A total of 23 Newcastle disease virus (NDV) isolates from Bangladesh taken between 2010 and 2012 were characterized on the basis of partial F gene sequences. All the isolates belonged to genotype XIII of class II NDV but segregated into three sub-clusters. One sub-cluster with 17 isolates aligned with sub-genotype XIIIc. The other two sub-clusters were phylogenetically distinct from the previously described sub-genotypes XIIIa, XIIIb and XIIIc and could be candidates of new sub-genotypes; however, that needs to be validated through full-length F gene sequence data. The results of the present study suggest that genotype XIII NDVs are under continuing evolution in Bangladesh.

A virological survey for avian influenza (AI) and Newcastle disease (ND) was conducted in two selected live bird markets (LBMs), namely Kaptan Bazar and Karwan Bazar in Dhaka city, Bangladesh from August 2011 to July 2012. A total of 513 dead chickens were collected. An immune-chromatographic rapid antigen test for Type A influenza virus and both conventional and real time RT-PCR were used for the detection and characterization of AI and ND viruses. All carcasses were first screened by the rapid antigen test kit and 93 were positive for Type A influenza virus. RT-PCR on a representative number of rapid antigen test positive samples (n = 24) confirmed the presence of Type A influenza virus and mostly H5 influenza virus (22 out of 24 tested samples). Influenza rapid test negative samples (n = 420) were subjected to routine necropsy. Heat stress, suffocation and physical injury were the most common cause of mortality (163 cases), followed by ND, suspected to be the cause of 85 deaths. On molecular investigation of these 85 samples, the presence of ND virus was confirmed in 59 and AI virus in 6; 15 were negative for both ND and AI viruses and 5 were unsuitable for investigation. Among the 59 ND confirmed cases 18 also contained AI virus. In summary, out of 513 carcasses 117 (22.81%) contained AI virus and 59 (11.50%) contained ND virus. Eighteen (3.51%) carcasses contained both AI and ND viruses. The findings suggest that both AI and ND should be considered as major threats to the poultry industry. (Bangl. vet.

A real-time reverse transcription -polymerase chain reaction (rRT-PCR) was used for the detection of Newcastle disease virus (NDV) of poultry. A panel of seven known isolates of NDV in the form of allantoic fluid, obtained from a laboratory repository, was used for the development of the test. RNA was extracted from the allantoic fluid with a magnetic processor based automated RNA extraction system. The identity of the reference virus was first reconfirmed by a conventional RT-PCR specific for the Fusion (F) protein gene. Using these RNA, the rRT-PCR protocol was optimized with regard to the reaction mix and thermal profile using published primers and probes specific for M gene. The sensitivity of standardized rRT-PCR was compared to that of the conventional RT-PCR using serial 10-fold dilutions of the RNA of a selected sample. The thermal profile was modified from the published one; the annealing and extension steps were combined to a single step performed at 60ºC. The adopted rRT-PCR successfully amplified M gene from all the seven reference samples with a C T value ranging from 15.28 to 32.68. The rRT-PCR for M gene was 100-fold more sensitive than the conventional RT-PCR for F gene. This is the first report of the use of rRT-PCR for the detection of NDV in Bangladesh. This test will be useful for virological surveillance, particularly for screening NDV in respiratory infections. (Bangl. vet.