Surveillance for Mosquitoborne Transmission of Zika Virus, New York City, NY, USA, 2016.

A large number of imported cases of Zika virus infection and the potential for transmission by Aedes albopictus mosquitoes prompted the New York City Department of Health and Mental Hygiene to conduct sentinel, enhanced passive, and syndromic surveillance for locally acquired mosquitoborne Zika virus infections in New York City, NY, USA, during June-October 2016. Suspected case-patients were those >5 years of age without a travel history or sexual exposure who had >3 compatible signs/symptoms (arthralgia, fever, conjunctivitis, or rash). We identified 15 suspected cases and tested urine samples for Zika virus by using real-time reverse transcription PCR; all results were negative. We identified 308 emergency department visits for Zika-like illness, 40,073 visits for fever, and 17 unique spatiotemporal clusters of visits for fever. We identified no evidence of local transmission. Our experience offers possible surveillance tools for jurisdictions concerned about local mosquitoborne Zika virus or other arboviral transmission.

Measles infection in persons with secondary vaccine failure, New York City, 2018-19.

A large measles outbreak in New York City, which included cases among vaccinated persons and adults presumed to be immune, provided the opportunity to better understand vaccine failure and the potential impact on measles transmission. Immunoglobulin G (IgG) avidity can distinguish primary (low avidity IgG, indicating no evidence of prior immunity) versus secondary vaccine failure (high avidity IgG, indicating prior immune response and waning antibody). Measles IgG avidity was measured on samples from 62 persons: avidity was high in 53 (16 vaccinated and 37 with unknown vaccination history) and low in 9 (1 recently vaccinated and 8 with unknown vaccination history). Secondary transmission from 2 persons with high-avidity IgG results occurred. These findings illustrate that in settings of sustained measles elimination, measles infection and transmission can occur in persons with secondary vaccine failure, underscoring the need to maintain a high index of suspicion for measles during an outbreak despite prior or presumed prior vaccination.

Anti-alpha-actinin antibodies: a new marker of lupus nephritis.

The exact role of anti-ds (double stranded) DNA antibodies in the pathogenesis of kidney injury in lupus nephritis remains a focus of continuing investigation. One theory explaining the pathogenicity of anti-dsDNA antibodies in lupus nephritis is direct cross-reactivity with renal antigens. Several years ago, alpha-actinin was identified as a major cross-reactive target for pathogenic anti-dsDNA antibodies in murine SLE. Indeed, binding of a nephritogenic murine anti-dsDNA antibody was stronger to the alpha-actinin derived from a lupus prone mouse mesangial cell line as compared to alpha-actinin in a non-autoimmune mouse mesangial cell line. Furthermore, we recently showed that immunization of non-autoimmune mice with alpha-actinin induces anti-chromatin antibodies, glomerular IgG deposition and proteinuria. In humans, anti-alpha-actinin autoantibodies (Ab) were associated with anti-dsDNA Ab in SLE. In those patients, anti-alpha-actinin rather than anti-dsDNA Ab were significantly associated with glomerulonephritis and disease activity. The anti-alpha-actinin reactivity was associated with high avidity anti-dsDNA Ab. Moreover, the anti-alpha-actinin response was related to the actin-binding site of alpha-actinin. Taken together, these studies indicate that detection of anti-alpha-actinin Ab, in association with anti-dsDNA Ab, may constitute a new marker in lupus nephritis.

Alpha-actinin immunization elicits anti-chromatin autoimmunity in nonautoimmune mice.

