[Molecular epidemiological characteristics of HIV-1 strains isolated from newly diagnosed MSM subjects (2006-2010) in Beijing, China].

This study aims to analyze the molecular epidemiological characteristics of HIV-1 strains prevailing among men who have sex with men (MSM) in Beijing, China. The pol gene fragments from 250 newly diagnosed HIV-1-infected MSM individuals during 2006-2010 in Beijing were amplified by RT-nested PCR, sequenced, and phylogenetically analyzed. HIV-1 pol gene from 189 individuals were amplified and analyzed; 81 (42. 9%), 3 (1. 6%), 2 (1.0%), 88 (46. 6%), and 15 (7.9%) individuals were infected with HIV-1 subtypes B, B', C, CRF01_AE, and CRF07_BC, respectively. The subtypes B and CRF01_AE could both be grouped into two clusters, and CRFO7_BC strains shared high homology and were presumed to originate from a common ancestor. The HIV-1 circulating in MSM in Beijing had a lower genetic diversity than in heterosexuals. The HIV-1 epidemic (2006-2010) in MSM in Beijing was actually a rapid spread of HIV-1 CRF01 AE and B, or rather native strains of the two viruses.

[Molecular epidemiological characteristics of HIV-1 B'/C strains in Beijing].

OBJECTIVE: To analyze the molecular epidemiological characteristic of HIV-1 B'/C strains prevalent in Beijing. METHODS: Plasma samples were collected from 200 newly diagnosed HIV-1 B'/C individuals reported during 2006 to 2010 in Beijing. The gag gene fragments were amplified from RNA template extracted from plasma with reverse transcription (RT) and nested polymerase chain reaction (PCR). And the sequences were analyzed by phylogenetic methods and Entropy analysis. RESULTS: A total of 159 sequences were successfully amplified from the gag genes of which 147 was CRF07_BC and 12 CRF08_BC. There were 3 main sub-clusters in CRF07_BC phylogenetic tree and they were named as sub-cluster IDU-Max (89 sequences), sub-cluster IDU-Min (22 sequences) and sub-cluster MSM (34 sequences) based on transmission.No international reference strain was closely related with these three sub-clusters except for one strain identified in Taiwan. All CRF07_BC recombinant strains were remarkable for their low interpatient diversity in gag genes (3.7%, 3.3% and 2.0% for isolates from IDU-Max, IDU-Min and MSM respectively).When compared with sub-cluster IDU-Max, there were 32 and 41 significantly different sites of nucleotide polymorphism compositions in sub-clusters IDU-Min and MSM. CONCLUSION: This is the first report of describing the existence of three main epidemic sub-clusters in CRF07_BC strains prevalent in Beijing. And IDU-Max sub-cluster is the dominant strain. The CRF07_BC in Beijing are less diverse than other strains and may be derived from a common ancestor.

[Genetic characteristics of viral quasispecies of HIV-1 CRF07_BC among intravenous drug users].

To explore the genetic characteristics of viral quasispecies in HIV-1 CRF07_BC infections among intravenous drug users (IDU), the gp120 fragments of HIV-1 env gene were amplified from plasma samples collected from 6 CRF07_BC infected persons using single genome amplification and sequencing (SGA/ SGS) method, and 11 to 28 sequences were obtained from these samples, respectively, A neighbor-joining phylogenetic tree was reconstructed to describe the genetic characteristics of viral quasispecies. The Simplot, segments' phylogenetic trees and diversity plots based on average pairwise distance (APD) were used to identify the recombination events between quasispecies. The SGA sequences derived from single specimen formed a large monophyletic cluster in the neighbor-joining phylogenetic tree and showed the complex topologic structures of viral quasispecies. Of the 6 CRF07_BC infected patients, only one possessed the high genetic homogeneity, whereas the other five individuals showed high heterogeneity, with two to four subclusters inside the monophyletic cluster for each specimen. In addition, the recombinant events were identified among viral quasispecies from 3 cases. The results show SGA technique and phylogenetic analyses are useful tool to investigate the intrahost CRF07_BC gp120 complex quasispecies variation and high genetic diversity.

[Molecular-epidemiological characteristics of HIV-1 isolated from newly diagnosed female subjects in Beijing, 2006 - 2010].

