Phytochemical screening and antibacterial activities of Momordica charantia and Vernonia amygdalina extracts on some selected enteric isolates

Background:This research focuses on herbal medicine,an ancient healthcare practice,exploring the antibacterial attributes of fresh and dried leaf extracts from Momordica charantia(commonly known as Bitter melon)and Vernonia amygdalina(Bitter leaf).The study specifically investigates their effects on different bacterial strains associated with gastroenteritis.Methods:Four enteric bacterial isolates-Klebsiella pneumoniae,Salmonella typhi,Escherichia coli,and Proteus mirabilis-were obtained from the Medical Laboratory Unit at Babcock University Teaching Hospital in Ilishan-Remo,Ogun State.Phytochemical screening and antibacterial testing were conducted using standard biochemical techniques and the Punch-hole agar diffusion method,respectively.Results:Qualitative phytochemical screening of the plant extracts revealed the presence of flavonoids,glycosides,and saponin in both plants,excluding terpenoids.Alkaloids were identified only in Vernonia amygdalina.Despite these phytochemicals,neither plant displayed inhibitory effects on the tested bacterial isolates(Escherichia coli,Proteus mirabilis,Klebsiella pneumoniae,and Salmonella typhi)when tested individually or in combination.Intriguingly,combining the fresh and dried leaf extracts of Momordica charantia and Vernonia amygdalina with a standard drug resulted in smaller mean zone diameters of inhibition(Escherichia coli range:14 mm–16 mm,Proteus mirabilis range:31 mm–35 mm,Klebsiella pneumoniae range:13 mm–22 mm,and Salmonella typhi range:35 mm–38 mm)compared to the drug tested alone(16 mm–45 mm).Conclusion:Despite previous indications of antibacterial properties in various extracts of V.amygdalina and M.charantia leaves,our study presents contradictory results,prompting the need for further investigation despite the presence of significant phytochemicals.

Comparison of Interfacial and Foaming Properties of Soy and Whey Protein Isolates

A comparative study on the foaming properties and behavior at the air-water interface of soy and whey protein isolates were made, Foams were obtained by the method of gas bubbling. The initial rate of passage of liquid to the foam （vi） and the maximum volume of liquid incorporated to the foam （VLEmax） were determined. The destabilization process of the formed foams was analyzed by a biphasic second order equation. Measurements of equilibrium surface tension （water/air） and surface rheological properties were carried out in a dynamic drop tensiometer. The foaming capacity （vi and VLEmax） and the stability of foams prepared with the whey protein isolates （WPI） were better than those formulated with the soy protein isolates （SPI）. WPI foams were more stable showing the lower values of rate constants of gravity drainage and disproportion. There were significant differences （P 〈 0.05） in the dilatational modulus in the surface rheology measurements, which were higher at the interface with WPI, implying greater resistance of the film formed to collapse and disproportion. In conclusion, WPI formed better and more stable foams than the SPI.

Molecular basis for identification of species/isolates of gastrointestinal nematode parasites

Gastrointestinal（GI） parasitism is the most serious constraint throughout the world in small ruminants which causes significant production loss in animals.GI parasites are major contributor to reduce productivity in terms of meat,milk and wool in animals.Control of GI parasite is done primarily by anthelmintic treatment where choice and schedule of treatment is done after identification and quantitation of individual parasite.Identification of GI parasites is done through microscopic method by identifying specific morphological characteristics of egg and larva（L3）.Since most of parasite eggs are having similar morphological characteristics, identification up to species level through microscopy is not possible in most of cases.To address this issue,molecular techniques are the viable alternative for identification of species as well as molecular level differences within a species（isolates） of parasites.Different DNA based molecular techniques viz.PCR,AFLP,RAPD,RFLP,PCR-SSCP,real time PCR,DNA microarray etc.have been used for identification and to assess the genetic diversity among parasite population.For identification of species,the characteristic sequence of genomic DNA of different species should differ to allow the delineation of species,but at the same time,no/minor variation within the species should exist.In contrast,for purpose of identifying population variants（strains/isolates）, a considerable degree of variation in the sequence should exist within a species.Various target regions,including nuclear ribosomal DNA（rDNA）,mitochondrial DNA（mtDNA） or repetitive DNA elements（microsatellite loci）,which show considerable variation in the number of repeats within individuals have been employed to achieve the identification of parasites species or strain.

