province and from 1,614 in Ningxia Hui Autonomous Region (NXHAR) were examined between December 2012 and March 2014. The overall prevalence of G. intestinalis was 3.63% (107/2,945), with 2.63% and 4.38% in Gansu and NXHAR, respectively. Logistic regression analysis showed region, age and season to be significant risk factors for G. intestinalis infection. Assemblage analysis identified 106 assemblage E and one assemblage A at the triose phosphate isomerase (tpi) locus in this study. Intravariations were also detected at tpi, glutamate dehydrogenase (gdh) and beta giardin (bg) loci within assemblage E, showing seven, three, and five new subtypes, respectively. Moreover, 13 new multilocus genotypes (E20-E32) were observed in assemblage E. Effective strategies and measures should be taken to prevent and control giardiasis in Gansu and NXHAR.

Protective efficacy of pVAX-RON5p against acute and chronic infections of Toxoplasma gondii in BALB/c mice.

Toxoplasma gondii can infect all the warm-blooded animals and humans and causes serious diseases especially in immuno-compromised patients and pregnant women. Rhoptry neck proteins (RONs) play an important role in the formation of moving junction, which mediates the invasion of this parasite. A recombinant plasmid pVAX-RON5p, which can express part of RON5 protein in the eukaryocyte, was generated and used to immune BALB/c mice for evaluating the protective efficacy against the acute and chronic infections of T. gondii. Both humoral and cellular immune responses were evoked in mice by pVAX-RON5p immunization, and a slightly prolonged survival period was detected in the immunized group (7.6 ± 3.31 days) compared to the blank control (4.9 ± 0.32 days) after acute T. gondii infection (P < 0.05). For chronic infection of T. gondii, the number of cysts in the brain of pVAX-RON5p-immunized mice decreased 25.8% compared to blank control (P < 0.05). Our data suggested that RON5p DNA vaccine can induce partial protective immunity against acute and chronic T. gondii infections.

Transcriptomic analysis of global changes in cytokine expression in mouse spleens following acute Toxoplasma gondii infection.

Toxoplasma gondii is a global pathogen that infects a wide range of animals and humans. During T. gondii infection, the spleen plays an important role in coordinating the adaptive and innate immune responses. However, there is little information regarding the changes in global gene expression within the spleen following T. gondii infection. To address this gap in knowledge, we examined the transcriptome of the mouse spleen following T. gondii infection. We observed differential expression of 2310 transcripts under these conditions. Analysis of KEGG and GO enrichment indicated that T. gondii alters multiple immune signaling cascades. Most of differentially expressed GO terms and pathways were downregulated, while immune-related GO terms and pathways were upregulated with response to T. gondii infection in mouse spleen. Most cytokines were upregulated in infected spleens, and all differentially expressed chemokines were upregulated which enhanced the immune cells chemotaxis to promote recruitment of immune cells, such as neutrophils, eosinophils, monocytes, dendritic cells, macrophages, NK cells, basophils, B cells, and T cells. Although IFN-γ-induced IDO (Ido1) was upregulated in the present study, it may not contribute a lot to the control of T. gondii because most differentially expressed genes involved in tryptophan metabolism pathway were downregulated. Innate immunity pathways, including cytosolic nucleic acid sensing pathway and C-type lectins-Syk-Card9 signaling pathways, were upregulated. We believe our study is the first comprehensive attempt to define the host transcriptional response to T. gondii infection in the mouse spleen.

Recombinase polymerase amplification (RPA) combined with lateral flow (LF) strip for equipment-free detection of Cryptosporidium spp. oocysts in dairy cattle feces.

Cryptosporidium is a widespread protozoan parasite that infects a large number of vertebrate animals, resulting in varying degrees of diarrhea or even death. As dairy cattle feces is an important source of Cryptosporidium spp. infection, development of a handy and accurate detection method via its oocysts in dairy cattle feces would be interesting and necessary. We herein developed a quick detecting method using recombinase polymerase amplification (RPA) combined with lateral flow (LF) strip to detect DNA of Cryptosporidium oocysts in dairy cattle feces. The DNA was released by boiled water with 0.1 % N-lauroylsarcosine sodium salt (LSS). The established method was proven to be of higher sensitivity than normal polymerase chain reaction (PCR) amplification with the lowest detection of 0.5 oocyst per reaction, and specificity with no cross reactivity to other common protozoan species in the intestine of dairy cattle. The diagnostic method established herein is simple, rapid, and cost-effective, and has potential for further development as a diagnostic kit for the diagnosis of cryptosporidiosis of dairy cattle.

