S2 Isolate Research Articles

Molecular characteristics and antimicrobial resistance profiles of Staphylococcus aureus isolates from burns.

Burns are a problem that affects millions of individuals around the world. This research aimed to analyze the genetic characteristics and antibiotic resistance of Staphylococcus aureus strains isolated from patients with burns. Identifying the genetic variations of three local strains of Staphylococcus aureus isolated from burns. Swab samples were collected from eighty sources (burns). Using sterile swabs containing media collected from patients treated at Baqubah Teaching Hospital between July 2022 and the end of September 2022, these samples were then cultured on blood agar and brain heart infusion agar. A total of twenty-four hours were spent incubating the cultured samples in an aerobic environment at 37°C. During this time, isolated growing colonies showed characteristic growth, color, and hemolysis, while suspicious colonies were cultured for further identification. Our results indicated the presence of several polymorphisms that were distributed in the investigated samples. However, almost all observed variations were concentrated only in the S2 isolates. The construction of phylogenetic trees confirmed this notion by positioning these S2-based amplicons to distinct categories within Staph. aureus organisms. Furthermore, the phylogenetic tree offered additional tools for the guaranteed identity of the samples that were analyzed. Consequently, the utilization of the PCR-sequencing approach in three DNA samples belonging to these local bacterial isolates has resulted in the confirmation of the identity of this strain. However, particular emphasis should be placed on S2 isolate as it has special variants that differ from its mates, in terms of its metabolic as well as phylogenetic consequences. Therefore, S2 isolates may represent a new strain that requires a whole genome sequencing strategy to validate its identity within Staph. aureus organisms. S.aureus resistance was 100% (Augmentin and Tetracycline), and 90% (Azithromycin and Trimethoprim), while Cefotaxime and Chloramphenicol recorded (75%, and 85%) respectively.

ZnO, TiO2 and Ag nanoparticles impact against some species of pathogenic bacteria and yeast.

The economic approaches for manufacturing the nanoparticles with physical and chemical effects and limited resistance to antibiotics have been progressed recently due to the rise of microbial resistance to antibiotics. This research aimed to study the antimicrobial efficacy of silver nanoparticles Ag, ZnO, and Tio2 nanoparticles against Salmonella typhimurium and Brucella abortus and Candida albicans. Two isolates of Salmonella and two isolates of Brucella abortus were isolated from food spastically meat and blood specimens, respectively. Candida albicans were isolated from the patient's mouth with oral candidiasis (oral thrush) and confirmed diagnosis by API 20C test. The antimicrobial susceptibility of Salmonella typhimurium and B. abortus isolates were performed against nine different antibiotics. Silver nanoparticles consisting of AgNPs size (90) nm, ZnO NPs size (20, 50) nm as well as TiO2 NPs size (10, 50) nm, were used. UV-Visible spectrophotometer was used to characterize silver nanoparticles. The highest resistance of Candida albicans was seen for fluconazole, Clotrimazole and Itraconazole. The results of the Minimum Inhibitory Concentration (MIC) of nanoparticles against Salmonella typhimurium showed the average MIC of Tio2-10nm and Tio2-50nm were 5000 and 2500 μg\ml for S1 and S2 isolates, respectively. The isolated Brucella abortus (B1 and B2) showed sensitivity to NPs with different MIC. The average MIC for Ag-90nm was 5000 and 2500 µg/ml for B1 and B2 isolates, respectively. The findings suggest NP solution has fungicidal and bactericidal impacts on the tested microorganisms so they can be suitable for multiple applications of the biomedical field such as developing new antimicrobial agents.

