Biology subjects

Kafle, S.

Publications and source records attributed to Kafle, S..

4 recordsLinked to original sources

bioRxiv2026

Interferon-α and -β subtypes have temporally distinct roles in containing viral spread and protecting vital organs.

Type I interferons (IFN-Is), including a single IFN-{beta} and over a dozen IFN-s, induce the anti-viral state. In vitro, IFN-{beta} transcription requires the assembly of the "enhanceosome" composed of the constitutive transcription factors NF-{kappa}B and AP-1, and either constitutive IRF3 or IFN-I-inducible IRF7. IRF3 and IRF7 transcribe mouse IFN-4 and human IFN-1/13. Only IRF7 transcribes other IFN-s. How IFN-I subtype multiplicity and their differential constitutive/IFN-I-inducible versus only IFN-I-inducible transcription help control viruses in vivo remains unknown. Using novel genetically modified mice, we demonstrate that most or all IFN-I subtypes, regardless of their transcriptional control, are necessary to curb the systemic dissemination of lymph-borne ectromelia virus (ECTV) but do not necessarily suppress ECTV or West Nile Virus (WNV) replication in the liver or the brain, or promote survival to their infection. Individually, the most critical IFN-I subtype to survive ECTV and WNV infections is IFN-{beta}. IFN-4 potentiates IFN-{beta} but is not essential. PRDII, the IFN-{beta} promoters NF-{kappa}B binding site, which is required for enhanceosome assembly, is dispensable for in vivo IFN-{beta} production but complements IRF7-IFN-{beta} transcription to restrain ECTV and WNV. IFN-{beta} alone protects IFN--deficient mice from ECTV but not from WNV lethality. Control of WNV replication in the brain successively requires IFN-, IFN-{beta}, and then PRDII-dependent IFN-{beta}, suggesting that brain protection requires IFN-I production by various cell types and pathways. Thus, contrary to the prevailing view, in vivo, IFN-{beta} does not function earlier than IFN-, and IFN-I subtypes non-redundantly cooperate to restrain viruses in the periphery and in vital organs.

immunology↗

bioRxiv2026

Pathogenesis of H5N1 Clade 2.3.4.4b in dry Jersey cows following intramammary inoculation shows within-host compartmentalization

Dairy cattle have emerged as a prolific amplifying host for highly pathogenic avian influenza virus (HPAIV) H5N1 clade 2.3.4.4b and a new source for cross-species and zoonotic transmission. Independent introductions of H5N1 with unclear exposure routes have been reported in several dairy herds across the U.S. These events escalate the pandemic potential of HPAIV H5N1 as transmission within and between mammalian species present opportunities for mammalian adapted H5N1 viruses to emerge. Although more than 1000 herds have been infected, bovine H5N1 influenza virus pathogenesis, transmission, and evolution in dairy cattle remains not well characterized. Working with H5N1-infected lactating cattle in high containment has been a major challenge due to the required infrastructure and logistics associated with housing, husbandry, and waste management for this model. Thus, developing alternative bovine models that maintain biological relevance while reducing operational complexity is warranted. Here, we evaluate the susceptibility of lactating Jersey cattle in the dry-off period, and characterize the effect of inoculation dose on the mammary pathogenicity of HPAIV H5N1 genotype B3.13. The results of this study demonstrate that dairy cows 21 days into the dry-off period are highly susceptible to HPAIV H5N1, recapitulating the severe clinical and pathological outcomes observed in infected lactating cows under experimental conditions and in field cases. We also observed an association between virus dose and the onset and severity of mastitis in individual udder-quarters. Overall, this study demonstrates that dry cows can provide a feasible model to study H5N1 virology, pathology, and humoral immunology in dairy cows.

microbiology↗

bioRxiv2025

Pathogenicity and transmissibility of bovine-derived HPAI H5N1 B3.13 virus in pigs

Since the first emergence of highly pathogenic avian influenza (HPAI) H5N1 viruses in dairy cattle, the virus has continued to spread, reaching at least 17 states and at least 970 dairy herds in the United States. Subsequently, spillovers of the virus from dairy cattle to humans have been reported. Pigs are an important reservoir in influenza ecology because they serve as a mixing vessel in which novel reassortant viruses with pandemic potential can be generated. Here, we show that oro-respiratory infection of pigs resulted in productive replication of a bovine-derived HPAI H5N1 B3.13 virus. Infectious virus was mainly identified in the lower respiratory tract of principal infected pigs, and sero-conversion was observed in most of the principal pigs at later time points. In one animal, we detected the emergence of a mutation in hemagglutinin (HA) previously associated with increased affinity for "mammalian-type" 2,6-linked sialic acid receptors, but this mutation did not reach consensus levels. Sentinel contact pigs remained sero-negative throughout the study, indicating lack of transmission. The results support that pigs are susceptible to a bovine-derived HPAI H5N1 B3.13 virus, but this virus did not replicate as robustly in pigs as mink-derived HPAI H5N1 and swine-adapted influenza viruses.

microbiology↗

bioRxiv2024

Outcome of H5N1 clade 2.3.4.4b virus infection in calves and lactating cows

In March 2024, highly pathogenic avian influenza virus (HPAIV) clade 2.3.4.4b H5N1 infections in dairy cows were first reported from Texas, USA. Rapid dissemination to more than 190 farms in 13 states followed. Here, we provide results of two independent clade 2.3.4.4b experimental infection studies evaluating (i) oronasal susceptibility and transmission in calves to a US H5N1 bovine isolate genotype B3.13 (H5N1 B3.13) and (ii) susceptibility of lactating cows following direct mammary gland inoculation of either H5N1 B3.13 or a current EU H5N1 wild bird isolate genotype euDG (H5N1 euDG). Inoculation of the calves resulted in moderate nasal replication and shedding with no severe clinical signs or transmission to sentinel calves. In dairy cows, infection resulted in no nasal shedding, but severe acute mammary gland infection with necrotizing mastitis and high fever was observed for both H5N1 genotypes/strains. Milk production was rapidly and drastically reduced and the physical condition of the cows was severely compromised. Virus titers in milk rapidly peaked at 108 TCID50/mL, but systemic infection did not ensue. Notably, adaptive mutation PB2 E627K emerged after intramammary replication of H5N1 euDG. Our data suggest that in addition to H5N1 B3.13, other HPAIV H5N1 strains have the potential to replicate in the udder of cows and that milk and milking procedures, rather than respiratory spread, are likely the primary routes of H5N1 transmission between cattle.

microbiology↗