Seroprevalence and risk factors of bovine viral diarrhoea virus (BVDV) infection in yaks (Bos grunniens) in northwest China.

Bovine viral diarrhoea virus (BVDV), a member of the Pestivirus genus, is an important pathogen of cattle worldwide, causing reproductive disorders in adult cattle and mucosal disease in calves. However, limited information about BVDV infection in yaks (Bos grunniens) in China is available, especially in white yaks which is a unique yak breed that only lives in Tianzhu Tibetan Autonomous County (TTAC), Gansu Province, northwest China. Therefore, we conducted a cross-sectional study to estimate the seroprevalence and risk factors associated with BVDV infection in 1584 yaks in Gansu province, northwest China, between April 2013 and March 2014 using an indirect ELISA test. The overall seroprevalence of BVDV in yaks was 37.56 % (595/1584), with 45.08 % (275/610) in black yaks and 32.85 % (320/974) in white yaks. Moreover, positive yaks were found in all four regions, varied from 33.22 to 40.31 %. Male yaks had a similar seroprevalence (37.84 %) with that of the female yaks (37.11 %). Season, species and geographical origins of yaks were considered as risk factors analyzed by logistic regression model. To our knowledge, this is the first report of seroprevalence and risk factors associated with BVDV infection in white yaks in China.

Detection prevalence of H5N1 avian influenza virus among stray cats in eastern China.

Since 1997, more and more cases of the infectious H5N1 avian influenza virus (AIV) in humans have been reported all over the world but the transmission of H5N1 avian influenza virus to stray cats has been little demonstrated. The objective of this pilot investigation was to determine the prevalence of H5N1 AIV antibodies in stray cats in eastern China where is the dominant enzootic H5N1 highly pathogenic avian influenza virus (HP AIV). A total of 1,020 nasal swab and 1,020 serum samples were collected and tested. Evidence of HPAI H5N1 virus antibodies was present in two of the 1,020 serum samples that were positive by HI assay and NT assay, respectively. The results imply little transmission and that the Clade 2.3.2 HPAIV H5N1 infections in poultry did not significantly affect the rural animal shelters or suburban environment in eastern China. In future studies, these results can be used as baseline seroepidemiological levels for H5N1 AIV among cats in China.

The first lack of evidence of H7N9 avian influenza virus infections among pigs in Eastern China.

In this study, we sought to examine whether evidence existed suggesting that pigs were being infected with the novel H7N9 avian influenza virus. From November 2012 to November 2013, blood was drawn from 1560 pigs from 100 large farms in 4 provinces of eastern China. Many of these pigs were in close proximity to wild birds or poultry. Swine sera were studied using hemagglutinin inhibition (HI) assays and enzyme-linked immunosorbent assays (ELISAs) against the H7 antigen derived from the emergent H7N9 avian influenza virus (AIV). Only 29 of the 1560 samples had HI titers of 1:20 when using the H7N9 AIV antigens, and none of the 29 (H7N9 AIV) HI-positive samples were positive when using ELISA, indicating that no samples were positive for H7N9. The negative results were also verified using a novel competitive HA-ELISA. As pigs have been shown to be infected with other avian influenza viruses and as the prevalence of novel influenza A viruses (e.g., H7N9 AIV) may be increasing among poultry in China, similar seroepidemiological studies of pigs should be periodically conducted in the future.

Variant RONΔ160 of the RON receptor tyrosine kinase promotes the growth and invasion in vitro and in vivo in gastric cancer cell lines.

BACKGROUND: Recepteur d'origine nantais (RON) is a receptor tyrosine kinase whose overexpression has been observed in human gastric cancers. This study aimed to determine whether overexpression of the variant RONΔ160 could induce tumorigenicity of gastric cancer cells in vitro or in vivo, and whether its specific small molecule inhibitor (Compound I) could inhibit the effect of RONΔ160. METHODS: We constructed human gastric cancer cell line MGC-803 that was stably transfected with a recombinant plasmid expressing RONΔ160, and the effect of RONΔ160 overexpression and macrophage-stimulating protein (MSP) activation on proliferation, migration and invasion abilities of MGC-803 cells were evaluated. Tumor-bearing mice with gastric cancer cells were used to analyze the effects of RONΔ160 overexpression and Compound I on implanted tumor growth. RESULTS: In vitro, overexpression of RONΔ160 in MGC-803 cells resulted changes to their cell morphology, and promoted cell proliferation, migration and invasion. In addition, overexpression of RONΔ160 increased the proportion of cells in the S phase. The effect of RONΔ160 was significantly enhanced by induction of MSP inducing (p < 0.05). In vivo, RONΔ160 promoted the growth of MGC-803 cells in nude mice, including increased tumor size and weight, and lower tumor incubation period. The Compound I inhibited the tumorigenic abilities of RONΔ160 (p <0.05). CONCLUSIONS: The results indicate that overexpression of the variant RONΔ160 altered the phenotype and tumorigenicity of MGC-803 cells. Its specific small molecule inhibitor could inhibit the effect of RONΔ160. Therefore, the variant RONΔ160 may become a potential therapeutic target for gastric cancer.