Antibacterial Screening of Actinomycetes isolated along the coast Bay of Bengal, Visakhapatnam

Till now numerous anti-microbials are accessible, yet some pathogenic creatures are demonstrating protection from existing anti-infection agents. So it is required to scan new anti-infection agents for opposing pathogenic life forms. Actinomycetes are excellent asset for delivering optional metabolites that is anti-microbials; they are Streptomycin, Erythromycin, and Tetracycline. Actinomycetes are accessible in both marine and earthbound environment. From earthly biological system disengagement of new strain Actinomycetes is exceptionally troublesome contrasted and marine environment. Marine environment is a best asset for some strains of actinomycetes, since it is unexplored biological system having a great many various kinds of organisms. Upto 1% of marine actinomycetes were separated, yet at the same time we need to investigate more for finding new organisms. The majority of the disengaged marine microorganisms are from Streptomyces class (70%), marine growths (20%), Bacillus spp. (7%) and other microbes (1%-2%). 40 isolates are obtained from sample, among them 8 isolates are selected from primary screening for antibacterial activity. Out of 8, 6 isolates showed antimicrobial activity against 4 test organisms. 2 isolates showed activity in secondary screening. S2 isolate showed broad antibacterial activity.

Repurposing INCI-registered compounds as skin prebiotics for probiotic Staphylococcus epidermidis against UV-B

Repurposing existing compounds for new indications may facilitate the discovery of skin prebiotics which have not been well defined. Four compounds that have been registered by the International Nomenclature of Cosmetic Ingredients (INCI) were included to study their abilities to induce the fermentation of Staphylococcusepidermidis (S. epidermidis), a bacterial species abundant in the human skin. Liquid coco-caprylate/caprate (LCC), originally used as an emollient, effectively initiated the fermentation of S. epidermidis ATCC 12228, produced short-chain fatty acids (SCFAs), and provoked robust electricity. Application of LCC plus electrogenic S. epidermidis ATCC 12228 on mouse skin significantly reduced ultraviolet B (UV-B)-induced injuries which were evaluated by the formation of 4-hydroxynonenal (4-HNE), cyclobutane pyrimidine dimers (CPD), and skin lesions. A S. epidermidis S2 isolate with low expressions of genes encoding pyruvate dehydrogenase (pdh), and phosphate acetyltransferase (pta) was found to be poorly electrogenic. The protective action of electrogenic S. epidermidis against UV-B-induced skin injuries was considerably suppressed when mouse skin was applied with LCC in combination with a poorly electrogenic S. epidermidis S2 isolate. Exploring new indication of LCC for promoting S. epidermidis against UV-B provided an example of repurposing INCI-registered compounds as skin prebiotics.

STUDY THE ANTIBACTERIAL ACTIVITY OF AQUEOUS EXTRACTION OF ONION (Allium cepaL) AGAINST Staphylococcus aureus ISOLATED FROM OTITIS MEDIA.

This study was aimed to determine the antibacterial activity of onion (Allium cepaL.) aqueous extract against S. aureus bacteria isolated from patients with otitis media. Twenty swabs samples were taken from patients with otitis infection; these samples were cultured on different agar media .Results revealed that half of these isolates were related to S. aureus and the five of these isolates were subject to sensitivity test against several antibiotic groups. Most of isolates 100% were resistance to amoxicillin, chloramphenicol, cefoxitin and pencillin, and 60 % of were showed resistance to cefotaxtime and tetracycline, where as 20 % were resistance to Ciprofloxacin. Depending on the results of antibiotic sensitivity, the two isolates(S2,S5) were chosen for determining the minimum inhibitory concentration (MIC) test, S2 isolate showed high-level of resistance at (16 and 128 µg/ml) to chloraemphenicol, amoxicillin, ampicillin and Cefotaxime respectively, while S5 at concentration (32, 64 and 128 µg\ml) were resistance to amoxicillin, ampicillin, chloraemphenicol and cefotaxtime. The MIC of onion extract against S. aureus was determined at two incubation periods The results were indicated that after 24 hrs, MIC of extract at 64 µg/ml was affected in inhibit the growth of S2 isolate, While 32 µg/ml was inhibited the growth of S5 isolate.However, after 72 hrs, It was found that the MIC at 32, 64 and 128 µg/ml were more effective in inhibited the growth of S2 and S5 isolates.