Isolates identification and characteristics of microorganisms in biotrickling filter and biofilter system treating H_2S and NH_3

A combination system of biotrickling filter （BTF） and biofilter （BF）, adopting surfactant-modified clinoptilolite and surfactant- modified wood chip as the media respectively, was applied to treat H2S and NH3 simultaneously. The identification and sole carbon sources utilization patterns of isolates in the combination system were studied by Biolog system. The isolates were identified as Bacillus sphaericus, Geobacillus themoglucosidasius （55℃） and Micrococcus luteus （ATCC 9341） in BTF, and Aspergillus sydowii （Bainier ＆ Sartory） Thom＆ Church in BE Among 95 substrate classes supplied by Biolog system, the carboxylic acids and methyl esters had the highest utilization extent for the four species, followed by the amino acids and peptides. The descending sequence of carbon sources utilization capability of isolates was A. sydowii （52.6%）, M. luteus （39.5%）, B. sphaericus （21.6%）, and G. thermoglucosidasius （17.7%）.

Geographic Distribution of Mating Types in Magnaporthe grisea and the Relationship Between Fertile Isolates in China

377 isolates of Magnaporthe grisea were collected from 17 provinces in China and their geographic distribution of mating types and their fertility was tested with four standard isolates, KA3 and TH12 (Mat1.1) and Guy11 and TH16 (Mat1.2) provided by CIRAD. 73 fertile isolates were tested with SCAR markers of 13 pairs of primers. Preliminary results showed that the geographic distribution of M.grisea existed among isolates collected from the same location as well as different locations and the genetic relationship between fertile isolates of the fungus in China. The existence of sexual reproduction of M .grisea was explored in the field as well.

Molecular Characterization and Correlation with β-lactam Resistance of Streptococcus pneumonia Isolates in Hangzhou,China

Penicillin-binding proteins（PBPs） are the target of β-lactam antibiotics（the major treatment for Streptococcus pneumoniae infections）,and mutations in PBPs are considered as a primary mechanism for the development of β-lactam resistance in S.pneumoniae.This study was conducted to investigate the mutations in the PBPs of clinical S.pneumoniae isolates in Hangzhou,China,in correlation with β-lactam resistance.Results showed that 19 F was the predominant serotype（7/27） and 14 of the S.pneumoniae isolates were resistant to both penicillin G and cephalosporin.Genotyping results suggested that β-lactam-resistant isolates primarily exhibited single-site mutations in both the STMK and SRNVP motifs of pbp1 a in combination with double-site mutations in the STMK motif of pbp2 x,which might be the primary mechanisms underlying the β-lactam resistance of the isolates in this study.

Helicobacter pylori vacA s1a and s1b alleles from clinical isolates from different regions of Chile show a distinct geographic distribution

