Summary Enteroaggregative Escherichia coli (EAEC), is a diarrhoeagenic human pathogen commonly isolated from patients in both developing and industrialized countries. Pathogenic EAEC strains possess many virulence determinants, which are thought to be involved in causing disease, though, the exact mechanism by which EAEC causes diarrhoea is unclear. Typical EAEC strains possess the transcriptional regulator, AggR, which controls the expression of many virulence determinants, including the attachment adherence fimbriae (AAF) that are necessary for adherence to human gut epithelial cells. Here, using RNA‐sequencing, we have investigated the AggR regulon from EAEC strain 042 and show that AggR regulates the transcription of genes on both the bacterial chromosome and the large virulence plasmid, pAA2. Due to the importance of fimbriae, we focused on the two AAF/II fimbrial gene clusters in EAEC 042 (afaB‐aafCB and aafDA) and identified the promoter elements and AggR‐binding sites required for fimbrial expression. In addition, we examined the organization of the fimbrial operon promoters from other important EAEC strains to understand the rules of AggR‐dependent activation. Finally, we generated a series of semi‐synthetic promoters to define the minimal sequence required for AggR‐mediated activation and show that the correct positioning of a single AggR‐binding site is sufficient to confer AggR‐dependence.

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Coronaviruses are one of the Coronaviridae family in the Nidovirales order. Coronaviruses are small in size (65-125 nm in diameter) and contain a single-stranded RNA as a nucleic material. They are characterized by having crown-like spikes on the virus' outer surface; thus, it is named coronavirus. 1 The coronaviruses are genotypically and serologically divided into four subgroups: α-, β-, γ-, and δ-CoVs. Human CoVs infections are mainly due to α-and β-subgroups like severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV), which belong to β-CoVs. 2 The SARS-CoV-2 virus causing the coronavirus disease 2019 (COVID-19) was classified by the World Health Organization (WHO) as a β-CoV of group 2B. 3 The genetic sequence of SARS-CoV-2 showed more than 80% identity to SARS-CoV and 50% to the MERS-CoV; both originate in bats. 4,5 Presently, COVID-19 patients are considered to be the primary source of infection, as person-to-person transmission occurs predominantly via direct contact or through droplets during coughing or sneezing. 6 Until now, there is no proof that SARS-CoV-2 can be transmitted through aerosols or from mother to baby during pregnancy or childbirth. 6 Hence, there are no available data on the consequences of COVID-19 on the course and outcome of pregnancy; it is crucial to pay more attention to this issue, especially that COVID-19 still appears to be sweeping. Moreover, pregnant mothers are pretty more predisposed to infection by respiratory pathogens and severe pneumonia. 2 | IMMUNOLOGY AND PATHOG ENE S IS OF COVID-19 All coronaviruses have specific genes in ORF1 downstream regions that encode proteins for viral replication, nucleocapsid, and spikes formation, and the structural proteins are encoded by the four structural genes, including spike (S), envelope (E), membrane (M), and nucleocapsid (N) genes. 7 Although the genome of the SARS-CoV-2 has