Identification of Endophytic Fungi from Fruits and Seeds of Jambolana (Syzygium cumini L.) Skeels

The endophytes are microorganisms that colonize plant tissue without causing infections. One of endophytic microorganisms, fungi, comprises a reliable source of genetic diversity and has been applied in pharmacology. In this study, the endophytic fungi was isolated from fruit and seed of Syzygium cumini and identified based on ITS-rDNA. Five fungal isolates were obtained from fruit and seed of Jambolana, two isolates from fruit and three isolates from seed. Based on ITS-rDNA analysis showed that that endophytic fungus isolates from jambolana (S. cumini L.) Skeels was identified as Neofusicoccum parvum (F1 isolates), Pestalotiopsis vismiae (F2 isolates), Phomopsis sp. (S1 and S3 isolates), Colletotrichum fructicola (S2 isolates). All the isolates are belonged to Ascomycota.

Bioaccumulation of cadmium by Enterobacter sp. and enhancement of rice seedling growth under cadmium stress

Bacteria-mediated plant growth promotion and bioremediation of heavy metal containing soil is a widely accepted eco-friendly method. The present study is aimed to screen out cadmium resistant bacterial strain from metal contaminated rice rhizosphere and evaluate its effects on the growth of rice seedlings under cadmium stress. Among four different isolates (designated as S1, S2, S3 and S5), the S2 isolate was screened on the basis of different PGP traits and multi heavy metal resistance (minimum inhibitory concentration for cadmium, lead and arsenic were 3500, 2500 and 1050 µg/ml respectively). The selected S2 strain has ability to produce ACC deaminase (236.11 ng α-keto-butyrate/mg protein/h), IAA (726 µg/ml), solubilize phosphate (73.56 ppm) and fix nitrogen (4.4 µg of nitrogen fixed/h/mg protein). The selected strain was identified as Enterobacter sp. on the basis of phenotypic characterization, MALDI-TOF MS analysis of ribosomal proteins, FAME analysis and 16 S rDNA sequence homology. The high cadmium removal efficiency (> 95%) of this strain from the growth medium was measured by Atomic Absorption Spectrophotometer and it was due to intracellular cadmium accumulation evidenced by SEM-EDX-TEM-EDX study. SEM analysis also revealed no distortion of surface morphology of this strain even grown in the presence of high cadmium concentration (3000 µg/ml). Inoculation of this strain with rice seedlings significantly enhanced various morphological, biochemical characters of seedling growth compared with un-inoculated seedlings under Cd stress. The strain also exhibited alleviation of cadmium-induced oxidative stress, reduction of stress ethylene and decreased the accumulation of cadmium in seedlings as well that conferred cadmium tolerance to the plant. Thus the S2 strain could be considered as a potent heavy metal resistant PGPR applicable in heavy metal contaminated agricultural soil for bioremediation and plant growth promotion as well. Main findingA cadmium resistant plant growth promoting Enterobacter sp. was isolated that accumulated cadmium evidenced by SEM-TEM-EDX study. It reduced Cd uptake and enhanced growth in rice seedlings.

Identification and characterisation of two novel azo dye degrading microorganisms from contaminated ground water and soil of a textile mill

Bacterial isolates were tested for biodegradability potential of azodyes. S1 and S2 isolate effectively decolorised all azodyes tested within 72 hours. These isolates were later characterised as Achromobacter and Bacillus sp. The resistance traits on plasmid were evidenced from curing experiments. Sodiumdodecyl sulphate (SDS) and rifampicin (9 mg/ml) was found to be most effective curing agent. Achromobacter sp. was positive for tryptophanase, indole and citrate permease with ability to ferment glucose and produced gas. While, S2 showed the presence of tryptophanase, but found negative for the urease. Both the isolates were able to sustain salt concentration between 4%-10% suggesting moderately halotolerant. Bacillus sp. exhibited tolerance to heavy metal, zinc and arsenic up to 8 M; copper, cobalt and nickel to an extent of 500 mM. Efficient decolorising activity, heavy metal and salt tolerance capability indicates that isolated strains can be utilised effectively for the treatment of effluents in the dye industries.

