The present research work was carried out to isolate and identify Newcastle disease virus (NDV) by using haemagglutination inhibition (HI) test and reverse transcription-polymerase chain reaction (RT-PCR) assay. A total of 160 clinical (blood, tracheal and cloacal swabs) and post-mortem (brain, lung, colon and spleen) samples were collected from chickens of two field outbreaks of Newcastle disease (ND) in 2006, one in a broiler (Cobb-500) farm of Mymensingh district and other one in a layer (Sonali) farm of Gazipur district. All the samples were inoculated onto 10-day-old embryonated chicken eggs through allantoic sac route and in the chicken embryo fibroblasts (CEFs) cell culture. The allantoic fluid (AF) of the dead embryos and the infected culture fluid (ICF) of the CEF were harvested at 48 and 96 hours of post-infection, respectively. The HI and RT-PCR were employed to detect NDV in tissue homogenates of all the clinical and post-mortem samples as well as laboratory samples (AF and ICF). Among the clinical samples, virus isolation rate was found higher from tracheal swab (90%) compared to those of cloacal swab (85%) and serum (65%). On the other hand, among the four different types of post-mortem samples, virus isolation rate was found higher in spleen (100%) compared to those of lungs (80%), colon (60%), and brain (80%) samples. In CEF cell culture system, the rate of virus isolation from all the aforesaid samples was found 100% with the exception of serum samples. The isolation rate of NDV was higher in CEF culture system (93.8%) compared to that of avian embryos (80%). Among the clinical and post-mortem samples, inoculum of only cloacal swab and colon showed HA and HI activities. The anti-NDV hyperimmune serum revealed complete inhibition of the 4 haemagglutination unit of each isolate of viruses isolated from broiler and layer chickens present in the laboratory samples (AF and ICF). The NDV specific primers used in the direct RT-PCR for genome detection of NDV showed equal sensitivity and specificity with the RNA extracted from the clinical, post-mortem and laboratory samples (AF and ICF) as with the genomic RNA of reference NDV. Higher rate of detection of NDV was recorded with RT-PCR assay than HI test. Therefore, the molecular method (RT-PCR) can be introduced for rapid and confirmatory detection of NDV from any form of outbreak of ND in the field level of Bangladesh.

Escherichia coli from 10 different biological and environmental sources were isolated and characterized in the Department of Microbiology and Hygiene, Bangladesh Agricultural University, Mymensingh during the period from January to May 2007. A total of 100 samples, 10 from each of human feces and urine, rectal swab of cattle, sheep and goat, cloacal swab of chicken, duck and pigeon, drain sewage and soil were collected aseptically and subjected to primary isolation by propagating in nutrient broth followed by culture on different agar media. Gram's staining and hanging drop techniques were also performed. Biochemical properties of the isolates were studied and reaction in TSI agar slant was also observed. Pathogenicity of 10 representative E. coli isolates, one from each source were determined by lethality assay in 12 day-old embryonated eggs, in day-old chicks and in day-old suckling mice models. E. coli was isolated successfully from all the samples. All the E. coli isolates were found to produce bright pink colonies on MacConkey agar, yellowish green colonies surrounded by an intense yellow green zone on BG agar and characteristic metallic sheen colonies on the EMB agar. In case of E. coli isolated from cattle, slight variation in colony character on EMB agar was observed showing greenish red colonies with faint metallic sheen. In Gram's staining technique, all the isolates were pink coloured, small rod shaped Gram negative bacilli and in the hanging drop technique they were motile. Reactions in TSI agar slant revealed yellow slant and butt with gas but no hydrogen sulphide production. Almost all the E. coli isolates fermented dextrose, maltose, lactose, sucrose and mannitol with the production of both acid and gas except E. coli isolated from drain sewage which did not ferment maltose and isolates from pigeon showed less production of acid and gas during sucrose fermentation. The results of Catalase, MR and indole test of the E. coli isolates were positive but V-P test was negative. In the embryo lethality assay, E. coli isolates from chicken, pigeon, duck, human urine, cattle, sheep and goats were virulent causing 33.33-100% death of the embryo except isolates from human faeces and drain sewage which were moderately virulent and that from soil which was avirulent. E. coli isolate of chicken origin found to be more virulent which caused 100% death of the embryos. Most of the embryos died between day-1 and day-2 PI. Chick lethality assay indicated that all the E. coli isolates were virulent as the mortality rate was more than 50%. In mice lethality assay, all the E. coli isolates were in the killer group causing cent percent death of mice within 10 to 42 h following inoculation. Among these three lethality assay models, avian embryo lethality assay was found to be most suitable to discriminate between virulent and avirulent isolates compared to day-old chick lethality assay and day-old suckling mice lethality assay where inconsistent results were observed. In conclusion, our result showed that E. coli...

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. The MIC of the cloxacillin for 5 MRSA strains were ≥32 (µg/ml), for 1 MRSA strain was ≥ 128(µg/ml) and for another 4 MRSA strains were above ≥128 (µg/ml). Antimicrobial susceptibility test of the isolated organisms were done by disc diffusion method. On antibiotic susceptibility test, MRSA strains showed 100% resistant against penicillin, oxacillin, cloxacillin and amoxycillin. Cent per cent susceptibility of MRSA was found against vancomycin, ciprofloxacin, erythromycin, fusidic acid and rifampicin.

The ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is having a disastrous impact on global health. Recently, several studies examined the potential of vitamin D to reduce the effects of SARS-CoV-2 infection by modulating the immune system. Indeed, vitamin D has been found to boost the innate immune system and stimulate the adaptive immune response against SARS-CoV-2 infection. In this review, we provide a comprehensive update of the immunological mechanisms underlying the positive effects of vitamin D in reducing SARS-CoV-2 infection as well as a thorough survey of the recent epidemiological studies and clinical trials that tested vitamin D as a potential therapeutic agent against COVID-19 infection. We believe that a better understanding of the histopathology and immunopathology of the disease as well as the mechanism of vitamin D effects on COVID-19 severity will ultimately pave the way for a more effective prevention and control of this global pandemic.