AIM： To establish the most common vacA alleles in Helicobacter pylori （ H pylon） strains isolated from Chilean patients and its relationship with gastritis and gastroduodenal ulcers, METHODS： Two hundred and forty five Hpyloriclinical isolates were obtained from 79 biopsies from Chilean infected patients suffedng from gastrointestinal diseases. An average of 2-3 strains per patient was isolated and the vac4 genotype was analyzed by PCR and 3% agarose electrophoresis. Some genotypes were checked by DNA sequencing. RESULTS： The most prevalent vacA genotype in Chilean patients was slb ml （76%）, followed by sla ml （21%）. In oontrast, the s2 m2 genotype was scarcely represented （3%）. The slb ml genotype was found most frequently linked to gastropathies （P〈0.05） rather than ulcers. Ulcers were found more commonly in male and older patients. Curiously, patents IMng in dties located North and far South of Santiago, thecapital and largest Chilean city, carried almost exclusively strains with the slb ml genotype. In contrast, patients from Santiago and cities located South of Santiago carded strains with either one or both sla ml and slb ml genotypes. Regarding the s2 m2 genotype, comparison with GenBank sequences revealed that Chilean s2 sequence was identical to those of Australian, American, and Colombian strains but quite different from those of Alaska and India. CONCLUSION： Differences in geographic distribution of the s and m vacA alleles in Chile and a relationship of slb ml genotype with gastritis were found. Sequence data in part support a hispanic origin for the vacA genotype. Asymmetric distribution of genotypes slb ml and s2 m2 recedes H Pyloristrain distribution in Spain and Portugal.

Antimicrobial Susceptibility Patterns of the Bacterial Isolates in Post-Operative Wound Infections in a Tertiary Care Hospital, Kathmandu, Nepal

Unrestrained anti-microbial resistance (AMR) among bacterial pathogens has made the management and treatment of post-operative wound infections difficult. This study assessed the current AMR patterns of bacterial isolates in post-operative wound infections in a tertiary care hospital in Kathmandu,Nepal. Pus swabs collected from post-operative wound infections and submitted for culture and sensitivity were included in this study. Isolation and identification of the organism was done by standard microbiological methods. Antibiotic susceptibility test was performed by Kirby Bauer disc diffusion method and result was interpreted as per National Committee for Clinical Laboratory Standards (NCCLS) guide lines. Of the 120 pus swabs processed for culture, 96 showed bacterial growth. Staphylococcus aureus 36 (37.5%) was the predominant gram positive isolate and Escherichia coli 24 (25%) was the major gram negative isolate .The infection was most prevalent in the age group 20-40 years. All S. aureus isolates were sensitive to aminoglycosides and vancomycin. Out of 36 S. aureus, 15 (41.66%) isolates were methicillin resistant S. aureus (MRSA). Staphylococcus epidermidis showed high resistance (50%-100%) to all antibiotics but were sensitive to vancomycin. All gram negative isolates showed high resistance against cephalexin (75%-100%) and ceftriaxone (25%-100%). Overall multi-drug resistant isolates were 66.7%. A high level of AMR was observed in gram negative bacterial isolates. Rational use of antibiotics and a regular monitoring of AMR patterns in post-operative wound infections are essential and mandatory to avert further emergence and spread of anti-microbial resistance among bacterial pathogens.

Association of Neutralization Sensitivity of HIV-1 Primary Isolates With Biological Properties of Isolates From HIV-1 Infected Chinese Individuals

Objective Although HIV-1 infection is prevalent in many regions in China, it remains largely unknown on the biological characteristics of dominant circulating isolates. This study was designed to isolate the circulating viral strains from different prevalent regions and to characterize their biological properties and neutralization sensitivity. Methods Primary viruses were isolated from fresh PBMCs using the traditional co-culture method and their capacity of inducing syncytium was tested in MT-2 cells. Meanwhile, their coreceptor usage was determined with two cell lines: Magi and GHOST (3) stably expressing CD4 and the chemokine receptor CCR5 or CXCR4. Furthermore, the sensitivity of these viruses to neutralization by HIV-1-infected patients’ plasma which were highly active to neutralize SF33 strain, was quantified in GHOST cell-based neutralization assay. Results Six primary viral strains were isolated from 4 separated regions. Isolates LTG0213,LTG0214 and XVS032691 induced syncytia in MT-2 cells, and used CXCR4 as coreceptor. Isolates XJN0021, XJN0091, or SHXDC0041 did not induce syncytia, and used CCR5 as coreceptor. Overall neutralization sensitivity differed among four representative strains: HIV-1 XVS032691>LTG0214>XJN0091≈SHXDC0041. Conclusion The neutralization sensitivity of HIV isolates is linked with the phenotype of isolates, in which syncytium-inducing (SI) or CXCR4-tropic (X4) viruses are more easily neutralized than non-syncytium-inducing (NSI) or CCR5-tropic (R5) viruses. The genetic subtypes based on the phylogeny of env sequences are not classical neutralization serotypes.

