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The emergence of Omicron lineages and descendent subvariants continues to present a severe threat to the effectiveness of vaccines and therapeutic antibodies. We have previ- ously suggested that an insufficient mucosal immunoglobulin A (IgA) response induced by the mRNA vaccines is associated with a surge in breakthrough infections. Here, we further show that the intramuscular mRNA and/or inactivated vaccines cannot suffi- ciently boost the mucosal secretory IgA response in uninfected individuals, particu- larly against the Omicron variant. We thus engineered and characterized recombinant monomeric, dimeric, and secretory IgAl antibodies derived from four neutralizing IgG monoclonal antibodies (mAbs 01A05, rmAb23, DXP-604, and XG014) targeting the receptor-binding domain of the spike protein. Compared to their parental IgG antibod- ies, dimeric and secretory IgAl antibodies showed a higher neutralizing activity against different variants of concern (VOCs), in part due to an increased avidity. Importantly, the dimeric or secretory IgAl form of the DXP-604 antibody significantly outperformed its parental IgG antibody, and neutralized the Omicron lineages BA.1, BA.2, and BA.4/5 with a 25- to 75-fold increase in potency. In human angiotensin converting enzyme 2 (ACE2) transgenic mice, a single intranasal dose of the dimeric IgA DXP-604 conferred prophylactic and therapeutic protection against Omicron BA.5. Thus, dimeric or secre- tory IgA delivered by nasal administration may potentially be exploited for the treatment Iand prevention of Omicron infection, thereby providing an alternative tool for combating immune evasion by the current circulating subvariants and, potentially, future VOCs.

The emergence of pandemic GII.4 norovirus (NoV) strains has been proposed to occur due to changes in receptor usage and thereby to lead to immune evasion. To address this hypothesis, we measured the ability of human sera collected between 1979 and 2010 to block glycan binding of four pandemic GII. 4 noroviruses isolated in the last 4 decades. In total, 268 sera were investigated for 50% blocking titer (BT50) values of virus-like particles (VLPs) against pig gastric mucin (PGM) using 4 VLPs that represent different GII. 4 norovirus variants identified between 1987 and 2012. Pre- and postpandemic sera (sera collected before and after isolation of the reference NoV strain) efficiently prevented binding of VLP strains MD145 (1987), Grimsby (1995), and Houston (2002), but not the Sydney (2012) strain, to PGM. No statistically significant difference in virus-blocking titers was observed between pre- and postpandemic sera. Moreover, paired sera showed that blocking titers of amp;gt;= 160 were maintained over a 6-year period against MD145, Grimsby, and Houston VLPs. Significantly higher serum blocking titers (geometric mean titer [GMT], 1,704) were found among IgA-deficient individuals than among healthy blood donors (GMT, 90.9) (P amp;lt; 0.0001). The observation that prepandemic sera possess robust blocking capacity for viruses identified decades later suggests a common attachment factor, at least until 2002. Our results indicate that serum IgG possesses antibody-blocking capacity and that blocking titers can be maintained for at least 6 years against 3 decades of pandemic GII. 4 NoV. IMPORTANCE Human noroviruses (NoVs) are the major cause of acute gastroenteritis worldwide. Histo-blood group antigens (HBGAs) in saliva and gut recognize NoV and are the proposed ligands that facilitate infection. Polymorphisms in HBGA genes, and in particular a nonsense mutation in FUT2 (G428A), result in resistance to global dominating GII. 4 NoV. The emergence of new pandemic GII. 4 stra, Funding Agencies|Swedish Research Council [320301, 8266]; Swedish Foundation for Strategic Research