OBJECTIVE: To analyze the molecular-epidemiological characteristics of HIV-1 strains prevailing among female people living with HIV in Beijing. METHODS: Gag gene fragments from the 100 newly diagnosed female HIV-1 infections during 2006 to 2010 in Beijing were amplified, sequenced, and phylogenetically analyzed. RESULTS: Eighty-two HIV-1 gag gene fragments were amplified and analyzed. 1 (1.22%), 1 (1.22%), 3 (3.66%), 23 (28.05%), 8 (9.76%), 2 (2.44%), 1 (1.22%), 18 (21.95%), 3 (3.66%), 1 (1.22%), 14 (17.07%), 4 (4.88%) and 3 (3.66%) individuals were infected with HIV-1 subtypes A1, A2, B, B', C, D, G, H, CRF01_AE, CRF02_AG, CRF07_BC, CRF08_BC and B'/C recombinants respectively. CONCLUSION: The subtypes circulating in female HIV infections in Beijing were more diverse than in male and the proportions of B' and rare subtypes were relatively high. Surveillance programs on HIV-1 genetic diversity should be strengthened.

Genetic diversity of HIV type 1 isolated from newly diagnosed subjects (2006-2007) in Beijing, China.

The purpose of this study was to investigate the genetic diversity of HIV-1 circulating in Beijing and its molecular epidemiological linkages with regard to risk factors of viral transmission. HIV-1 from plasma samples of 280 diagnosed individuals (2006-2007) was characterized. The gene fragments of gag, pol, and env from the infected plasma samples were amplified by reverse transcriptase polymerase chain reaction (RT-PCR), sequenced, and phylogenetically analyzed. From the 280 plasma samples analyzed, a total of 496 sequences were successfully amplified from the gag, pol, and env genes. Nine HIV-1 group M subtypes or CRF including A1, B, B', C, CRF01_AE, CRF02_AG, CRF06_cpx, CRF07_BC, and CRF08_BC, and six new B'/C recombinants were identified. CRF07_BC was found to be the most dominant subtype (32.5%) followed by CRF01_AE (25.0%), B (20.0%), and B' (15.7%). The data from this study indicate the existence of multiple HIV-1 subtypes or CRFs in Beijing and may be proven useful in the development of vaccine candidates in the future.

The prevalence of drug resistance mutations among treatment-naive HIV-infected individuals in Beijing, China.

To investigate the prevalence of HIV-1 genotypic mutations for drug resistance among patients in Beijing, blood samples from 145 newly confirmed (2006-2007), treatment-naive HIV-1-infected individuals were analyzed. Seven subtypes or CRF were subsequently determined and scored by the Stanford HIV Drug Resistance algorithm: CRF01_AE HIV-1 (27.6%), subtype B' (24.1%), CRF07_BC (21.4%), subtype B (20.7%), CRF08_BC (3.4%), subtype C (2.1%), and CRF06_cpx (0.7%). Eleven of the 145 subjects studied were found to harbor the strains resistant to either protease inhibitors (PIs) (3.4%), or nucleoside reverse transcriptase inhibitors (NRTIs) (2.1%), or nonnucleoside reverse transcriptase inhibitors (NNRTIs) (3.4%). Although the prevalence of drug resistance was relatively low among the treatment-naive HIV-1 patients in Beijing in comparison to those in industrialized countries, we will continue monitoring newly infected subjects for any potential alteration of the prevalence pattern to ensure the success of the ongoing scale-up of antiretroviral treatment.

[Genotypic resistance mutations to antiretroviral drugs in newly confirmed human immunodeficiency virus infectors in Beijing].

OBJECTIVE: To examine the prevalence of drug resistance mutations among the treatment-naive HIV (human immunodeficiency virus) infectors living in Beijing so as to provide the basal information for clinical antiviral treatment. METHODS: HIV pol genes from plasma samples of 150 treatment-naive HIV-infected patients were amplified, sequenced and phylogenetically analyzed. And the drug-resistance associated mutations in protease and reverse transcriptase regions were analyzed with Stanford University HIV Drug Resistance Database. RESULTS: A total of 111 pol gene sequences were obtained. The overall prevalence of drug resistance was 8.1% (9/111), corresponding to 3.6% (4/111) for protease inhibitors, 1.8% (2/111) for nucleoside reverse transcriptase inhibitors and 3.6% (4/111) for non-nucleoside reverse transcriptase inhibitors. No drug resistance mutation was identified in 17 intravenous drug users. CONCLUSION: The prevalence of drug resistance is relatively high in the newly confirmed HIV infectors in Beijing. Regular surveillance and monitoring of drug-resistant HIV should be implemented.