Hydrophilic/hydrophobic characters of antimicrobial peptides derived from animals and their effects on multidrug resistant clinical isolates

Multidrug resistant（MDR） pathogen infections are serious threats to hospitalized patients because of the limited therapeutic options. A novel group of antibiotic candidates, antimicrobial peptides（AMPs）, have recently shown powerful activities against both Gram-negative and Gram-positive bacteria. Unfortunately, the viability of using these AMPs in clinical settings remains to be seen, since most still need to be evaluated prior to clinical trials and not all of AMPs are potent against MDR clinical isolates. To find a connection between the characteristics of several of these AMPs and their effects against MDR pathogens, we selected 14 AMPs of animal origin with typical structures and evaluated their in vitro activities against clinical strains of extensive drugresistant Acinetobacter baumannii, methicillinresistant Staphylococcus aureus, extended spectrum β-lactamase-producing Pseudomonas aeruginosa and extended spectrum β-lactamase-producing Escherichia coli. Our results showed that these peptides＇ hydrophilic/hydrophobic characteristics, rather than their secondary structures, may explain their antibacterial effects on these clinical isolates. Peptides that are amphipathic along the longitudinal direction seemed to be effective against Gramnegative pathogens, while peptides with hydrophilic terminals separated by a hydrophobic intermediate section appeared to be effective against both Gramnegative and Gram-positive pathogens. Among these, cathelicidin-BF was found to inhibit all of the Gram-negative pathogens tested at dosages of no more than 16 mg/L, killing a pandrug-resistant A. baumannii strain within 2 h at 4×MICs and 4 h at 2×MICs. Tachyplesin III was also found capable of inhibiting all Gram-negative and Gram-positive pathogens tested at no more than 16 mg/L, and similarly killed the same A. baumannii strain within 4 h at 4×MICs and 2×MICs. These results suggest that both cathelicidin-BF and tachyplesin III are likely viable targets for the development of AMPs for clinical uses.

Kinetics of Serum and Local Leukotriene B₄Response in Experimental Intravaginal Trichomoniasis by <i>T. vaginalis</i>Isolates from Symptomatic and Asymptomatic Women

Trichomoniasis is most common sexually transmitted disease caused by T. vaginalis. The clinical manifestation varies from severe manifestation to asymptomatic condition. However, the exact virulence markers led to varied symptomatology was not well clarified. The role of leukotriene B4 (LTB4) in the pathogenesis of many parasitic diseases has been reported. The present study reports the leukotriene B4 levels on different days post infection (3rd, 7th, 14th, 21st and 28th d.p.i.) in serum and vaginal washes (VWs) and vaginal tissues of mice infected intravaginally with T. vaginalis isolates from 10 symptomatic and 10 asymptomatic women. A significant increase in LTB4 was observed on the 3rd to 28th d.p.i. in serum and VWs of mice infected with T. vaginalis isolates from asymptomatic as compared to symptomatic women. The present study also reports the histopathological changes of the posterior vaginal fornix’s and upper portion of the vagina of mice infected intravaginally with T. vaginalis isolates from 10 symptomatic and 10 asymptomatic women. The results show that there are no significant differences between symptomatic and asymptomatic isolates regarding histopathological changes.