Seroprevalence and risk factors of Toxoplasma gondii in Tibetan Sheep in Gansu province, Northwestern China.

BACKGROUND: Toxoplasma gondii, a protozoan parasite, infects almost all warm-blooded animals and humans. Limited information is available about T. gondii infection in Tibetan Sheep in Gansu province, northwestern China. In the present study, we estimated the seroprevalence and risk factors of T. gondii infection in this region of China. RESULTS: A total of 1732 Tibetan Sheep were included from Tianzhu and Maqu in Gansu province. Antibodies to T. gondii were examined by modified agglutination test (MAT), and 352 (20.3%) out of 1732 Tibetan sheep were found positive. Multivariate logistic regression analysis was used to analyze the risk factors associated with seroprevalence, the results showed that age, gender, and numbers of past pregnancies were not the significant risk factors. However, Tibetan sheep in Maqu had a 1.64 times (odds ratio [OR] =1.637, 95% CI =1.291-2.075, P < 0.001) higher seroprevalence compared to Tianzhu, and the seropositivity in summer were 1.61 times (OR =1.608, 95% CI =1.122-2.303, P = 0.010) higher compared to Tibetan sheep in winter, followed by 1.42 times (OR =1.419, 95% CI =1.002-2.011, P = 0.049) in spring. Thus, season and location were considered as risk factors associated with T. gondii infection in this study. CONCLUSIONS: This is the first report of T. gondii seroprevalence in Tibetan sheep in Gansu province, which enriches the epidemiological data of T. gondii infection in Tibetan sheep in China. The results of this study indicate that Tibetan sheep in Gansu province are frequently exposed to T. gondii, posing a direct threat to the public health as well as to local sheep industry. These data is useful to strengthen future prevention and control of T. gondii infection in Tibetan sheep in this region.

Seroprevalence and risk factors of Chlamydia abortus infection in free-ranging white yaks in China.

BACKGROUND: Chlamydia is gram-negative obligate bacteria which causes a wide variety of diseases in humans and animals. To date, there are a few reports about the seroprevalence of Chlamydia and the risk factors associated with Chlamydia infection in yaks in the world. In this study, 974 blood samples were collected from white yaks (Bos grunniens) in Tianzhu Tibetan Autonomous County, Gansu province, northwest China from June 2013 to April 2014. RESULTS: Antibodies against Chlamydia abortus were examined by the indirect hemagglutination (IHA) test, and 158 of 974 (16.22%) white yaks were seropositive for C. abortus antibodies at the cut-off of 1:16. The risk factors associated with seroprevalence were evaluated by a multivariate logistic regression analysis. Region, gender and age of white yak were left out of the final model, due to its insignificance in the logistic regression analysis (P > 0.05). However, season was considered as a major risk factor associated with C. abortus infection in white yaks. CONCLUSIONS: To our knowledge, this is the first survey of C. abortus seroprevalence in white yaks in China, which extends the host range for C. abortus and has important implications for public health and the local Tibetan economy.

Prevalence and molecular characterization of Cryptosporidium spp. in dairy cattle, northwest China.