The emergence of pandemic GII.4 norovirus (NoV) strains has been proposed to occur due to changes in receptor usage and thereby to lead to immune evasion. To address this hypothesis, we measured the ability of human sera collected between 1979 and 2010 to block glycan binding of four pandemic GII. 4 noroviruses isolated in the last 4 decades. In total, 268 sera were investigated for 50% blocking titer (BT50) values of virus-like particles (VLPs) against pig gastric mucin (PGM) using 4 VLPs that represent different GII. 4 norovirus variants identified between 1987 and 2012. Pre- and postpandemic sera (sera collected before and after isolation of the reference NoV strain) efficiently prevented binding of VLP strains MD145 (1987), Grimsby (1995), and Houston (2002), but not the Sydney (2012) strain, to PGM. No statistically significant difference in virus-blocking titers was observed between pre- and postpandemic sera. Moreover, paired sera showed that blocking titers of amp;gt;= 160 were maintained over a 6-year period against MD145, Grimsby, and Houston VLPs. Significantly higher serum blocking titers (geometric mean titer [GMT], 1,704) were found among IgA-deficient individuals than among healthy blood donors (GMT, 90.9) (P amp;lt; 0.0001). The observation that prepandemic sera possess robust blocking capacity for viruses identified decades later suggests a common attachment factor, at least until 2002. Our results indicate that serum IgG possesses antibody-blocking capacity and that blocking titers can be maintained for at least 6 years against 3 decades of pandemic GII. 4 NoV. IMPORTANCE Human noroviruses (NoVs) are the major cause of acute gastroenteritis worldwide. Histo-blood group antigens (HBGAs) in saliva and gut recognize NoV and are the proposed ligands that facilitate infection. Polymorphisms in HBGA genes, and in particular a nonsense mutation in FUT2 (G428A), result in resistance to global dominating GII. 4 NoV. The emergence of new pandemic GII. 4 stra, Funding Agencies|Swedish Research Council [320301, 8266]; Swedish Foundation for Strategic Research

The emergence of pandemic GII.4 norovirus (NoV) strains has been proposed to occur due to changes in receptor usage and thereby to lead to immune evasion. To address this hypothesis, we measured the ability of human sera collected between 1979 and 2010 to block glycan binding of four pandemic GII. 4 noroviruses isolated in the last 4 decades. In total, 268 sera were investigated for 50% blocking titer (BT50) values of virus-like particles (VLPs) against pig gastric mucin (PGM) using 4 VLPs that represent different GII. 4 norovirus variants identified between 1987 and 2012. Pre- and postpandemic sera (sera collected before and after isolation of the reference NoV strain) efficiently prevented binding of VLP strains MD145 (1987), Grimsby (1995), and Houston (2002), but not the Sydney (2012) strain, to PGM. No statistically significant difference in virus-blocking titers was observed between pre- and postpandemic sera. Moreover, paired sera showed that blocking titers of amp;gt;= 160 were maintained over a 6-year period against MD145, Grimsby, and Houston VLPs. Significantly higher serum blocking titers (geometric mean titer [GMT], 1,704) were found among IgA-deficient individuals than among healthy blood donors (GMT, 90.9) (P amp;lt; 0.0001). The observation that prepandemic sera possess robust blocking capacity for viruses identified decades later suggests a common attachment factor, at least until 2002. Our results indicate that serum IgG possesses antibody-blocking capacity and that blocking titers can be maintained for at least 6 years against 3 decades of pandemic GII. 4 NoV. IMPORTANCE Human noroviruses (NoVs) are the major cause of acute gastroenteritis worldwide. Histo-blood group antigens (HBGAs) in saliva and gut recognize NoV and are the proposed ligands that facilitate infection. Polymorphisms in HBGA genes, and in particular a nonsense mutation in FUT2 (G428A), result in resistance to global dominating GII. 4 NoV. The emergence of new pandemic GII. 4 stra, Funding Agencies|Swedish Research Council [320301, 8266]; Swedish Foundation for Strategic Research