Bacterial Blood Isolates in Children: Conventional vs. Bactec Automated Blood Culture System in a Tertiary Health Centre in Gombe, North East Nigeria

Background/Aim: Blood culture is critical in the diagnosis and treatment of blood stream infections (BSIs) especially in children. BSIs are among the most common cause of morbidity/mortality and blood culture has remained the gold standard for diagnosis. We sought to compare Blood Culture Isolates (BCI) from conventional and Bactec automated blood culture system (ABCS) among paediatric patients at the Federal Teaching Hospital Gombe (FTHG) Nigeria. Methods: BCI in children (0 - 18 years) by conventional method from 2008-2012 and Bactec Automated culture system from 2015-2020 were retrieved from the clinical microbiology laboratory register. Information analyzed included, age, sex, month, and year and blood culture isolates. Results: There were 5276 (56.9% males, 43.1% females) and 1169 (54% males, 46% females) Blood Culture Isolates by CM and ABCS respectively. Overall positive culture isolates were 9.7% (515/5276) in CM and 45.9% (536/1169) in ABCS (p = 0.01). Positivity rate in newborn was 13.3% (282/2114) by CM and 40.9% (219/263) by ABCS p = 0.01;under-5 was 10.5% (448/4253) vs. 37% (359/873) (p = 0.01);Gram positive 32.6% (172) vs. 65% (759) (p = 0.01;Gram negative 55% (2910) vs. 34% (397) (p = 0.01). Staph aureus 22% (114/515) by CM vs. 61.9% (332/536)) by ABCS (p = 0.01);Klebsiella 24.9% (128/515) by CM vs. 7.5% (40/536) p = 0.01) in ABCS, E. coli 8.9% (46/515) vs. 2.1% (11/536) p = 0.01;Proteus vs. 1.1% (6/515) by ABCS, Pseudomonas 3.3% (17/515) vs. 5.6% (30/536) p = 0.05, Alkaligenes 1% (5/515) vs. 8.2% (44/536) p = 0.01 and Citrobacter 1% (5/515) vs. 8.4% (45/536) p = 0.01. Conclusion: Blood culture yield was five times higher with Bactec compared with Conventional method.

Molecular Characteristics and Drug Susceptibility of Mycobacterium tuberculosis Isolates from Patients Co-infected with Human Immunodeficiency Virus in Beijing,China

70 clinical Mycobacterium tuberculosis strains isolated from AIDS patients in two HIV/AIDS referral hospitals in Beijing were used in this study.M.tuberculosis and non-tuberculosis mycobacterium（NTM）were identified by using multi-locus PCR.M.tuberculosis was genotyped by using 15-locus MIRU-VNTR technique and spoligotyping afterwards.Meanwhile,the drug susceptibilities of the strains to the four first-line anti TB drugs（rifampin,isoniazid,streptomycin, and ethambutol） and the four second-line anti-TB drugs （capreomycin, kanamycin, ofloxacin, and ethionanide） were tested with proportional method. In this study, M. tuberculosis and NTM strains isolated from AIDS patients with TB-like symptoms were identified and genotyping analysis indicated that Beijing genotype was the predominant genotype. In addition, the prevalence of drug-resistant TB, especially the prevalence of XDR-TB, was higher than that in TB patients without HIV infection.

Genetic diversity of atoxigenic Aspergillus flavus isolates from peanut kernels in China

Aflatoxin contamination in peanuts is a major threat to public health, especially in tropical and subtropical regions of the world. Recently, the use of atoxigenic Aspergillus flavus strains as biological control agents prove to be effective in reducing aflatoxin contamination in crops. A total of 208 atoxigenic A. flavus isolates, collected from peanut kernels, were grouped into 7 deletion patterns by quadruplex PCR products of nor-1, ver-1, aflR and omtA genes. 49 SNPs, found in 1254 bp fragment of omtA gene, showed genetic variation of omtA among different A. flavus isolates. These isolates were assigned to either MAT1-1 type or MAT1-2 type with primers for each MAT locus. Thus, rich genetic diversity was found in the atoxigenic A. flavus isolates of peanut in China. The results indicated that quadruplex PCR would be an effective method for rapid screening of atoxigenic isolates with gene deletion in aflatoxin biosynthetic cluster.

