Biology subjects

Kondabagil, K.

Publications and source records attributed to Kondabagil, K..

4 recordsLinked to original sources

bioRxiv2025

Effect of carrier droplet size and shape at different viral loads on virus stability during environmental drying

In the aftermath of the COVID-19 pandemic, airborne transmission has been identified as a significant factor in disease spread. However, there have been very few direct comparisons of virus viability in airborne droplets versus those deposited on surfaces or fomites. This study compares the viability of the enveloped Phi6 virus and two non-enveloped viruses (T4 and MS2) in droplets on hydrophobic and hydrophilic surfaces at 25{degrees}C and 45%-55% relative humidity. The former results in spherical droplets similar to airborne droplets, while the latter pertains to spreading droplets comparable to a fomite state. Our research highlights the influence of various physical factors of the carrier droplet--such as its shape and size--as well as the type and concentration of the virus on its viability during the drying process. We found that, at a fixed volume, virus viability decreased with droplet size in spherical droplets, while high initial viral concentrations ([~] 105 pfu/{micro}L) improved survival on fomites. This suggests that fomites from individuals with high viral loads pose a greater risk of infection. Overall, droplets of a specific volume are more viable in the air than on surfaces. Smaller airborne droplets may have decreased viability but can linger longer and penetrate deeper into the respiratory tract. When viral loads are high, its comparable persistence in both spherical and flat droplets increases the risk of fomite transmission. IMPORTANCEUnderstanding the roles of airborne and fomite transmission in respiratory diseases is essential for planning effective containment measures and resource allocation. Among the various factors that influence the spread of infection, the survival of viruses in drying droplets plays a critical role in disease transmission. In our study, we compare the viability of viruses in spherical droplets, which represent airborne transmission, and flat droplets, which represent fomite transmission. Our results indicate that virus viability is consistently higher in spherical droplets than in flat droplets when dried under similar conditions. However, for high virus loads, the difference in virus survival is significantly lower. Therefore, during an outbreak, it is important to monitor both the number of new infections and the viral load of infected individuals, as those with higher viral loads are more likely to spread the infection through both modes of transmission.

microbiology↗

bioRxiv2024

The life history traits of phages in a cocktail determine coinfection dynamics and efficacy

Phage cocktails are preferred over single phages for efficacious and broader-spectrum therapy. An ideal phage cocktail should have a minimum number of phages with efficient infection kinetics and delay the emergence of resistance in bacterial populations. This study examined population dynamics of the common host and combinations of two phages (N4, KKE5P, and Ec_YwIITB1) through experimental and modeling approaches to gaining insights into how phage life history traits influence the outcome of infection in the short-term of approximately an infection cycle, and whether it is informative for developing efficacious cocktails. We tested the killing efficacy of a cocktail containing two divergent phages (N4 and Ec_YwIITB1) with similar adsorption rates but differed in their latency period. Because of the shorter latency period, phage N4 dominated under all conditions tested. The cocktail essentially behaves as a single phage. When two phages (N4 and KKE5P), with similar adsorption rates and latency periods but targeted different host receptors were used, it not only resulted in the efficient replication of both phages but also improved the suppression of the emergence of resistance when compared to the N4 and Ec_YwIITB1 combination, thus behaving like an ideal cocktail. The ODE-based mathematical model demonstrated predictive capabilities consistent with experimental observations and offered insights into infection dynamics. The model may aid in phage selection and optimizing cocktail formulation based on phage life history traits. This study highlights the need for thorough characterization of phage growth parameters and informed combinations of phages, as random combinations could lead to undesirable outcomes.

microbiology↗

bioRxiv2024

The low abundance of antimicrobial resistance genes (ARGs) in bacteriophages and their transfer bottlenecks limit the ability of phages to contribute to the spread of ARGs

The role of bacteriophages in the spread of antimicrobial resistance genes (ARGs) has been debated over the past decade. Several questions regarding the ARG dissemination potential of bacteriophages remain unanswered. For example, what is the frequency of acquisition of ARGs in phages? Are phages selective in acquiring the ARGs compared to other host genes? What is the predominant mechanism of transferring ARGs to phages? To address these questions, we thoroughly analyzed the available phage genomes, viromes, temperate phage, and prophage sequences for the presence of all known ARGs. Out of the 38,861 phage genome sequences we analyzed, only 182 phages contained a total of 314 ARGs. Interestingly, a few of the Streptococcus and Acinetobacter phages were found to carry an ARG cluster with four or more genes. One of the uncharacterized Myoviridae phages was found to carry the entire vancomycin operon. Furthermore, based on the presence of lysogenic marker sequences, the terminal location of ARGs on phage genomes, and complete ARG clusters transferred to phages, we suggest that ARGs are predominantly acquired from hosts by temperate phages via specialized transduction. The close association of most phage ARGs with lysogenic markers and mobile genetic elements (MGEs) also points towards specialized transduction as a potent mechanism of acquisition of ARGs by phages. Our study further suggests that the acquisition of ARGs by phages occurs by chance rather than through a selective process. Taken together, the limited presence of ARGs in phages, alongside various transfer bottlenecks, significantly restricts the role of phages in the dissemination of ARGs.

microbiology↗

bioRxiv2024

Mimivirus encodes an essential MC1-like non-histone architectural protein involved in DNA condensation

The first giant virus discovered, Acanthamoeba polyphaga mimivirus (APMV), has a 1.2 Mb dsDNA genome organized as genomic fiber within the capsid. This fiber is comprised of a proteinaceous shell of [~]30 nm diameter that encloses the folded DNA. Surprisingly, for the assembly of the enormous genome of APMV, no DNA condensing protein has been reported to date. Our analysis of the uncharacterized packaged protein complement of Mimivirus led to the identification of a putative DNA-bending archaeal MC1 domain in a hypothetical protein (gp275) coded by the R252 gene. Gene knock-out analysis shows that gp275 is critical for viral multiplication. Biochemical and microscopic characterization further demonstrates the compaction of DNA upon binding to gp275. Together, this study suggests that gp275 is an MC1-like architectural protein involved in the organization of the genomic DNA within the capsid of Mimivirus.

molecular biology↗