A new approach for sequencing virion genome of Chinese HIV-1 strains subtype B and BC from plasma.

BACKGROUND: Although it was widely accepted that full-length HIV genome sequences is important in studying virus genetic evolution and variation as well as developing vaccine candidate, to directly sequencing HIV-1 genome of virion RNA remains as a challenge worldwide. Up to date, no published genomic sequences from virion RNA are available for Chinese prevalent HIV-1 strains due to the absence of specialized protocol and appropriate lab equipments. In this study we developed a straightforward approach for amplifying and sequencing HIV virion RNA from plasma by modifying published protocols and further confirmed it is suitable to process Chinese samples. METHODS: The methods for viral RNA extraction and gene amplification was modified and optimized as could be widely used in most Chinese labs. Gene alignment of Chinese HIV-1 strains was employed for designing specialized primer sets for Thai-B and BC recombinant strains. Based on comprehensively consideration of high variable gene region and recombinant breakpoints in BC recombinant strains, a three-amplicon strategy (including 4.3-kb gag-pol, 2.9-kb pol-env and 2.7-kb env-nef) was developed. In addition, one amplicon (9 kb near full-length genome) was also used in 32 samples with varied viral loads. All amplicons were directly sequenced by DNA automated sequencer. RESULTS: Twenty-five percent (8/32) amplification efficiency was achieved by the one-amplicon strategy and 65.6% (21/32) by three-amplicon strategy. For one amplicon strategy, none of complete near full-length genome sequences was obtained by DNA sequencing. For three-amplicon strategy, 75% sequences were achieved in DNA sequencing. Amplification efficiency but not sequencing efficiency was closely associated with viral loads. CONCLUSION: Three-amplicon strategy covering all encoding regions of HIV-1 is suitable for Thai-B and BC recombinant strains and could be potentially employed in less-well equipped Chinese labs.

Sequence analysis of the gag-pol gene of human immunodeficiency virus type 1 of intersubtype (B'/C) recombinant strain in Beijing, China.

Little is known about the molecular and biological properties of HIV-1 intersubtype B'/C in Beijing. To fill the gap, we sequenced and analyzed the gag-pol genes from 39 HIV-1 B'/C recombinant infectors in Beijing, China during 2007. The results show that 36 CRF07_BC and 2 CRF08_BC isolates have a structural profile identical or nearly identical to CRF07_BC or CRF08_BC according to sequences in the gag-pol regions. The CRF07_BC circulating in injecting drug users (IDUs) and heterosexuals forms a diverse phylogenetic tree and most isolates from homosexuals cluster together. However, all the B'/C recombinant strains were remarkable for their low interpatient diversity in gag-pol genes (3.1, 3.0, and 2.2% for isolates from IDUs, heterosexuals, and homosexuals, respectively). We identified I7V, E91G, N242T, and K361R in the gag gene and R290I (HXB2 positions) in the pol gene as signature amino acid substitutions characteristic of HIV-1 CRF07_BC from the Beijing lineage. In addition, one new B'/C recombinant was detected. These results may contribute to an understanding of HIV-1 in Beijing.

[Genetic characteristics of HIV-1 CRF01_AE strains circulating in Beijing].

OBJECTIVE: To analyze the genetic characteristics of HIV-1 CRF01_AE strains prevailing in Beijing. METHODS: Plasma samples were collected from the newly diagnosed HIV-1 individuals being reported during 2006 to 2008 in Beijing. Gag gene fragments were amplified from RNA template which were extracted from plasma by RT and nested PCR methods. 105 CRF01_AE sequences were analyzed by phylogcnetic methods and characterized through calculating the genetic distance and Entropy analysis. RESULTS: There were four main sub-clusters in the phylogenetic tree. We named them as sub-clusters Homo-Max (67 sequences), Hetero (6 sequences), Mix (8 sequences) and Homo-Min (18 sequences) respectively, based on the mode of transmission. It was found that no international reference strain was closely related to the sub-cluster Homo-Max, Hetero or Homo-Min, including 91 samples. The strains in sub-cluster Mix consisting 8 cases that were closely related to the strains identified in Thailand and Vietnam. Genetic distance analysis on gag genes showed that the diversity of sub-clusters Homo-Max and Homo-Min was obviously less than that of the sub-cluster Hetero or Mix. When compared with sub-cluster Mix, there were 37, 29 and 11 significantly different nucleotides polymorphism compositions sites in sub-clusers Homo-Max Homo-Min and Hetero. CONCLUSION: This was the first report describing that four main epidemic sub-clusters were existed in CRF01_AE strains prevailing in Beijing. The virus with sub-cluster Homo-Max was the dominant strain in this region with shorter period of circulation and higher proportion seen in the HIV-infected persons. The virus in sub-cluster Mix was highly homologic with the CRF01_AE strains from Thailand and Vietnam.

