Viral diagnosis in Indian livestock using customized microarray chips

Bioinformatics and Microarray-Based Technologies to Viral Genome Sequence Analysis

Identification of microbial pathogen is an important event which lead to diagnosis, treatment, and control of infections produce by them. The high-throughput technology like microarray and new-generation sequencing machine are able to generate huge amount of nucleotide sequences of viral and bacterial genome of both known and unknown pathogens. Few years ago it was the DNA microarrays which had great potential to screen all the known pathogens and yet to be identified pathogen simultaneously. But after the development of a new generation sequencing, technologies and advance computational approach researchers are looking forward for a complete understanding of microbes and host interactions. The powerful sequencing platform is rapidly transforming the landscape of microbial identification and characterization. As bioinformatics analysis tools and databases are easily available to researchers, the enormous amount of data generated can be meaningfully handled for better understanding of the microbial world. Here in this chapter, we present commentary on how the computational method incorporated with sequencing technique made easy for microbial detection and characterization.

A novel multiplex PCR-electronic microarray assay for rapid and simultaneous detection of bovine respiratory and enteric pathogens

Respiratory and enteric diseases continue to be two major causes of economic losses to the cattle industry worldwide. Despite their multifactorial etiology, the currently available diagnostic tests for bovine respiratory disease complex (BRDC) and bovine enteric disease (BED) are single-pathogen-tests. DNA microarray when combined with multiplex polymerase chain reaction (PCR) is a powerful tool in detection and differentiation of multiple pathogens in a single sample. This study reports development and initial validation of two independent highly sensitive and specific multiplex PCR-electronic microarray assays, one for the detection and differentiation of pathogens of the BRDC and the other for detection and differentiation of pathogens of the BED. The BRDC multiplex PCR-microarray assay was able to detect and differentiate four bacteria (Mannheimia haemolytica, Histophilus somni, Pasteurella multocida, and Mycoplasma bovis) and five viruses [bovine parainfluenza virus-3, bovine respiratory syncytial virus, bovine herpesvirus-1, bovine coronavirus (BCoV), and bovine viral diarrhea virus (BVDV)] associated with BRDC. The BED multiplex PCR- microarray- assay was able to detect and differentiate four bacteria (Clostridium perfringens, Escherichia coli, Salmonella enterica Dublin, and Salmonella enterica Typhimurium), three protozoa (Eimeria zuernii, Eimeria bovis, and Cryptosporidium parvum), and four viruses (bovine torovirus, bovine rotavirus, BCoV, and BVDV) associated with the BED. Both assays detected their respective targets individually or in combination when present. The limit-of-detection of each assay at the PCR amplification and DNA microarray levels was determined using previously titrated laboratory amplified target pathogens or using quantified synthetic nucleotides. Both assays showed very high analytical sensitivity and specificity, and were validated using a limited number of clinical samples. The BRDC and BED multiplex PCR- microarray-assays developed in this study, with further clinical validation, could be used in veterinary diagnostic laboratories for the rapid and simultaneous identification of pathogens to facilitate quick and accurate decision making for the control and treatment of these two economically important disease complexes. Furthermore, these assays could be very effective tools in epidemiological studies as well as for screening of healthy animals to identify carriers that may potentially develop BRDC or BED.