Experimental Hyalohyphomycosis by Purpureocillium lilacinum: Outcome of the Infection in C57BL/6 Murine Models.

Purpureocillium lilacinum is a filamentous, hyaline fungus considered an emerging pathogen in humans. The aim of our study was to evaluate the outcome of hyalohyphomycosis in C57BL/6 murine models inoculated with two clinical P. lilacinum isolates (S1 and S2). Each isolate was inoculated in mice randomly distributed in immunocompetent (CPT) and immunosuppressed (SPS) groups. Mice were evaluated at day 7, 21, and 45 after inoculation for histopathological analysis, recovery of fungal cells, and immunological studies. Histological analysis showed scarce conidia-like structures in lung tissue from CPT mice and a lot of fungal cells in SPS mice inoculated with S2 compared to mice inoculated with S1. The maximum recovery of fungal cells was seen in CPT mice inoculated with both isolates at day 7, but with mean significantly higher in those inoculated with S2 isolate. Phenotypical characterization of T cells showed TCD8+ lymphocytes predominance over TCD4+ in immunosuppressed mice infected and control groups. We also observed higher percentages of the central and effector memory/effector phenotype in CPT mice infected with S2 strain, especially in TCD8+ in the initial period of infection. Regulatory T cells showed higher percentages in immunosuppressed, predominantly after the acute phase. Our results showed that the P. lilacinum is a fungus capable to cause damages in competent and immunosuppressed experimental hosts. Furthermore, S2 isolate seems to cause more damage to the experimental host and it was possible to identify different cellular subsets involved in the mice immune response.

Hyper-Productivity, Characterization, and Exploitation of a Cellulase Complex from a Novel Isolate of Aspergillus tubingenesis S2 using Lignocellulose-based Material

The hyper-production potential of a cellulase complex from a local strain of Aspergillus tubingensis S2, indigenously isolated from rotten tomato, was investigated. A total of nine fungal species of Aspergillus and Trichoderma were isolated and confirmed through triple-phase screening via 18S ribosomal DNA sequencing and construction of a phylogenetic tree. Congo red testing and the zone of clearance method were used to confirm the cellulase production from A. tubingenesis S2 isolate. A. tubingenesis S2 revealed maximum cellulase production (78 µg/mL/min) and was selected for further study. The optimum fermentative conditions, including the incubation period, pH, and temperature values, were determined to be 96 h, pH 4.8, and 40 °C, respectively, for obtaining the cellulase activity of 86.4±2.1 µg/mL/min. The cellulase was 5.14-fold purified by ammonium sulfate fractionation and gel permeation chromatography. Characterization revealed that maximum activity (130.5 µg/mL/min and 133.5 µg/mL/min) was achieved at 4.5 pH and 40 °C, respectively. A monomeric protein with an apparent molecular weight of 76 kDa was evident after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Cellulase revealed maximal activity with 40-mesh size corn stover as compared with 20-mesh size corn stover and 80-mesh size corn stover after 36 h of incubation at 40 °C.

Giardia duodenalis Surface Cysteine Proteases Induce Cleavage of the Intestinal Epithelial Cytoskeletal Protein Villin via Myosin Light Chain Kinase.

