Background Variant influenza virus infections are rare but may have pandemic potential if person-to-person transmission is efficient. We describe the epidemiology of a multistate outbreak of an influenza A(H3N2) variant virus (H3N2v) first identified in 2011. Methods We identified laboratory-confirmed cases of H3N2v and used a standard case report form to characterize illness and exposures. We considered illness to result from person-to-person H3N2v transmission if swine contact was not identified within 4 days prior to illness onset. Results From 9 July to 7 September 2012, we identified 306 cases of H3N2v in 10 states. The median age of all patients was 7 years. Commonly reported signs and symptoms included fever (98%), cough (85%), and fatigue (83%). Sixteen patients (5.2%) were hospitalized, and 1 fatal case was identified. The majority of those infected reported agricultural fair attendance (93%) and/or contact with swine (95%) prior to illness. We identified 15 cases of possible person-to-person transmission of H3N2v. Viruses recovered from patients were 93%–100% identical and similar to viruses recovered from previous cases of H3N2v. All H3N2v viruses examined were susceptible to oseltamivir and zanamivir and resistant to adamantane antiviral medications. Conclusions In a large outbreak of variant influenza, the majority of infected persons reported exposures, suggesting that swine contact at an agricultural fair was a risk for H3N2v infection. We identified limited person-to-person H3N2v virus transmission, but found no evidence of efficient or sustained person-to-person transmission. Fair managers and attendees should be aware of the risk of swine-to-human transmission of influenza viruses in these settings.

The infected-cell protein 22 (ICP22), a regulatory protein encoded by the ␣22 gene of herpes simplex virus 1, is required for the optimal expression of a set of late viral proteins that includes the products of the U S 11, U L 38, and U L 41 genes. ICP22 has two activities. Thus, ICP22 and the U L 13 protein kinase mediate the activation of cdc2 and degradation of its partners, cyclins A and B. cdc2 and its new partner, the DNA polymerase accessory factor (U L 42), bind topoisomerase II␣ in an ICP22-dependent manner. In addition, ICP22 and U L 13 mediate an intermediate phosphorylation of the carboxyl terminus of RNA polymerase II (RNA POL II). Here we report another function of ICP22. Thus, ICP22 physically interacts with cdk9, a constitutively active cyclin-dependent kinase involved in transcriptional regulation. A protein complex containing ICP22 and cdk9 phosphorylates in vitro the carboxyl-terminal domain of RNA POL II in a viral U S 3 protein kinase-dependent fashion. Finally, the carboxyl-terminal domain of RNA POL II fused to glutathione S-transferase is phosphorylated in reaction mixtures containing complexes pulled down with ICP22 or cdk9 immune precipitated from lysates of wild-type parent virus or ⌬U L 13 but not ⌬U S 3 mutant-infected cells. The experiments described here place ICP22 and cdk9 in a complex with the carboxyl-terminal domain of RNA POL II. At the same time we confirm the requirement of ICP22 and the U L 13 protein kinase in the posttranslational modification of RNA POL II that alters its electrophoretic mobility, although U S 3 kinase appears to play a role in a cell-type-dependent fashion.Earlier studies from this laboratory have shown that infected-cell protein 22 (ICP22), a product of the ␣22 gene of herpes simplex virus 1 (HSV-1), mediates the activation of cdc2 and the degradation of its partners, cyclins A and B (2, 3). cdc2 acquires a new partner, the viral DNA polymerase-associated factor encoded by the U L 42 open reading frame (4). The complex of cdc2 and U L 42 binds topoisomerase II␣ in an ICP22-dependent manner (5). Finally, ICP22 and the protein kinase encoded by the U L 13 open reading frame are required both for the activation of cdc2 and for the optimal expression of a subset of late viral proteins exemplified by three proteins encoded by the U L 38, U L 41, and U S 11 genes (3,23,27). Independently, Spencer and associates reported that ICP22 and the U L 13 protein kinase mediate a posttranslational modification of the RNA polymerase (POL) II that is reflected in an "intermediate" electrophoretic mobility between that of hyperphosphorylated (RNA POL IIo) and hypophosphorylated (RNA POL IIa) states (12,14,26,29). Both the recruitment of topoisomerase II␣ and the modification of RNA POL II could account for optimization of the synthesis of the subset of late proteins. To resolve the question further, it became desirable to investigate the nature of the interaction between ICP22 and RNA POL II.Cyclin-dependent kinases (cdk's) can be broadly categorized into two subsets, o...

ICP22 is a multifunctional herpes simplex virus 1 (HSV-1) regulatory protein that regulates the accumulation of a subset of late (␥ 2 ) proteins exemplified by U L 38, U L 41, and U S 11. ICP22 binds the cyclin-dependent kinase 9 (cdk9) but not cdk7, and this complex in conjunction with viral protein kinases phosphorylates the carboxyl terminus of RNA polymerase II (Pol II) in vitro. The primary function of cdk9 and its partners, the cyclin T variants, is in the elongation of RNA transcripts, although functions related to the initiation and processing of transcripts have also been reported. We report two series of experiments designed to probe the role of cdk9 in infected cells. In the first, infected cells were treated with 5,6-dichloro-1-␤-D-ribofuranosylbenzimidazole (DRB), a specific inhibitor of cdk9. In cells treated with DRB, the major effect was in the accumulation of viral RNAs and proteins regulated by ICP22. The accumulation of ␣, ␤, or ␥ proteins not regulated by ICP22 was not affected by the drug. The results obtained with DRB were duplicated in cells transfected with small interfering RNA (siRNA) targeting cdk9 mRNAs. Interestingly, DRB and siRNA reduced the levels of ICP22 but not those of other ␣ gene products. In addition, cdk9 and ICP22 appeared to colocalize with RNA Pol II in wild-type-virus-infected cells but not in ⌬U L 13-infected cells. We conclude that cdk9 plays a critical role in the optimization of expression of genes regulated by ICP22 and that one function of cdk9 in HSV-1-infected cells may be to bring ICP22 into the RNA Pol II transcriptional complex.The studies described in this report center on the role of infected cell protein 22 (ICP22), an ␣ (immediate early) protein in viral replication. Mutants lacking ICP22 yield reduced levels of viral progeny in a cell-type-dependent manner (36). The protein appears to perform several functions (24). A key function expressed by the carboxyl-terminal domain (CTD) of ICP22 in conjunction with the viral U L 13 protein kinase is to enhance the synthesis of a subset of late (␥ 2 ) proteins exemplified by the products of the U L 38, U L 41, and U S 11 genes (2,24,31,37). In earlier studies, this laboratory reported that ICP22 and the U L 13 protein kinase mediate the activation of cdc2 and degradation of its partners, cyclins A and B (3, 4). cdc2 and its new partner, the viral DNA polymerase accessory factor (U L 42), bind topoisomerase II␣ in an ICP22-dependent manner (1, 4). In addition, ICP22 and U L 13 mediate an intermediate phosphorylation of the carboxyl terminus of RNA polymerase II (Pol II) in Vero cells (14,18,34,35).Subsequent studies designed to elucidate the interaction of ICP22 with RNA Pol II led to the discovery that ICP22 physically interacts with cyclin-dependent kinase 9 (cdk9) and that the protein complex containing ICP22 and cdk9 phosphorylated the CTD of RNA Pol II in a viral U S 3 protein kinasedependent fashion in vitro (8). These studies also showed that the CTD of RNA Pol II fused to glutathione S-transferase was phos...

Co-circulation of H5N1 in poultry and humans during seasonal influenza epidemic periods signals the need for enhanced surveillance and biosafety measures.