PreS1 Mutations Alter the Large HBsAg Antigenicity of a Hepatitis B Virus Strain Isolated in Bangladesh

Mutations in the hepatitis B virus (HBV) genome can potentially lead to vaccination failure, diagnostic escape, and disease progression. However, there are no reports on viral gene expression and large hepatitis B surface antigen (HBsAg) antigenicity alterations due to mutations in HBV isolated from a Bangladeshi population. Here, we sequenced the full genome of the HBV isolated from a clinically infected patient in Bangladesh. The open reading frames (ORFs) (P, S, C, and X) of the isolated HBV strain were successfully amplified and cloned into a mammalian expression vector. The HBV isolate was identified as genotype C (sub-genotype C2), serotype adr, and evolutionarily related to strains isolated in Indonesia, Malaysia, and China. Clinically significant mutations, such as preS1 C2964A, reverse transcriptase domain I91L, and small HBsAg N3S, were identified. The viral P, S, C, and X genes were expressed in HEK-293T and HepG2 cells by transient transfection with a native subcellular distribution pattern analyzed by immunofluorescence assay. Western blotting of large HBsAg using preS1 antibody showed no staining, and preS1 ELISA showed a significant reduction in reactivity due to amino acid mutations. This mutated preS1 sequence has been identified in several Asian countries. To our knowledge, this is the first report investigating changes in large HBsAg antigenicity due to preS1 mutations

Isolation and identification of Clostridium chauvoei from cattle in Mymensingh

Black quarter (BQ), caused by Clostridium chauvoei, is an economically important, highly infectious bacterial disease of cattle, goat and sheep. The present study was conducted to isolate and identify the causal agent of BQ from field cases. A total of 32 samples from necropsied areas of cattle presented to the Teaching Veterinary Hospital, Bangladesh Agricultural University were collected. The samples were subjected for bacteriological culture followed by identification through a series of conventional bacteriological techniques, staining properties and biochemical tests. The bacteria were cultured in anaerobic condition using candle jar. Morphological characters of bacteria were observed after Gram stain. The suspected samples were subjected for several passages in liver infusion broth to get pure culture. On neomycin blood agar, the bacteria showed hemolysis. Based on the cultural and staining characteristics and biochemical tests, 4 (12.5%) out of 32 samples were confirmed as Cl. chauvoei. It is concluded that Cl. chauvoei has been successfully isolated and identified from BQ affected cattle. [Fundam Appl Agric 2019; 4(1.000): 649-654

Isolation and Characterization of Multidrug-Resistant Escherichia coli and Salmonella spp. from Healthy and Diseased Turkeys

Diseases caused by Escherichia coli (E. coli) and Salmonella spp. can negatively impact turkey farming. The aim of this study was to isolate and characterize multidrug-resistant (MDR) E. coli and Salmonella spp. in healthy and diseased turkeys. A total of 30 fecal samples from healthy turkeys and 25 intestinal samples from diseased turkeys that died of enteritis were collected. Bacterial isolation and identification were based on biochemical properties and polymerase chain reaction (PCR). Antibiogram profiles were determined by disk diffusion. The tetracycline-resistance gene tetA was detected by PCR. All samples were positive for E. coli. Only 11 samples (11/30; 36.67%) were positive for Salmonella spp. from healthy turkeys, whereas 16 (16/25; 64%) samples were positive for Salmonella spp. from diseased turkeys. E. coli isolated from diseased turkeys showed higher resistance to levofloxacin, gentamicin, chloramphenicol, ciprofloxacin, streptomycin, and tetracycline. Salmonella spp. isolated from healthy turkeys exhibited higher resistance to gentamicin, chloramphenicol, ciprofloxacin, streptomycin, imipenem, and meropenem. All E. coli and Salmonella spp. from both healthy and diseased turkeys were resistant to erythromycin. Salmonella spp. from both healthy and diseased turkeys were resistant to tetracycline. Multidrug resistance was observed in both E. coli and Salmonella spp. from diseased turkeys. Finally, the tetA gene was detected in 93.1% of the E. coli isolates and in 92.59% of the Salmonella spp. isolates. To the best of our knowledge, this is the first study to isolate and characterize tetA-gene-containing MDR E. coli and Salmonella spp. from healthy and diseased turkeys in Bangladesh. Both microorganisms are of zoonotic significance and represent a significant public health challenge