Giardia duodenalis infections are among the most common causes of waterborne diarrhoeal disease worldwide. At the height of infection, G. duodenalis trophozoites induce multiple pathophysiological processes within intestinal epithelial cells that contribute to the development of diarrhoeal disease. To date, our understanding of pathophysiological processes in giardiasis remains incompletely understood. The present study reveals a previously unappreciated role for G. duodenalis cathepsin cysteine proteases in intestinal epithelial pathophysiological processes that occur during giardiasis. Experiments first established that Giardia trophozoites indeed produce cathepsin B and L in strain-dependent fashion. Co-incubation of G. duodenalis with human enterocytes enhanced cathepsin production by Assemblage A (NF and S2 isolates) trophozoites, but not when epithelial cells were exposed to Assemblage B (GSM isolate) trophozoites. Direct contact between G. duodenalis parasites and human intestinal epithelial monolayers resulted in the degradation and redistribution of the intestinal epithelial cytoskeletal protein villin; these effects were abolished when parasite cathepsin cysteine proteases were inhibited. Interestingly, inhibition of parasite proteases did not prevent degradation of the intestinal tight junction-associated protein zonula occludens 1 (ZO-1), suggesting that G. duodenalis induces multiple pathophysiological processes within intestinal epithelial cells. Finally, this study demonstrates that G. duodenalis-mediated disruption of villin is, at least, in part dependent on activation of myosin light chain kinase (MLCK). Taken together, this study indicates a novel role for parasite cathepsin cysteine proteases in the pathophysiology of G. duodenalis infections.

Identification and immunogenicity of Mannheimia haemolytica S1 outer membrane lipoprotein PlpF

Immunity against Mannheimia haemolytica requires antibodies against leukotoxin (LKT) and bacterial cell surface antigens, most likely immunogenic outer membrane proteins (OMPs). Five immunogenic outer membrane lipoproteins identified and characterized in M. haemolytica were designated Pasteurella lipoproteins (Plp) A, -B, -C, -D and -E. Using immunoproteomics, we identified a heretofore-uncharacterized M. haemolytica immunogenic outer membrane lipoprotein that we designated PlpF, which was previously designated in the published sequence as a conserved hypothetical protein. We cloned and expressed rPlpF from two M. haemolytica serotype 1 strains (SAC159 and SAC160) and demonstrated a variable number of perfect (KKTEED) or imperfect (KKaEEa) repeats between residues 41 and 76 on the N-terminus. Antigenicity plots predicted the N-terminus repeat region to be highly antigenic. The plpF gene in multiple M. haemolytica S1, S2, and S6 isolates varied in the number of repeats from three to seven. C-terminal region was highly conserved. Immunization of mice with SAC159 or SAC160 demonstrated immunogenicity in a dose-response manner. Immunization of calves demonstrated an increase in antibodies to PlpF, and rPlpF antibodies stimulated complement-mediated killing of M. haemolytica. Because calves had pre-existing anti-M. haemolytica antibodies due to prior natural exposure, functionality of the anti-PlpF antibody responses were demonstrated by marked reduction of complement-mediated killing by blocking of anti-PlpF antibodies with rPlpF In conclusion, PlpF might have vaccination potential against M. haemolytica infection in cattle.

Sequence diversity of the immunogenic outer membrane lipoprotein PlpE from Mannheimia haemolytica serotypes 1, 2, and 6

Mannheimia haemolytica serotype 1 (S1), S6 and S2 are the most common bacterial isolates found in shipping fever pneumonia in beef cattle. Currently used vaccines against M. haemolytica do not provide complete protection against the disease. Research with M. haemolytica outer membrane proteins (OMPs) has shown that antibodies to one particular OMP from S1, PlpE, may be important in immunity. Recombinant PlpE (rPlpE) is highly immunogenic in cattle, and the acquired immunity markedly enhanced resistance to experimental challenge. We previously demonstrated that the immunodominant epitope (R2) is located between residues 26 and 76 on the N-terminus of PlpE from a reference S1 strain ( Ayalew et al., 2004). This region consists of eight hexapeptide repeats. The potential of this epitope as a vaccine or supplement to commercial vaccines is dependant on its state of conservation amongst isolates of the three serotypes. To determine this, we sequenced plpE genes from 32 isolates. The sequences from S1 and S6 were identical with one exception. Substantial variation was observed among sequences from S2 strains, particularly in the R2 region of the protein. These variations in S2 isolates range from 3 to 28 hexapeptide repeats. Calculated molecular weight of PlpE from S1 and S6 isolates was 37 kDa, where as PlpE from S2 strains ranged from 30 to 50 kDa. These similarities and differences were demonstrated by western blot. Competitive binding assay was used to determine that antibody against rPlpE from S1 binds native PlpE on surfaces of both S1 and S2 cells.