Lactobacillus rhamnosus DSM 14870 and Lactobacillus gasseri DSM 14869 were previously isolated from the vaginal epithelial cells (VEC) of healthy women and selected for the development of the vaginal EcoVag (R) probiotic capsules. EcoVag (R) was subsequently shown to provide long-term cure and reduce relapse of bacterial vaginosis (BV) as an adjunct to antibiotic therapy. To identify genes potentially involved in probiotic activity, we performed genome sequencing and characterization of the two strains. The complete genome analysis of both strains revealed the presence of genes encoding functions related to adhesion, exopolysaccharide (EPS) biosynthesis, antimicrobial activity, and CRISPR adaptive immunity but absence of antibiotic resistance genes. Interesting features of L. rhamnosus DSM 14870 genome include the presence of the spaCBA-srtC gene encoding spaCBA pill and interruption of the gene cluster encoding long galactose-rich EPS by integrases. Unique to L. gasseri DSM 14869 genome was the presence of a gene encoding a putative (1456 amino acid) new adhesin containing two rib/alpha-like repeats. L. rhamnosus DSM 14870 and L. gasseri DSM 14869 showed acidification of the culture medium (to pH 3.8) and a strong adhesion capability to the Caco-2 cell line and VEC. L gasseri DSM 14869 could produce a thick (40 nor) EPS layer and hydrogen peroxide. L. rhamnosus DSM 14870 was shown to produce SpaCBA pili and a 20 nor EPS layer, and could inhibit the growth of Gardnerella vaginalis, a bacterium commonly associated with BV. The genome sequences provide a basis for further elucidation of the molecular basis for their probiotic functions., Funding Agencies|Swedish Research Council (Vetenskapsradet) in Sweden; company Bifodan A/S, Denmark

The emergence of pandemic GII.4 norovirus (NoV) strains has been proposed to occur due to changes in receptor usage and thereby to lead to immune evasion. To address this hypothesis, we measured the ability of human sera collected between 1979 and 2010 to block glycan binding of four pandemic GII. 4 noroviruses isolated in the last 4 decades. In total, 268 sera were investigated for 50% blocking titer (BT50) values of virus-like particles (VLPs) against pig gastric mucin (PGM) using 4 VLPs that represent different GII. 4 norovirus variants identified between 1987 and 2012. Pre- and postpandemic sera (sera collected before and after isolation of the reference NoV strain) efficiently prevented binding of VLP strains MD145 (1987), Grimsby (1995), and Houston (2002), but not the Sydney (2012) strain, to PGM. No statistically significant difference in virus-blocking titers was observed between pre- and postpandemic sera. Moreover, paired sera showed that blocking titers of amp;gt;= 160 were maintained over a 6-year period against MD145, Grimsby, and Houston VLPs. Significantly higher serum blocking titers (geometric mean titer [GMT], 1,704) were found among IgA-deficient individuals than among healthy blood donors (GMT, 90.9) (P amp;lt; 0.0001). The observation that prepandemic sera possess robust blocking capacity for viruses identified decades later suggests a common attachment factor, at least until 2002. Our results indicate that serum IgG possesses antibody-blocking capacity and that blocking titers can be maintained for at least 6 years against 3 decades of pandemic GII. 4 NoV. IMPORTANCE Human noroviruses (NoVs) are the major cause of acute gastroenteritis worldwide. Histo-blood group antigens (HBGAs) in saliva and gut recognize NoV and are the proposed ligands that facilitate infection. Polymorphisms in HBGA genes, and in particular a nonsense mutation in FUT2 (G428A), result in resistance to global dominating GII. 4 NoV. The emergence of new pandemic GII. 4 stra, Funding Agencies|Swedish Research Council [320301, 8266]; Swedish Foundation for Strategic Research