Prevalence and characteristics of Shiga-toxin producing Escherichia coli (STEC) isolated from beef slaughterhouse

Objective: Shiga-toxin producing Escherichia coli (STEC) is the most important foodborne bacterial pathogen worldwide and the bovine animals are assumed as a reservoir of this pathogen. The present study was conducted to assess the role of bovine animals as the source of STEC. Materials and methods: To assess the role of bovine animals as the source of STEC, we examined 100 samples (50 rectal swab and 50 beef samples) collected from the local beef slaughterhouses by cultural, morphological, biochemical tests and polymerase chain reaction. Finally, the drug resistance pattern of isolated organisms has been examined. Result: In the preliminary screening by polymerase chain reaction (PCR), E. coli was more prevalent in rectal swab (n=21/50) than beef samples (n=16/50). Among 39 isolated E. coli, 10 isolates were confirmed as STEC (Rectal swab=7, Beef=3) by PCR, where stx2 gene (n=7/10) was predominant than stx1 gene (n=3/10). Remaining 29 isolates did not react to stx primers in PCR. Presence of STEC in beef samples was significantly associated with the fecal contamination at P≤0.1 (0.074818) in Pearsons correlation coefficient method. In addition, most of the isolated STEC strains were resistant to one or more commonly used antimicrobials in the country. Conclusion: The bovine animals and its products could be an important source of multidrug-resistant STEC in the country. [J Adv Vet Anim Res 2018; 5(2.000): 218-225

Prevalence and molecular detection of the causal agents of sub-clinical mastitis in dairy cows in Sirajganj and Pabna districts, Bangladesh

Objective: The present research work was undertaken with the objectives to investigate the prevalence and molecular detection of the causal agents of sub-clinical mastitis (SCM) in cows at milk shed areas in Sirajganj and Pabna districts, Bangladesh. Materials and methods: A total of 300 milk samples were randomly collected from Baghabari milk shed areas of Sirajganj and Pabna districts. The milk samples were subjected for California Mastitis Test (CMT) for identifying SCM. Total 81 positive samples were then used for the isolation and identification of associated bacteria and fungi using conventional microbiological examination and biochemical tests, followed by confirmation by polymerase chain reaction (PCR) using specific primers. Besides, universal primers were used for amplification and sequencing of PCR products where specific primers were not used. Results: The overall prevalence of SCM was 51% (n=153/300). Based on bacteriological examination and biochemical tests, several bacteria were identified in this study; the orgnaisms included Staphylococcus sp. (45.68%), Streptococcus uberis (14.81%), Escherichia coli (9.88%), Proteus sp. (19.75%), Salmonella sp. (1.23%), Acinetobacter sp. (7.41%), and fungus (1.23%). PCR technique confirmed the bacteria as Staphylococcus aureus (279-bp), Streptococcus uberis (884-bp), E. coli (16SrRNA 585-bp, stx1 606-bp, rfbO157 497-bp) and Salmonella sp. (Inv-A gene796-bp). Conclusion: This study reveals that SCM in dairy cattle is persisting in Sirajganj and Pabna districts of Bangladesh. Hygienic practices should be improved, and providing technical intereventions may reduce the rate of SCM in the study areas. [J Adv Vet Anim Res 2017; 4(4.000): 378-384

Complete Genome Sequence of a Precore-Defective Hepatitis B Virus Genotype D2 Strain Isolated in Bangladesh

Hepatitis B virus (HBV) genomic mutations affect viral replication, disease progression, and diagnostic and vaccination efficiency. There is limited information regarding characterization and mutational analysis of HBV isolated in Bangladesh. Here, we report the complete nucleotide sequence of a precore-defective HBV genotype D2 strain isolated in Bangladesh