Anti-dsDNA Abs are characteristic of lupus and can be found deposited in the kidneys of lupus mice. Previously, we have shown that pathogenic anti-dsDNA Abs as well as Ig eluted from the kidneys of nephritic lupus mice cross-react with alpha-actinin. Moreover, cross-reactivity with alpha-actinin characterizes nephritogenic anti-dsDNA Abs in humans with lupus as well. To determine whether Abs generated against alpha-actinin in vivo cross-react with nuclear Ags, we s.c. immunized 10-wk-old female BALB/c mice (and several other nonautoimmune mice strains) with alpha-actinin in adjuvant. Immunized but not control mice displayed high titers of anti-nuclear Abs and IgG anti-chromatin autoantibodies, hypergammaglobulinemia, renal Ig deposition, and proteinuria. The specificity of the anti-chromatin response was determined by Western blotting of purified chromatin with serum from alpha-actinin immunized mice. By proteomic analysis, a 25-kDa doublet band was conclusively identified as high mobility group box (HMGB) proteins 1 and 3, and a 70-kDa band was identified as heat shock protein 70 (hsp70), both of which are known antigenic targets in murine lupus. Binding to purified HMGB1 and hsp70 by immunized mice sera was confirmed by ELISA and Western blot. Immunized mice sera binding to both 25- and 70-kDa bands were significantly inhibited by alpha-actinin and chromatin. Importantly, a panel of nephritogenic mAbs had significantly higher affinity for alpha-actinin, chromatin, HMGB, and hsp70 as compared with nonpathogenic Abs, suggesting a common motif in these Ags that is targeted by pathogenic autoantibodies.

Differential binding of cross-reactive anti-DNA antibodies to mesangial cells: the role of alpha-actinin.

Target Ag display is a necessary requirement for the expression of certain immune-mediated kidney diseases. We previously had shown that anti-DNA Abs that cross-react with alpha-actinin may be important in the pathogenesis of murine and human lupus nephritis; in murine models, we had found that a significant proportion of pathogenic serum and kidney-deposited Igs are alpha-actinin reactive. Furthermore, a pathogenic anti-DNA/alpha-actinin Ab showed enhanced binding to immortalized mesangial cells (MCs) derived from a lupus prone MRL-lpr/lpr mouse as compared with MCs from BALB/c mice which are not susceptible to spontaneous lupus, suggesting that kidney alpha-actinin expression may be contributing to nephritis. In the current study, we established that two isoforms of alpha-actinin that are present in the kidney, alpha-actinin 1 and alpha-actinin 4, can both be targeted by anti-alpha-actinin Abs. We found novel sequence polymorphisms between MRL-lpr/lpr and BALB/c in the gene for alpha-actinin 4. Moreover, alpha-actinin 4 and a splice variant of alpha-actinin 1 were both expressed at significantly higher levels (mRNA and protein) in MCs from the lupus prone MRL-lpr/lpr strain. Significantly, we were able to confirm these differences in intact kidney by examining glomerular Ig deposition of anti-alpha-actinin Abs. We conclude that enhanced alpha-actinin expression may determine the extent of Ig deposition in the Ab-mediated kidney disease in lupus. Modulation of Ag expression may be a promising approach to down-regulate immune complex formation in the target organ in individuals with circulating pathogenic Abs.

BAFF overexpression and accelerated glomerular disease in mice with an incomplete genetic predisposition to systemic lupus erythematosus.

OBJECTIVE: To determine whether overexpression of BAFF can accelerate the development of systemic lupus erythematosus-associated end-organ disease in hosts with an underlying autoimmune diathesis. METHODS: We introduced a BAFF transgene (Tg) into autoimmune-prone B6.Sle1 and B6.Nba2 mice and evaluated these mice for serologic autoimmunity and renal pathology. RESULTS: B6.Sle1.BAFF and B6.Nba2.BAFF mice, but not non-Tg littermates, frequently developed severe glomerular pathology by 3 months of age. Age-matched B6.BAFF mice, despite renal Ig deposits and increases in B cells and Ig production similar to those in B6.Sle1.BAFF and B6.Nba2.BAFF mice, did not develop glomerular pathology. In B6.Sle1.BAFF and B6.Nba2.BAFF mice, severity of glomerular disease did not obligately correlate with circulating levels of IgG anti-chromatin and/or anti-double-stranded DNA antibodies or with amounts of these autoantibodies deposited in the kidneys. Even in mice with severe glomerular disease, renal tubulointerstitial infiltrates were very limited, and increased proteinuria was not detected. CONCLUSION: BAFF-driven effects on glomerular pathology may be mediated, at least in part, by autoantibodies with specificities other than chromatin and/or by autoantibody-independent means. There is an uncoupling of BAFF-driven precocious glomerular pathology from concomitant development of clinically apparent renal disease, strongly suggesting that BAFF overexpression works in concert with other factors to promote overt renal disease.

Alpha-actinin is a cross-reactive renal target for pathogenic anti-DNA antibodies.

