High Density Microarray Analysis Reveals New Insights into Genetic Footprints of Listeria monocytogenes Strains Involved in Listeriosis Outbreaks

Listeria monocytogenes, a foodborne bacterial pathogen, causes invasive and febrile gastroenteritis forms of listeriosis in humans. Both invasive and febrile gastroenteritis listeriosis is caused mostly by serotypes 1/2a, 1/2b and 4b strains. The outbreak strains of serotype 1/2a and 4b could be further classified into several epidemic clones but the genetic bases for the diverse pathophysiology have been unsuccessful. DNA microarray provides an important tool to scan the entire genome for genetic signatures that may distinguish the L. monocytogenes strains belonging to different outbreaks. We have designed a pan-genomic microarray chip (Listeria GeneChip) containing sequences from 24 L. monocytogenes strains. The chip was designed to identify the presence/absence of genomic sequences, analyze transcription profiles and identify SNPs. Analysis of the genomic profiles of 38 outbreak strains representing 1/2a, 1/2b and 4b serotypes, revealed that the strains formed distinct genetic clusters adhering to their serotypes and epidemic clone types. Although serologically 1/2a and 1/b strains share common antigenic markers microarray analysis revealed that 1/2a strains are further apart from the closely related 1/2b and 4b strains. Within any given serotype and epidemic clone type the febrile gastroenteritis and invasive strains can be further distinguished based on several genetic markers including large numbers of phage genome, and intergenic sequences. Our results showed that the microarray-based data can be an important tool in characterization of L. monocytogenes strains involved in both invasive and gastroenteritis outbreaks. The results for the first time showed that the serotypes and epidemic clones are based on extensive pan-genomic variability and the 1/2b and 4bstrains are more closely related to each other than the 1/2a strains. The data also supported the hypothesis that the strains causing these two diverse outbreaks are genotypically different and this finding might be important in understanding the pathophysiology of this organism

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Technical Bulletin No. 11

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Technical Bulletin No. 46

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Not AvailableSevere Acute Respiratory Syndrome Corona Virus- 2 (SARS-CoV-2) or coronavirus disease (COVID-19) has been identified as the cause of a pandemic of respiratory illness. It has been declared as a Public Health Emergency of International Concern by the World Health Organization. The reported symptoms include fever, cough, fatigue, pneumonia, headache, diarrhea, hemoptysis, and dyspnea. The human-to-human transmission has been described via droplets, contaminated hands or surfaces. The incubation times ranges between 2-14 days. Early diagnosis, quarantine, and supportive treatments are required to cure patients. Treatments, including antiviral agents, chloroquine and hydroxychloroquine, monoclonal antibodies, and convalescent plasma transfusion have been used for successful treatment of the patients. Preventive measures such as masks, hand hygiene practices, avoidance of public contact, case detection, contact tracing, and quarantines have been discussed as ways to reduce transmission. The pandemic has impacted on the meat industry. The event demands urgent implementation of a multidisciplinary team in a One Health approach to address the present-day challenges at the human-animal-environment interface. We reviewed the literature on the epidemiology, the disease, diagnosis, therapeutics and mitigation strategies of COVID-19. Although many studies are relevant to control the current public emergency, more research is needed to provide valid and reliable ways to manage this kind of public health emergency in both the short- and long-term.Not Availabl

Technical Bulletin No. 39

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