A comparative study of bacterial isolates from the urine samples of AIDS and non-AIDS patients in Benue,Nigeria

Objective:To determine the common bacterial causes of urinary tract infection and their antibiotic susceptibility pattern in AIDS patients versus non-AIDS patients.Methods:One thousand consecutive AIDS patients with signs and symptoms of AIDS and non-AIDS patients (served as control) each on admission were recruited into the study between January 2005 to January 2008,in Federal Medical Center,Makurdi.Urine samples were collected with sterile universal bottles and analysed with appropriate laboratory methods and antibiotic susceptibility test was carried out by disk diffusion technique in accordance with National Committee for Clinical Laboratory Standards(NCCLS,now CLSI) criteria.The results were analysed using SPSS 11.0 statistical software.Results:Urine samples of AIDS patients with urinary infection had a more spectrum of micro-organisms including Candida organisms,Pseudomonas aeruginosa and Staphylococcus aureus.Ceftriaxone,Ceftazidime or Ciprofloxacin had a remarkably high anti-bacterial activity across the two study groups.A general resistance was recorded in ampicillin.tetracycline and co-trimoxazole.There was no significant difference in antibiotic susceptibility patterns between AIDS and non- AIDS patients(P】0.05).Conclusions:A reduction in unnecessary use of antibiotics as well as infection control should be encouraged in our health facilities.

Quick screening and easy detection method of NDM-gene in clinical isolates:A need of the time

The emerging trend of multidrug resistance is becoming a major threat to community acquired and nosocomial infections,worldwide[1].The carbapenems are used as last-source drugs because of increasing resistance against beta-lactam groups of antibiotics due to its excessive use to treat wide range of infections[2].The

Molecular characterization and phylogenetic analysis of Middle East 2009 H1N1 pdm isolates

Objective:To study hemagglutinin genetic evolution of some Middle East(ME) 2009 H1N1 pdm isolates and compared them with prototype vaccine strain[A/California/07/2009(H1N1)],which is used as a vaccine strain in the Northern Hemisphere 2010-2011.Methods:Nucleotide and/ or amino acid sequences of HA gene of fifty-four ME 2009 H1N1 pdm isolates were retrieved from GenBank Database by using Basic BLAST engine.Phylogenetic trees were established for both nucleotide and amino acid sequences using the muscle algorithm of the computer program CLC free workbench 5.6.1 JRE software.Amino acids alignment was also done to compare sequences HA1 domains of HA genes of ME 2009 H1N1 pdm isolates(n=39) with amino acid sequence of prototype vaccine strain A/California/07/2009(H1N1).Results:Phylogenetic analysis of amino acids and nucleotides of the HA gene of the ME 2009 H1N1 pdm isolates confirmed their evolutionary position in cluster with prototype vaccine strain(A/California/07/2009(H1N1)) which is used as vaccine strain in the Northern Hemisphere 2010-2011.Antigenically,the ME 2009 H1N1 pdm isolates were homogeneous and closely related to prototype vaccine.Only a few amino acid substitutions in the HA among the ME 2009 H1N1 pdm isolates were analyzed.Conclusions: The current influenza vaccine is expected to provide a good protection against ME 2009 H1N1 pdm because it contains strains with H1HA[A/California/07/2009(H1N1)]-like strain.