Anti-DNA Abs commonly found in patients with systemic lupus erythematosus are thought to play an important pathogenic role in lupus nephritis. Anti-DNA Abs may contribute to renal disease by cross-reactivity with renal Ags, the identity of which remain elusive. To identify a target Ag for pathogenic anti-DNA Abs, we performed Western blotting and immunoprecipitations of mesangial cell lysates from the lupus-prone MRL-lpr/lpr mouse and a nonautoimmune BALB/c mouse with the pathogenic anti-DNA Ab R4A. We found that R4A (but not a nonpathogenic Ab mutant of R4A) binds to and immunoprecipitates a 100-kDa protein expressed on the cell surface and in lysates of MRL-lpr/lpr mesangial cells. DNase treatment of the lysate and of the R4A Ab did not effect binding, indicating that the binding of R4A to the 100-kDa protein was direct and not mediated by an antigenic bridge containing DNA. Binding was greatly diminished in BALB/c lysates, suggesting that Ag expression or availability at the level of the target organ may be a factor in determining susceptibility to lupus nephritis. Following identification of this 100-kDa protein as nonmuscle alpha-actinin, binding of R4A to alpha-actinin was confirmed by Western blot, ELISA, inhibition studies, and immunofluorescence. High titers of anti-alpha-actinin Abs were present in sera and kidney eluates of lupus mice with active nephritis. These results indicate that the nephritogenicity of some anti-DNA Abs may be mediated via cross-reactivity with alpha-actinin. Furthermore, variations in target Ag display between individuals may underlie differential susceptibility to anti-DNA Ab-induced renal disease.

Differential effects of interleukin-4 in peptide induced autoimmunity.

BALB/c mice immunized with multimeric DWEYSVWLSN develop IgG1 anti-DNA antibodies and glomerular immunoglobulin deposits, leading us to investigate the role of IL-4 in this model of antigen induced lupus. Splenocytes from DWEYSVWLSN immunized mice secreted IL-4 but not gamma-interferon. Following peptide immunization, IgG1 anti-peptide and anti-DNA antibodies were significantly higher in IL-4 wild type mice, while IgM and IgG3 anti-DNA levels were significantly higher in IL-4 knockout mice. Titers of IgG anti-laminin and anti-histone, but not anti-Sm/RNP and anti-cardiolipin antibodies, were significantly higher in the IL-4 wild type group. Glomerular immunoglobulin deposition was substantially decreased in IL-4 knockout mice. We conclude that while IL-4 does not materially affect the generation of some autoantibody responses associated with peptide induced autoimmunity, IL-4 deficiency inhibits kidney immunoglobulin deposition. The effect of IL-4 on humoral autoimmunity in lupus is complex, and is dependent on genetic background, the antigenic trigger and stage of disease.

A peptide DNA surrogate accelerates autoimmune manifestations and nephritis in lupus-prone mice.

Lupus-associated anti-DNA Abs display features of Ag selection, yet the triggering Ag in the disease is unknown. We previously demonstrated that the peptide DWEYSVWLSN is bound by a pathogenic anti-DNA Ab, and that immunization of nonautoimmune mice with this peptide induces autoantibodies and renal Ig deposition. To elucidate differences in the induced B cell responses in mice genetically predisposed to autoimmunity, young (NZB x NZW)F(1) mice were immunized with this peptide DNA mimetope. DWEYSVWLSN-immunized mice had significantly increased IgG anti-dsDNA, anti-laminin, and anti-cardiolipin Ab titers compared with controls. In addition, glomerular histopathology in the form of endocapillary disease and crescent formation was markedly more severe in DWEYSVWLSN-immunized mice. Analysis of mAbs from DWEYSVWLSN-immunized mice revealed that anti-peptide Abs were often cross-reactive with DNA. Genetic elements used in the Ab response in immunized mice were homologous to those used in the spontaneous anti-DNA response in (NZB x NZW)F(1) mice, as well as in other, experimentally induced anti-DNA Abs. Our results indicate that peptide immunization can induce a molecular genetic response common to a variety of stimuli that break tolerance to mammalian dsDNA. Based on the similarity between spontaneously arising anti-DNA Abs and several types of induced anti-DNA Abs, we suggest that there may be more than a single Ag that can trigger systemic lupus erythematosus.