Unusual patterns of neural tube defects in a high risk region of northern China.

OBJECTIVE: To study the prevalence of different types of neural tube defects (NTDs) in Luliang Prefecture, Shanxi province, where the prevalence of NTDs is unusually high and the correlation between NTDs prevalence and patterns. METHODS: A surveillance population-based birth defects was performed in Luliang Prefecture, Shanxi province. RESULTS: The results of our study showed that the prevalence of NTDs was 2-fold higher in Luliang Prefecture than in other areas of Shanxi province. Unusual patterns of NTDs were found, however, multiple NTDs were relatively common in Luliang Prefecture, accounting for over 13% of all NTDs cases in China. CONCLUSION: The prevalence of NTDs is associated with its patterns.

[Genotypic drug-resistance of HIV-1 CRF01_AE in Zhejiang province, 2004-2007].

OBJECTIVE: To study the genotypic drug-resistant mutation among treat-naïve or treated patients infected with HIV-1 CRF01_AE in Zhejiang province during 2004-2007. METHODS: HIV-1 pol amplicons (PR + RT) from 13 treated and 43 treat-naïve patients were obtained by reverse transcription-polymerase chain reaction (RT-PCR). The sequences were analyzed for genotypic antiretroviral resistance through online tools (http://hivdb.stanford.edu). RESULTS: The median count of CD4+ T lymphocytes in 43 treat-naïve patients was 229 cells /mm3 and the median log10 viral load was 3.41. Some drug-resistant mutations were seen in these samples including amino acid 10, 46, 71, in the genes ofprotease (PR) and 103, 118, in the genes of reverse transcriptase (RT) whereas twenty-nine resistance mutations in the genes of PR and RT were obtained in the 13 treated patients (8/13, 61.5%). The high prevalence of drug-resistant mutations was observed in patients who had been receiving HAART (hight active antiretroviral therapy). Among them, cross drug resistance was dominant. Correspondingly, the median counts of CD4+ T lymphocytes and the log10 viral load were 186 cells/mm3 and 3.91. CONCLUSION: There was a low prevalence of genotypic drug-resistant mutations in treat-naïve patients, but higher drug-resistant mutation in treated patients. More attention should be paid to the transmission of drug-resistant HIV strains and the antiretroviral therapy recipe should be adjusted correspondingly for the development of ART drugs, intervention as well as clinical therapy programs.

[Primers of gag gene for HIV-1 subtyping in China and application thereof in practice].

OBJECTIVE: To design the appropriate primers of gag gene for HIV-1 subtyping in molecular epidemiology survey based on the genetic characteristics derived from the main HIV-1 strains prevailing in China. METHODS: The gag genes of HIV-1 CRF07_BC, CRF08_BC, and subtype C, together with subtyping reference sequences, were obtained from HIV sequence database. Referring to the alignments and genetic characteristics of HIV-1 full gag sequences, new primers of gag gene for amplification and subtyping were designed. The target fragment was used to construct neighbor-joining phylogenetic tree and evaluate its reliability. The newly designed primers (GUX/GDX) were used to amplify the plasma samples to evaluate their efficiency. RESULTS: The phylogenetic tree of 306/c-gag fragments (positions 836-1507 of HIV-1 strain HXB2) showed that CRF07_BC and subtype C strains formed clusters with low bootstrap values (59% for CRF07_BC and 70% for subtype C), and the phylogenetic tree could not distinguish the sequences of CRF07_BC, CRF08_BC, and subtype C very well. Whereas the sequences of CRF07_BC, CRF08_BC, and subtype C from GUX/GDX (positions 781-1861) were clustered separately with higher bootstrap values (99%, 99%, and 77% respectively). In practice, a very good amplification and sequencing efficiency with over 90% positive results on average were obtained with GUX/GDX. Five clusters of subtype B, C, CRF01_AE, CRF07_BC, and CRF08_BC were formed with higher confidence (Bootstrap values all above 80%). The reliable phylogenetic tree could be constructed based on the fragments sequenced only with antisense primer (GDX). CONCLUSION: Fragments obtained with GUX/GDX primers of gag gene can be used to reconstruct phylogenetic tree with high reliability to distinguish the HIV-1 strains circulating in China, especially for the major BC recombinant and subtype C strains, which provides a useful tool in HIV molecular epidemiologic research.