Bacillus megaterium N4에 의한 들깨 균핵병 (Sclerotinia sclerotiorum)의 생물학적 방제

부산시 강서구 강동동 지역의 들깨 하우스내에서 들깨의 잎에 갈색내지 흑갈색의 병반이 형성되고 습도가 높을 시에는 잎에 무름증상과 줄기에 잘록증상이 나타나며, 심하면 주전체가 고사하여 흰색의 균사로 뒤덮히고 균핵이 형성되는 병해가 발생하여 1998년 5월에 자연발생된 균핵병 발병율을 조사한 결과 약 8.1～28.3%로서 평균 13.9%였다. 이러한 증상을 띄는 병반으로부터 분리된 16균주를 균사절편 접종법으로 병원성 검정한 결과, 접종 1일 후부터 발병되기 시작하여 자연발생된 병징과 동일한 증상을 나타내었으며 16균주 모두 80.0% 이상의 발병율을 나타내었다. 그 중 병원성이 가장 강한 52균주를 공시선발하고, 형태적 및 배양적 특성 등을 조사하여 동정한 결과, 들깨 균핵 병균 Sclerotinia sclerotiorum으로 동정되었다. 생물학적 방제를 위해 길항세균인 Nl 등 6균주를 공시하고 병원균 52균주와 균사생육 억제효과 및 생육상내 포트검정을 통해 방제효과를 검정한 결과, N4 균주에 의한 균사생육 억제효과와 방제효과가 가장 우수하였으며, 발병예방 및 치료효과 검정시 길항균을 병원균처리 1～3일 전에 처리할 경우 80.0% 이상의 방제가를 보여 치료 효과보다는 발병예방효과가 효과적인 것으로 확인되었다. 길항균 N4 균주를 Bergey's manual과 API system을 이 용하여 동정한 결과, Bacillus megaterium으로 동정 되었으며, 이를 수화제형인 미생물농약 N4제제로 제조하여 유기합성 농약인 베노밀수화제와 발병예방 및 치료효과를 비교하였다. 그 결과, 병원균처리 3일 전에 처리할 경우 N4 수화형 제제의 방제가가 98.0%로 베노밀수화제에 의한 78.0%보다 방제가가 높았다. This study was investigated the occurrence of sclerotinia rot caused by Sclerotinia sclerotiorum at the major perilla cultivating area, Gangdong-dong, Gangseo-gu, Busan in 1998. The incidence of this disease ranged from 8.1 to 28.3% at Gangdong-dong area during the growing seasons. Symptoms of the disease initially appeared damping-off of infected stems and soft-rot on the leaves of perilla. Under the relatively high humidity, abundant white mycelia of the pathogen formed on the lesion developed into black sclerotia later and the infected leaves were finally fell down. Sixteen isolates, Sl-S16, isolated from diseased lesions showing typical symptoms, and pathogenicity was tested using mycerlial disks. Among them, S2 isolate showing the most strong pathogenicity was selected and identified as Sclerotinia sclerotiorum on the basis of morphological and cultural characteristics. For biological control, an antagonistic bacteria, N4 isolate which effectively inhibited not only mycelial growth of S2 isolate but also suppress sclerotinia rot on the pot assay, was selected and identified as Bacillus megaterium according to Bergey's manual and API system., Wettable powder type, N4 formulation using B. megaterium N4 isolate was developed and estimated its control effect on perilla crops in a plastic house. As a results, N4 formulation which applied before 3 days inoculation of pathogen was effectually controlled Sclerotinia rot as the control value of 98.0%, was more effective than chemical fungicide, benomyl showing the control value of 78.0%. This is the first report of wettable powder formulation as a biocontrol agent using B. megaterium N4 against Sclerotinia rot caused by S. sclerotiorum on perilla.

