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Conserved Rotavirus NSP5 and VP2 Domains Interact and Affect Viroplasm.

ABSTRACT: One step of the life cycle common to all rotaviruses (RV) studied so far is the formation of viroplasms, membrane-less cytosolic inclusions providing a microenvironment for early morphogenesis and RNA replication. Viroplasm-like structures (VLS) are simplified viroplasm models consisting of complexes of nonstructural protein 5 (NSP5) with the RV core shell VP2 or NSP2. We identified and characterized the domains required for NSP5-VP2 interaction and VLS formation. VP2 mutations L124A, V865A, and I878A impaired both NSP5 hyperphosphorylation and NSP5/VP2 VLS formation. Moreover, NSP5-VP2 interaction does not depend on NSP5 hyperphosphorylation. The NSP5 tail region is required for VP2 interaction. Notably, VP2 L124A expression acts as a dominant-negative element by disrupting the formation of either VLS or viroplasms and blocking RNA synthesis. In silico analyses revealed that VP2 L124, V865, and I878 are conserved among RV species A to H. Detailed knowledge of the protein interaction interface required for viroplasm formation may facilitate the design of broad-spectrum antivirals to block RV replication.IMPORTANCE Alternative treatments to combat rotavirus infection are a requirement for susceptible communities where vaccines cannot be applied. This demand is urgent for newborn infants, immunocompromised patients, adults traveling to high-risk regions, and even for the livestock industry. Aside from structural and physiological divergences among RV species studied before now, all replicate within cytosolic inclusions termed viroplasms. These inclusions are composed of viral and cellular proteins and viral RNA. Viroplasm-like structures (VLS), composed of RV protein NSP5 with either NSP2 or VP2, are models for investigating viroplasms. In this study, we identified a conserved amino acid in the VP2 protein, L124, necessary for its interaction with NSP5 and the formation of both VLSs and viroplasms. As RV vaccines cover a narrow range of viral strains, the identification of VP2 L124 residue lays the foundations for the design of drugs that specifically block NSP5-VP2 interaction as a broad-spectrum RV antiviral.

SUBMITTER: Buttafuoco A

PROVIDER: S-EPMC7081909 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Conserved Rotavirus NSP5 and VP2 Domains Interact and Affect Viroplasm.

Buttafuoco Antonino A Michaelsen Kevin K Tobler Kurt K Ackermann Mathias M Fraefel Cornel C Eichwald Catherine C

Journal of virology 20200317 7

One step of the life cycle common to all rotaviruses (RV) studied so far is the formation of viroplasms, membrane-less cytosolic inclusions providing a microenvironment for early morphogenesis and RNA replication. Viroplasm-like structures (VLS) are simplified viroplasm models consisting of complexes of nonstructural protein 5 (NSP5) with the RV core shell VP2 or NSP2. We identified and characterized the domains required for NSP5-VP2 interaction and VLS formation. VP2 mutations L124A, V865A, and ...[more]

PMID: 31915278

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Project description:Rotavirus (RV) viroplasms are cytosolic inclusions where both virus genome replication and primary steps of virus progeny assembly take place. A stabilized microtubule cytoskeleton and lipid droplets are required for the viroplasm formation, which involves several virus proteins. The viral spike protein VP4 has not previously been shown to have a direct role in viroplasm formation. However, it is involved with virus-cell attachment, endocytic internalization, and virion morphogenesis. Moreover, VP4 interacts with actin cytoskeleton components, mainly in processes involving virus entrance and egress, and thereby may have an indirect role in viroplasm formation. In this study, we used reverse genetics to construct a recombinant RV, rRV/VP4-BAP, that contains a biotin acceptor peptide (BAP) in the K145-G150 loop of the VP4 lectin domain, permitting live monitoring. The recombinant virus was replication competent but showed a reduced fitness. We demonstrate that rRV/VP4-BAP infection, as opposed to rRV/wt infection, did not lead to a reorganized actin cytoskeleton as viroplasms formed were insensitive to drugs that depolymerize actin and inhibit myosin. Moreover, wild-type (wt) VP4, but not VP4-BAP, appeared to associate with actin filaments. Similarly, VP4 in coexpression with NSP5 and NSP2 induced a significant increase in the number of viroplasm-like structures. Interestingly, a small peptide mimicking loop K145-G150 rescued the phenotype of rRV/VP4-BAP by increasing its ability to form viroplasms and hence improve virus progeny formation. Collectively, these results provide a direct link between VP4 and the actin cytoskeleton to catalyze viroplasm assembly. IMPORTANCE The spike protein VP4 participates in diverse steps of the rotavirus (RV) life cycle, including virus-cell attachment, internalization, modulation of endocytosis, virion morphogenesis, and virus egress. Using reverse genetics, we constructed for the first time a recombinant RV, rRV/VP4-BAP, harboring a heterologous peptide in the lectin domain (loop K145-G150) of VP4. The rRV/VP4-BAP was replication competent but with reduced fitness due to a defect in the ability to reorganize the actin cytoskeleton, which affected the efficiency of viroplasm assembly. This defect was rescued by adding a permeable small-peptide mimicking the wild-type VP4 loop K145-G150. In addition to revealing a new role of VP4, our findings suggest that rRV harboring an engineered VP4 could be used as a new dual vaccination platform providing immunity against RV and additional heterologous antigens.

Project description:IntroductionIndividuals with greater affect variability (i.e., moment-to-moment fluctuations possibly reflecting emotional dysregulation) are at risk for greater systemic inflammation, which is associated with cardiovascular disease. Some evidence suggests that affect variability is linked with poorer health indicators only among those with higher average levels of affect, particularly for positive affect (PA), and that associations may be non-linear. The present study sought to examine whether links between both PA and negative affect (NA) variability and inflammation are moderated by average level of affect.MethodsParticipants (N = 300, 50 % female, ages 21-70, 60 % non-Hispanic White, 19 % Hispanic, 15 % non-Hispanic Black) completed a lab assessment and provided a blood sample to measure systemic inflammation (i.e., TNF-α, IL-6, CRP). Affect was collected via a two-day ecological momentary assessment protocol where reports were collected about every 45-min during waking hours. Momentary affect ratings were averaged across both days (i.e., iM), separately for PA and NA, for each participant. Affect variability was calculated as the person-specific SD (i.e., iSD) of affect reports, separately for PA and NA. Linear and quadratic interactions were tested. Models included covariates for sex, race, and body mass index.ResultsThere were significant interactions between NA iM and NA iSD predicting TNF-α (b = 6.54; p < 0.05) and between PA iM and PA iSD predicting IL-6 (b = 0.45; p < 0.05). Specifically, the association between these affect variability indicators and inflammatory markers were suggestive of a positive association among those with higher average affect but a negative association among those with lower average affect. There was no evidence of non-linear associations between affect and inflammation.DiscussionIncorporating interactive effects between affect variability and average affect may be an important consideration in understanding affective-inflammatory associations.

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Conserved Rotavirus NSP5 and VP2 Domains Interact and Affect Viroplasm.

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Conserved Rotavirus NSP5 and VP2 Domains Interact and Affect Viroplasm.

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