Cryptosporidium spp. cause enteric diseases in a wide range of animals, including dairy cattle. However, limited information is available regarding prevalence and molecular characterization of Cryptosporidium spp. in dairy cattle in Gansu province and Ningxia Hui Autonomous Region (NXHAR), northwest China. A total of 2945 dairy feces samples (1257 from Gansu province and 1688 from NXHAR) were collected between December 2012 and March 2014 and were tested by PCR amplification of the small subunit (SSU) rRNA gene. A total of 150 (5.09 %, 58 from Gansu and 92 from NXHAR) samples were PCR-positive for Cryptosporidium, and the prevalence is associated with the region and age of dairy cattle. Species identification showed Cryptosporidium andersoni in 36 samples (24.00 %, 19 from NXHAR and 17 from Gansu), Cryptosporidium ryanae in 24 samples (16.00 %, 13 from NXHAR and 11 from Gansu), Cryptosporidium bovis in 70 samples (46.67 %, 41 from NXHAR and 29 from Gansu), and Cryptosporidium parvum in 20 samples (13.33 %, 19 from NXHAR and 1 from Gansu). A DNA sequence analysis of the gp60 gene suggested that all the 20 C. parvum isolates represented subtype IIdA15G1. These findings indicated the presence of zoonotic Cryptosporidium in Gansu and NXHAR. This is the first report of four species of Cryptosporidium (C. andersoni, C. ryanae, C. bovis, and C. parvum) infection in dairy cattle in Gansu province. This is also the first report of C. ryanae infection in dairy cattle in NXHAR. Effective control strategies should be implemented to prevent and control Cryptosporidium infection in dairy cattle and humans.

[Recombinase Polymerase Amplification and its Applications in Parasite Detection].

Recombinase polymerase amplification (RPA) is a recently -developed isothermal nucleic-acid-amplification technology that is based on the nucleic acid replication mechanism in T4 bacteriophage. With this technique, nucleic-acid templates can be amplified to measurable levels within 20 min at 37-42 °C. The. RPA process has high sensitivity and specificity, and is simple to operate, thus nucleic acids can be detected rapidly in non-laboratory conditions. Since its development in 2006, the RPA technique has been applied in agriculture, food safety, medicine, transgene detection, etc. In this review, we will give an overview on the research progress of RPA and its application in parasite detection.

Comparative proteomic analysis of different Toxoplasma gondii genotypes by two-dimensional fluorescence difference gel electrophoresis combined with mass spectrometry.

Toxoplasma gondii is a protozoan parasite infecting almost all warm-blooded animals and humans. There are three infective stages of T. gondii: the tachyzoites, the bradyzoites, and the oocysts. The tachyzoite is a rapidly multiplying stage and the main pathogenic factor. In North America and Europe, T. gondii is consisted of four major clonal lineages (namely Types I, II, III, and Type 12). In this study, we explored the proteomic profiles of different genotypes (Type I-RH strain, Type II-PRU strain, Type II-TgQHO strain, and ToxoDB 9-TgC7 strain) of T. gondii tachyzoites by using 2D DIGE combined with MALDI-TOF MS. Totally, 110 differentially abundant protein spots were selected. Of these, 98 spots corresponding to 56 proteins from T. gondii were successfully identified. These included surface antigen (SAG1), heat shock protein 70 (Hsp 70), disulfide isomerase, coronin, heat shock protein 60 (Hsp 60), pyruvate kinase, receptor for activated C kinase 1, and peroxiredoxin. Gene ontology enrichment analysis revealed that most of the differentially abundant proteins were involved in biological regulation, metabolic process, response to stress, binding, antioxidant activity, and transporter activity. According to the KEGG metabolic pathway maps of T. gondii, some identified proteins were involved in the glycolytic/gluconeogenesis pathway. The present study identified differentially abundant proteins among different genotypes of T. gondii and these findings have implications for the better understanding of the phenotypic differences among the examined T. gondii genotypes, which in turn may contribute to the better control of toxoplasmosis.

Serological report of pandemic (H1N1) 2009 infection among cats in northeastern China in 2012-02 and 2013-03.

BACKGROUND: Influenza A virus has a wide range of hosts. It has not only infected human, but also been reported interspecies transmission from humans to other animals, such as pigs, poultry, dogs and cats. However, prevalence of A (H1N1) pdm09 influenza virus infections in cats in northeastern China is unknown. Therefore, the prevalence of A (H1N1) pdm09 influenza virus infections was performed among cats in northeastern China in this study. FINDINGS: Of all samples in this study, the overall seroprevalence of pandemic (H1N1) 2009 infection in cats was 21% (240/1140). It also showed a higher prevalence rate of pandemic(H1N1) 2009 infection in pet cats (30.6%) than roaming cats (11%) based on NT. In addition, the results also showed a trend of difference in term of species of cats and it was statistically significant. CONCLUSIONS: This is the first survey on the seroprevalence of pandemic (H1N1) 2009 infection among cats in northeastern China. This study has observed a relatively high seroprevalence of pandemic (H1N1) 2009 among different cat populations in northeastern China, similar seroprevalence studies should be conducted elsewhere.