Amino Acid Composition of Cowpea (<i>Vigna ungiculata</i>L. Walp) Flour and Its Protein Isolates

The study of the nutritive value of Cowpea (Vigna ungiculata L.) legume seed is needed, as this legume is a food source in many developing countries. Whole Cowpea Flour (WCF), Dehulled Defatted Cowpea Flour (DDCF), and Cowpea Protein Isolates (CPI) prepared using Isoelectric method (CPII) and using Micellization method (CPIM) are studied. In proximate analysis, the protein content of WCF, DDCF, CPIA and CPIB was found to be 22.3, 26.7, 750 and 76.0 g/100 g, respectively. Net protein value (NPV) was 17.62 for DDCF. Chemical score was 0.66% for DDCF and 112%, 104% for CPII and CPIM, respectively. The first limiting amino acid was cystine for DDCF and threonine for CPII and CPIM. Methionine was found to be the most concentrated essential amino acid in both CPII and CPIM;values were 27.22 and 30.60 g/16 g N, respectively, while lysine was the most abundant essential amino acid in DDCF (4.28 g/16 g N). Essential amino acids of CPIi and CPIM were 22.99 and 15.78 g/16 g N respectively, higher than FAO/WHO reference.

Severe <i>Citrus tristeza virus</i>Isolates from Eastern Mexico Are Related to the T36 Genotype Group

Citrus tristeza virus (CTV) outbreaks have been reported in the main citrus growing region of Mexico in the past four years. Recently, in eastern Mexico (the major citrus-growing region in the country), severe CTV isolates have been detected. However, the molecular identity of observed isolates remains unestablished. This research was undertaken to elucidate the molecular characterization of CTV populations spreading in this region and to compare it with phylogeny of existing isolates. Genotyping of 32 collected isolates was performed using reverse-transcription polymerase chain reaction (RT-PCR) with sequence analysis of the coat protein (CP) gene, putatively associated with pathogenicity. This protein is a 25 kDa major capsid protein, which forms a long virion body coating 95% of the particle length. A comparative sequence analysis was performed using CTV sequences from different geographical origins already published and deposited in the GenBank databases. Phylogenetic analysis showed that the degree of sequence divergence among isolates correlated with their pathogenicity. Based on the sequencing results, the collected isolates were categorizedn as mild or severe phylogenetic clusters, each being genetically distinct. The severe group was associated with either a-like or with a T36-like genotype. The latter group matched with the quick decline and stem pitting drastic symptoms observed in the field. This study identified the presence of severe CTV isolates related to the T36-like genotype and to the cause of quick decline and stem pitting in sweet orange propagated on sour orange rootstock. Knowledge derived from these analyses could serve to design management strategies for this disease and to understand the current epidemic outbreak in scenarios where the most efficient vector is present.

Research on Propagation Characteristics of DifferentIsolates of Porcine Circovirus Type 2 in vivo

[Objective]The aim of this study is to explore the dynamic changes of Porcine circovirus type 2 (PCV2) and the propagation differences between different PCV2 strains.[Method]A rapid, sensitive and SYBR Green I-based real-time quantitative PCR assay was developed to detect PCV2 in mice. The Balb/c mice were inoculated with 200 μL of 1×10^6 TCID 50 /mL different strains of PCV2;the serum and tissues of mice were collected at different time. SYBR Green I fluorescent quantitative PCR was used to determine the viral titer in the serum and tissues of mice.[Result]The results indicated that the SYBR Green I PCR could speci fically detect PCV2 with high specificity. All strains were detected in the serum 14 d after infection, and 2007HA strain had the highest level of 1.21×10^8 copies/mL. The titers of all strains decreased 21 d after infection and then increased 28 d after infection. In addition, 2010NJ strain had the highest titer in serum 28 d after infection. The two PCV2b isolates, 2010NJ and 2009ZJ, had the highest titer in lungs and spleens. [Conclusion]All results showed that different PCV2 isolates have different proliferation ef ficiencies in Balb/c mice, even if they belong to the same subtype. In addition, the proliferation rate of 2009ZJ in visceral organs was significantly higher than that in serum. However, this phenomenon is not obvious for other strains. These results laid a foundation for the analysis of proliferation characteristics and pathogenicity of different PCV2 strains in vivo.