Biology subjects

Ojha, C. R.

Publications and source records attributed to Ojha, C. R..

2 recordsLinked to original sources

bioRxiv2021

Minor variants of swine H1N1 influenza viruses with enhanced polymerase activity and HA stability promote airborne transmission in ferrets

Understanding how animal influenza A viruses (IAVs) acquire airborne transmissibility in humans and ferrets is needed to prepare for and respond to pandemics. Here, we investigated in ferrets the replication and transmission of swine H1N1 isolates P4 and G15, whose majority population had decreased polymerase activity and poor HA stability, respectively. For both isolates, a minor variant was selected and transmitted in ferrets. Polymerase-enhancing variant PA-S321 airborne-transmitted and propagated in one ferret. HA-stabilizing variant HA1-S210 was selected in all G15-inoculated ferrets and was transmitted by contact and airborne routes. With an efficient polymerase and a stable HA, the purified minor variant G15-HA1-S210 had earlier and higher peak titers in inoculated ferrets and was recovered at a higher frequency after airborne transmission than P4 and G15. Overall, HA stabilization played a more prominent role than polymerase enhancement in the replication and transmission of these viruses in ferrets. The results suggest pandemic risk-assessment studies may benefit from deep sequencing to identify minor variants with human-adapted traits. IMPORTANCEDiverse IAVs circulate in animals, yet few acquire the viral traits needed to start a human pandemic. A stabilized HA and mammalian-adapted polymerase have been shown to promote the adaptation of IAVs to humans and ferrets (the gold-standard model for IAV replication, pathogenicity, and transmissibility). Here, we used swine IAV isolates of the gamma lineage a model to investigate the importance of HA stability and polymerase activity in promoting replication and transmission in ferrets. These are emerging viruses that bind to both -2,6- and -2,3-linked receptors. Using isolates containing mixed populations, a stabilized HA was selected within days in inoculated ferrets. An enhanced polymerase was also selected and propagated after airborne transmission to a ferret. Thus, HA stabilization was a stricter requirement, yet both traits promoted transmissibility. Knowing the viral traits needed for pandemic potential, and the relative importance of each, will help identify emerging viruses of greatest concern.

microbiology↗

bioRxiv2019

ZIKA VIRUS INFECTION DURING PREGNANCY AND INDUCED BRAIN PATHOLOGY IN BECLIN1-DEFICIENT MOUSE MODEL

We investigated the role of the autophagy protein, Beclin1, in the replication and disease of Zika virus (ZIKV) in pregnant dams and their offspring using Beclin1-deficient (Atg6+/-) and wild-type (Atg6+/+) mouse model infected with the Honduran (R103451), Puerto Rican (PRVABC59), and the Uganda (MR766) strains of ZIKV. Pregnant dams infected subcutaneously at embryonic stage (E)9 showed viral RNA in serum harvested at E13 and in various organs removed postmortem at E17. Subcutaneous infections with ZIKV also showed the vertical transmission of ZIKV from the placenta to embryos removed postmortem at E17. From the three isolates, R103451-infected Atg6+/- dams had the lowest mortality rate while 30 % of their offspring containing the hemizygous beclin1 allele (Atg6+/-) were smaller in size and had smaller and underdeveloped brain. Growth impairment in the pups became noticeable after two weeks post-birth. After 21-days, pups were sacrificed and brain tissues removed postmortem showed expression of the envelope (E) and the non-structural (NS)-1 proteins, along with signs of neuronal injury, despite an absence in viral RNA detection. A significant decrease in the mRNA expression levels of the insulin-like growth factor-1 (IGF-1) by 8-fold and a decrease in the mRNA expression levels of several microcephaly related genes along with an increase in the secretion of several inflammatory molecules may have contributed to the observed phenotype. Since autophagy regulates cytokines and chemokines production, a dysregulation in this pathway may have further exacerbated the pathology of ZIKV. IMPORTANCEPups delivered from ZIKV-infected dams showed significant growth impairments in the body and the brain. We believe that the reduction in insulin growth factor together with the increase secretion of inflammatory molecules may have triggered neuronal injury and the downregulation of the microcephalic genes, while reduced expression of the autophagy protein, Beclin1 further exacerbated the pathology. Although the mechanism is still unknown, the autophagy pathway seems to play a key role in ZIKV pathology. It is therefore of great significance to study the role of autophagy during viral infection with the goal to identify potential targets for anti-ZIKV therapeutic intervention.

immunology↗