Galliez, R. M. | bioRxiv Science

bioRxiv2024

Unique RNA replication characteristics and nucleocapsid protein expression may explain differences in the replication capacity of SARS-COV-2 lineages.

COVID-19 pandemic in Brazil was characterized by the sequential circulation of the SARS-CoV-2 lineages B.1.1.33, and variants Zeta (P.2), Gamma (P.1/P.1.*), Delta (B.1.617.2/AY.*), and Omicron (BA.*). Our research aimed to compare the biological traits of these lineages and variants by analyzing aspects of viral replication including binding, entry, RNA replication, and viral protein production. We demonstrated that the replication capacity of these variants varies depending on the cell type, with Omicron BA.1 exhibiting the lowest replication in the human pulmonary cells. Additionally, the nucleocapsid proteoforms generated during infection exhibit distinct patterns across variants. Our findings suggest that factors beyond the initial stages of virus entry influence the efficiency of viral replication among different SARS-CoV-2 variants. Thus, our study underscores the significance of RNA replication and the role of nucleocapsid proteins in shaping the replicative characteristics of SARS-CoV-2 variants. Author summaryThe COVID-19 pandemic was characterized by the emergence of different viral variants that presents specific properties such as response to antibodies, pathogenicity and detection by diagnostic tests. The circulation of these variants presented a particular pattern depending on the global geographic regions. Despite the cessation of the pandemic, as officially declared by the World Health Organization in 2023, new viral variants continue to emerge while aspects of the virus-cell interaction that contribute to the replication of these variants have not yet been completely understood. In our study, we compared the biological characteristics of SARS-CoV-2 variants that circulated in Brazil during the pandemic, verifying aspects of entry, viral replication and production of viral RNA and proteins. Our results indicate that Omicron BA.1 variant has reduced replication and protein production in human lung cells. We also observed that the viral nucleocapsid protein presents proteoforms that vary according to the variant. These differences could help to explain the differences observed in viral replication in human pulmonary cells.

microbiology↗

bioRxiv2023

Lessons from a multilaboratorial task force for diagnosis of a fatal toxoplasmosis outbreak in captive primates in Brazil

As exemplified by the Coronavirus Disease 2019 (COVID-19) pandemic, infectious diseases may emerge and spread rapidly, often causing serious economic losses and public health concerns. In fact, disease outbreaks have become increasingly common, especially those of zoonotic origin. The Brazilian Ministry of Health is responsible for national epizootic surveillance. However, the systems focus primarily on diseases affecting humans has led to the neglect of other zoonotic diseases. In this report, we present an integrated investigation of an outbreak that occurred during the first year of the COVID-19 pandemic among captive neotropical primates housed at a primatology center in Brazil. After presenting a range of non-specific clinical signs, including fever, prostration, inappetence, and abdominal pain, ten primates from five different species died within approximately four days. Despite the state of health emergency due to the pandemic, a network of volunteer researchers was established to investigate the outbreak. A wide range of high-resolution techniques was used for different pathogens, including SARS-CoV-2 (RTq-PCR, ELISA and IHC), Toxoplasma gondii (IHC and IFA) and Escherichia coli (IFA), as well as a portable Metagenomic Sequencing utilizing Nanopore Technology. Within a span of four days after necropsies, we successfully identified T. gondii as the causative agent of this outbreak. This case highlights some of the obstacles faced with the current Brazilian surveillance system, which is still limited. A cross-platform interdisciplinary investigation could be a possible model for future epizootic investigations in non-human animals. Author summaryThe Brazilian epizootic surveillance system, under the regulation of the Ministry of Health, has been established to address a national list of compulsory notifiable diseases. However, focusing mainly on the risks to humans causes other zoonoses to be neglected. Here we present an outbreak that occurred during the first year of the COVID-19 pandemic that affected eleven neotropical primates (NP) belonging to six different species. Within four days of exhibiting a range of non-specific clinical signs, including fever, prostration, inappetence, and abdominal pain, ten NPs died. Despite testing negative for pathogens included in the national surveillance policy, a collaborative group of researchers investigated the outbreak in detail. Using integrated diagnostic techniques, we identified Toxoplasma gondii as the causative agent four days after necropsy. Toxoplasmosis causes devastating acute death outbreaks in neotropical primates and is currently absent in the national guidelines. This unified effort proved the effectiveness of a multidisciplinary collaborative surveillance network in facilitating precise diagnoses.

microbiology↗