Distribution, Pathogenicity, and Interactions of Two Strains of Rice yellow mottle virus in Forested and Savanna Zones of West Africa.

In Côte d'Ivoire, the S2 strain of Rice yellow mottle virus (RYMV) predominated in the forested zones, including the "rice belt" to the west, in each of the cropping systems where rice was grown. The S1 strain occurred more frequently in the northern Guinean savanna, and only S1 isolates were found further north in the Sahelo-Soudanian zones. In mixed infection, S2 dominated over S1 both in viral capsid and RNA contents under temperature regimes encompassing those observed in savanna and forested zones of Côte d'Ivoire. There was no evidence of interactions in virus accumulation between the West African strains S1 or S2 with the more distantly related East African strain S4. Field trials emphasized the impact of RYMV, which induced yield losses of 40 to 60% in several widely grown cultivars of Oryza sativa indica and O. sativa japonica. We report the high resistance of the O. indica cv. Gigante under field conditions which was apparent with all the S1 and S2 isolates tested. Responses to RYMV infection of several cultivars were isolate dependent. With most differential cultivars, responses were not strain specific, with the exception of the O. japonica cv. Idsa6, in which the S2 isolates always induced higher yield losses than the S1 isolates.

Evidence of the Presence of Two Serotypes of Rice Yellow Mottle Sobemovirus in Côte d'Ivoire

Serological variability of isolates of rice yellow mottle virus (RYMV) collected in Cote d'Ivoire was assessed by immunological tests with polyclonal and monoclonal antibodies (MAbs). Two serotypes (named S1 and S2) were distinguished. The S1 isolates had common epitopes which were absent in S2 isolates, whereas they lacked epitopes shared by S2 isolates. There was no evidence of S1 and S2 mixtures, although S1 and S2 isolates were sometimes found in nearby sites. Serotype S2 was more prevalent in Cote d'Ivoire than S1, and was in a large majority in the centre and the south of the country. By contrast, S1 occurred more widely in the north. S1 isolates were also found in neighbouring countries at the north of Cote d'Ivoire. In tests with monoclonal antibodies, three additional serotypes were found, one in West-Africa and two in East-Africa. Using the primers developed against an S2 isolate from Cote d'Ivoire, all S2 but not the S1 isolates were transcribed and amplified by RT-PCR, and another set of primers was developed to amplify S1 isolates. S1 and S2 have different biological properties, and competition between isolates of the two strains was apparent resulting in S2 dominance over S1. This was assessed using S1 and S2 strain specific MAbs, and it occurred whatever the pattern of inoculation or the rice variety tested. Differences in pathogenicity and virus titre did not account for strain competition, as there was no relation between symptom severity, virus content and serotype of the isolates in Oryza sativa indica cultivars.

Partial characterization of a bovine group A rotavirus with a short genome electropherotype.

A group A rotavirus (ID isolate) recovered from a diarrheic beef calf possessed a short genome electropherotype. This short genome electropherotype was a stable characteristic of the ID isolate as it remained unchanged through 3 passages in gnotobiotic calves or through 19 passages in MA104 cell cultures. Subgroup analysis with monoclonal antibodies in an enzyme-linked immunosorbent assay established that the isolate was a subgroup 1 rotavirus. Neutralization tests demonstrated that this isolate was a distinct serotype from the human group A rotavirus S2 isolate (short genome electropherotype) and the turkey group A rotavirus 174 isolate (semi-short genome electropherotype). The ID isolate was pathogenic for 5- to 21-day-old gnotobiotic calves, inducing diarrhea within 48 h postinoculation.