The emergence of pandemic GII.4 norovirus (NoV) strains has been proposed to occur due to changes in receptor usage and thereby to lead to immune evasion. To address this hypothesis, we measured the ability of human sera collected between 1979 and 2010 to block glycan binding of four pandemic GII. 4 noroviruses isolated in the last 4 decades. In total, 268 sera were investigated for 50% blocking titer (BT50) values of virus-like particles (VLPs) against pig gastric mucin (PGM) using 4 VLPs that represent different GII. 4 norovirus variants identified between 1987 and 2012. Pre- and postpandemic sera (sera collected before and after isolation of the reference NoV strain) efficiently prevented binding of VLP strains MD145 (1987), Grimsby (1995), and Houston (2002), but not the Sydney (2012) strain, to PGM. No statistically significant difference in virus-blocking titers was observed between pre- and postpandemic sera. Moreover, paired sera showed that blocking titers of amp;gt;= 160 were maintained over a 6-year period against MD145, Grimsby, and Houston VLPs. Significantly higher serum blocking titers (geometric mean titer [GMT], 1,704) were found among IgA-deficient individuals than among healthy blood donors (GMT, 90.9) (P amp;lt; 0.0001). The observation that prepandemic sera possess robust blocking capacity for viruses identified decades later suggests a common attachment factor, at least until 2002. Our results indicate that serum IgG possesses antibody-blocking capacity and that blocking titers can be maintained for at least 6 years against 3 decades of pandemic GII. 4 NoV. IMPORTANCE Human noroviruses (NoVs) are the major cause of acute gastroenteritis worldwide. Histo-blood group antigens (HBGAs) in saliva and gut recognize NoV and are the proposed ligands that facilitate infection. Polymorphisms in HBGA genes, and in particular a nonsense mutation in FUT2 (G428A), result in resistance to global dominating GII. 4 NoV. The emergence of new pandemic GII. 4 stra, Funding Agencies|Swedish Research Council [320301, 8266]; Swedish Foundation for Strategic Research

The histo-blood group antigens (HBGAs) have recently been suggested to serve as attachment factors for rotavirus VP8* (P-genotype) in vitro and associated with susceptibility in vivo. We thus investigated whether rotavirus antibody titers and genotype specific neutralization titers correlate with HBGA status in Swedish individuals. We investigated the effect of inactivating mutations in the secretor FUT2 (rs601338) and Lewis FUT3 genes (rs28362459, rs3894326, rs812936 and rs778986) on serum IgG antibody titers and neutralizing antibody titers to rotavirus strains of the P[8] and P[6] genotypes in Swedish healthy blood donors and patients with IgA deficiency using genotyping, enzyme linked immunosorbent assay and a neutralization assay. Rotavirus-specific serum IgG and neutralizing antibody titers to the Wa strain (G1P[8]), but not to the ST3 (G4P[6]) strain, were significantly higher in secretors (with at least one functional FUT2 gene) than in non-secretors (P<0.001) (with homozygous nonsense mutation in the FUT2 gene). Thus, our results represent that secretors show elevated rotavirus specific serum antibodies, suggesting a higher susceptibility to rotavirus infections, as compared to non-secretors in Sweden. (C) 2015 Elsevier B.V. All rights reserved., Funding Agencies|Swedish Research Council [K2012-56X-05975-32-3]

Immunoglobulin A deficiency (IgAD) is the most common primary immunodeficiency in the general population. It is defined as a serum IgA level below or equal to 0.07 g/l with normal IgM and IgG levels in children over the age of 4. However, a few cases of reversal of IgAD at later ages have been observed previously, especially in pediatric patients. This study aimed at investigating the frequency of reversal in a large cohort of children and young adults in order to evaluate the present definition of IgAD. Clinical laboratory records from 654 pediatric IgA deficient patients, 4-13 years of age, were retrieved from five university hospitals in Sweden. Follow up in the children where IgA serum levels had been routinely measured was subsequently performed. In addition, follow up of the IgA-levels was also performed at 4, 8 and 16 years of age in children who were IgA deficient at the age of 4 years in a Swedish population-based birth cohort study in Stockholm (BAMSE). Nine out of 39 (23.1 %) children who were identified as IgAD at 4 years of age subsequently increased their serum IgA level above 0.07 g/L. The average age of reversal was 9.53 +/- 2.91 years. In addition, 30 out of the 131 (22.9 %) children with serum IgAD when sampled between 5 and 9.99 years of age reversed their serum IgA level with time. The BAMSE follow up study showed a reversal of IgAD noted at 4 years of age in 8 out of 14 IgAD children at 16 years of age (5 at 8 years of age) where 4 were normalized their serum IgA levels while 4 still showed low serum levels of IgA, yet above the level defining IgAD. The results indicate that using 4 years of age, as a cut off for a diagnosis of IgAD may not be appropriate. Our findings suggest that a diagnosis of IgAD should not be made before the early teens using 0.07 g/L of IgA in serum as a cut off.