[Recombinant expression of human influenza A virus nucleocapsid protein and its antigenicity analyses].

OBJECTIVE: To prepare anti-recombinant protein antibody from immunized mice with recombinant nucleocapsid protein (NP) of human influenza A3 (IFV-A3) virus expressed in prokaryotic cell, and to explore the feasibility of utilizing anti-recombinant protein antibody to detect influenza A virus. METHODS: NP genes of human influenza A virus were analyzed with computer softwares of ClustalX, Antheprot, et al. to determine the antigenicity in conserved regions. Three different partial NP genes were harvested and cloned into pET-28(c) plasmid, the recombinant plasmids were induced to express partial NP segments in BL21 cells. The recombinant proteins were purified with Ni-agarose by affinity chromatography and immunized BALB/c mice. The polyclonal antisera harvested from mice were analyzed with Western Blot and immunohistochemistry assays to detect the reactions with IFV-A. RESULTS: Three recombinant plasmids were expressed with high yield in BL21 cells, about 15-20 mg/L. Western Blot results indicated that the three prepared antisera (1:2000) positively reacted with NP from IFV-A3-infected cells. And immunohistochemistry assays suggested that anti-NP1, anti-NP2, anti-NP3 antisera positively reacted with IFV-A3 or IFV-A1-infected MDCK cells, with titers of 1:640 to 1:1280. CONCLUSION: The recombinant NP of IFV-A3 would induce polyclonal antibodies with high titers in mice. The polyclonal antibodies would cross-react with IFV-A3 and IFV-A1. It is feasible to predict the antigenicity with systematical bioinformatics analyses and then induce anti-IFV antibodies with high dilutions, and it is possible to be utilized in the early detection and subtyping analyses of IFV-infections.

[Molecular characteristics of HIV-1 CRF01 _ AE strains in Zhejiang province].

OBJECTIVE: Using molecular epidemiology method to characterize human immunodeficiency virus type 1 (HIV-1) subtype CRF01 _ AE strains being prevailed in Zhejiang province. METHODS: Gag fragments of the HIV-1 strains were amplified by nested-polymerase chain reaction (nPCR) from the DNA extracted from whole blood of HIV-1 infected individuals in Zhejiang province. PCR products were sequenced and analyzed by phylogenetic method. RESULTS: 81 HIV-1 subtype CRF01 _ AE sequences were identified from the 192 samples that sequenced successfully. As one of the dominant subtypes in Zhejiang, CRF01 _ AE was transmitted mainly by heterosexual or homosexual contact in local residents. In migrants living in Zhejiang, CRF01 _ AE were transmitted mainly by heterosexual contact or injecting drug use. There were three main clusters in the phylogenetic tree which bootstrap value was larger than 60. We named the clusters with group MIX (47 sequences), group SEX (7 sequences) and group MSM (12 sequences) based on the transmission. Pairwise DNA distances in the gag region within the three groups and between CM240 were different (P = 0.000). Data through the analyses of deduced amino acid sequences from the three groups showed that several signature amino acid sites were distinct from the same positions of the subtype reference strains. CONCLUSION: The CRF01 _ AE strain prevailing in Zhejiang province was from several sources, transmitted by more than three different transmission routes, and becoming the main subtypes circulating in homosexual population in this study. More attention needs to be paid to the epidemic characteristic of CRF01 _ AE.

Correlation between birth defects and dietary nutrition status in a high incidence area of China.

OBJECTIVE: To investigate the association between birth defects and dietary nutrient intake in a high risk area of China. METHODS: A dietary survey was performed and serum folic acid was measured in women whose pregnancy was affected by neural tube defects (NTDs) or unaffected by any birth defects (BDs) in Zhongyang and Jiaokou Counties in Shanxi Province of China. RESULTS: The local average consumption of foods including dark green vegetables, fruits, fat and meat, and nutrient intake (e.g., energy, protein, retinol, riboflavin, vitamin E, and selenium) were lower than the national average level. In women of childbearing age, these regions, the intake of nutrients was much lower than the recommended nutrient intake (9%-77%). The case-control dietary nutrition study of women whose pregnancy was affected by BDs (including NTDs and congenital heart defects) demonstrated that, in early pregnancy, adequate nutrition (i.e., eating meat, fresh vegetables, fruit more than once a week) was a protective factor, while eating germinated potatoes was a risk factor. The geometrical mean (p5-p95) of serum folic acid in women with NTD birth defects was 9.6 nmol/L (3.6, 23.03), which was significantly lower than that in normal women (14.03 nmol/L). CONCLUSION: Women of childbearing age in the two counties of Shanxi Province, China, have a marked insufficient intake of some nutrients, especially folic acid, zinc, vitamins A and B12. This nutrient deficiency may be an important risk factor for the high prevalence of birth defects in these regions. Therefore, adequate dietary nutrition in early pregnancy can prevent BDs.

Selective screening for inborn errors of metabolism and secondary methylmalonic aciduria in pregnancy at high risk district of neural tube defects: a human metabolome study by GC-MS in China.

OBJECTIVE: Urease pretreatment-gas chromatography-mass spectrometry (UP-GC-MS) has become a valuable tool in the field of metabolome research, including analysis of inborn errors of metabolism (IEMs) and acquired metabolic disturbances secondary to nutrition or drugs. This research aims to screen IEMs in Chinese patients and to explore the cause of neural tube defects (NTDs), a congenital malformation very common in North China. DESIGN AND METHODS: Urine samples from 618 patients at high risk of IEMs in China were collected, and UP-GC-MS was performed in the selective screening. Urinary methylmalonate (MMA) levels in pregnancy with and without NTDs fetus, respectively, at Luliang district, a countryside region with NTDs incidence 227/10,000, Shanxi Province, North China, were analyzed by GC-MS-selective ion monitoring, and compared with that from control region. RESULTS: Among the 618 patients, 22 kinds and 59 cases of IEM were found. Methylmalonic aciduria (MMAuria) is on top of the list, followed by neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD), phenylketonuria (PKU), multiple carboxylase deficiency (MCD), etc. Satisfactory therapeutic effects have been achieved in patients such as NICCD, MCD, and galactosemia. At Luliang district, urinary MMA levels in pregnancy, no matter NTDs-affected or unaffected, are both significantly (P<0.01) higher than that in normal control, while serum B(12) levels in NTDs-affected pregnancy are significantly lower than that both in NTDs-unaffected group (P<0.01) and in normal control (P<0.01). Furthermore, B(12) <52.5 pmol/L is associated with a 7.78-fold increased NTDs risk (P<0.01) at Luliang district. CONCLUSIONS: Selective screening for IEMs by UP-GC-MS provides valuable evidences for the diagnosis of IEMs. MMAuria secondary to B(12) deficiency is quite common at Luliang district, suggesting B(12) deficiency is involved in the development of NTDs in the specific population. This metabolome research by UP-GC-MS provides valuable epidemiological information that helps to understand the prevalence and the possible intervention strategy of NTDs and IEMs, especially in Chinese population.

Intrauterine infections and birth defects.

Intrauterine infection is an important cause of some birth defects worldwide. The most common pathogens include rubella virus, cytomegaloviurs, ureaplasma urealyticum, toxoplasma, etc. General information about these pathogens in epidemiology, consequence of birth defects, and the possible mechanisms in the progress of birth defects, and the interventions to prevent or treat these pathogens' infections are described. The infections caused by rubella virus, cytomegaloviurs, ureaplasma urealyticum, toxoplasma, etc. are common, yet they are proved to be fatal during the pregnant period, especially during the first trimester. These infections may cause sterility, abortion, stillbirth, low birth weight, and affect multiple organs that may induce loss of hearing and vision, even fetal deformity and the long-term effects. These pathogens' infections may influence the microenvironment of placenta, including levels of enzymes and cytokines, and affect chondriosome that may induce the progress of birth defect. Early diagnosis of infections during pregnancy should be strengthened. There are still many things to be settled, such as the molecular mechanisms of birth defects, the effective vaccines to certain pathogens. Birth defect researches in terms of etiology and the development of applicable and sensitive pathogen detection technology and methods are imperative.