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Evidence of cross-reactive immunity to 2009 pandemic influenza A virus in workers seropositive to swine H1N1 influenza viruses circulating in Italy.

De Marco MA, Porru S, Cordioli P, Cesana BM, Moreno A, Calzoletti L, Bonfanti L, Boni A, Di Carlo AS, Arici C, Carta A, Castrucci MR, Donatelli I, Tomao P, Peri VM, Di Trani L, Vonesch N - PLoS ONE (2013)

Bottom Line: In both pre-pandemic and post-pandemic peak subperiods, SWs showed significantly higher swH1N1 seroprevalences when compared with Cs (52.4% vs. 4.7% and 59% vs. 9.7%, respectively).Comparable HI results were obtained against H1N1pdm antigen (58.3% vs. 7.7% and 59% vs. 31.7%, respectively).A significant increase of H1N1pdm seroprevalences occurred in the post-pandemic peak subperiod in the Cs (p<0.001) whereas SWs showed no differences between the two subperiods, suggesting a possible occurrence of cross-protective immunity related to previous swH1N1 infections.

View Article: PubMed Central - PubMed

Affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Rome, Italy. mariaalessandra.demarco@iss.it

ABSTRACT

Background: Pigs play a key epidemiologic role in the ecology of influenza A viruses (IAVs) emerging from animal hosts and transmitted to humans. Between 2008 and 2010, we investigated the health risk of occupational exposure to swine influenza viruses (SIVs) in Italy, during the emergence and spread of the 2009 H1N1 pandemic (H1N1pdm) virus.

Methodology/principal findings: Serum samples from 123 swine workers (SWs) and 379 control subjects (Cs), not exposed to pig herds, were tested by haemagglutination inhibition (HI) assay against selected SIVs belonging to H1N1 (swH1N1), H1N2 (swH1N2) and H3N2 (swH3N2) subtypes circulating in the study area. Potential cross-reactivity between swine and human IAVs was evaluated by testing sera against recent, pandemic and seasonal, human influenza viruses (H1N1 and H3N2 antigenic subtypes). Samples tested against swH1N1 and H1N1pdm viruses were categorized into sera collected before (n. 84 SWs; n. 234 Cs) and after (n. 39 SWs; n. 145 Cs) the pandemic peak. HI-antibody titers ≥10 were considered positive. In both pre-pandemic and post-pandemic peak subperiods, SWs showed significantly higher swH1N1 seroprevalences when compared with Cs (52.4% vs. 4.7% and 59% vs. 9.7%, respectively). Comparable HI results were obtained against H1N1pdm antigen (58.3% vs. 7.7% and 59% vs. 31.7%, respectively). No differences were found between HI seroreactivity detected in SWs and Cs against swH1N2 (33.3% vs. 40.4%) and swH3N2 (51.2 vs. 55.4%) viruses. These findings indicate the occurrence of swH1N1 transmission from pigs to Italian SWs.

Conclusion/significance: A significant increase of H1N1pdm seroprevalences occurred in the post-pandemic peak subperiod in the Cs (p<0.001) whereas SWs showed no differences between the two subperiods, suggesting a possible occurrence of cross-protective immunity related to previous swH1N1 infections. These data underline the importance of risk assessment and occupational health surveillance activities aimed at early detection and control of SIVs with pandemic potential in humans.

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HI antibody reactivity against swH1N1 and H1N1pdm viruses in SWs (Italy, 2008–2010).Serum samples were collected from swine workers (SWs) in the pre-pandemic peak (15 December 2008–1 November 2009) and post-pandemic peak (2 November 2009–3 October 2010) periods and tested by haemagglutination inhibition (HI) assay. Individual HI results referred to the three cutoff levels (≥10, ≥20 and ≥40) chosen for the statistical analysis of data, and ranging from 10 (minimum level of detection) to 40 (protective antibody titer). No significant difference in seroprevalence rate (SPR) was found in SWs sera tested by HI assay against swH1N1 (Figure 1A) and H1N1pdm (Figure 1B) viruses (viruses details and SPRs are shown in Table 5).
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pone-0057576-g001: HI antibody reactivity against swH1N1 and H1N1pdm viruses in SWs (Italy, 2008–2010).Serum samples were collected from swine workers (SWs) in the pre-pandemic peak (15 December 2008–1 November 2009) and post-pandemic peak (2 November 2009–3 October 2010) periods and tested by haemagglutination inhibition (HI) assay. Individual HI results referred to the three cutoff levels (≥10, ≥20 and ≥40) chosen for the statistical analysis of data, and ranging from 10 (minimum level of detection) to 40 (protective antibody titer). No significant difference in seroprevalence rate (SPR) was found in SWs sera tested by HI assay against swH1N1 (Figure 1A) and H1N1pdm (Figure 1B) viruses (viruses details and SPRs are shown in Table 5).

Mentions: Taking into account the conventional 1 November 2009 cutoff date (pre- and post- pandemic peak), seroprevalences to swH1N1 and H1N1pdm viruses were compared, as shown in Table 5, Figures 1 and Figure 2. Binary logistic regression showed higher SPRs in SWs in both pre- and post-pandemic period (Table 5), at all cutoff levels with the exception of cutoff ≥40 for swH1N1 in the post-pandemic period, where very low cell frequency was observed.


Evidence of cross-reactive immunity to 2009 pandemic influenza A virus in workers seropositive to swine H1N1 influenza viruses circulating in Italy.

De Marco MA, Porru S, Cordioli P, Cesana BM, Moreno A, Calzoletti L, Bonfanti L, Boni A, Di Carlo AS, Arici C, Carta A, Castrucci MR, Donatelli I, Tomao P, Peri VM, Di Trani L, Vonesch N - PLoS ONE (2013)

HI antibody reactivity against swH1N1 and H1N1pdm viruses in SWs (Italy, 2008–2010).Serum samples were collected from swine workers (SWs) in the pre-pandemic peak (15 December 2008–1 November 2009) and post-pandemic peak (2 November 2009–3 October 2010) periods and tested by haemagglutination inhibition (HI) assay. Individual HI results referred to the three cutoff levels (≥10, ≥20 and ≥40) chosen for the statistical analysis of data, and ranging from 10 (minimum level of detection) to 40 (protective antibody titer). No significant difference in seroprevalence rate (SPR) was found in SWs sera tested by HI assay against swH1N1 (Figure 1A) and H1N1pdm (Figure 1B) viruses (viruses details and SPRs are shown in Table 5).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585202&req=5

pone-0057576-g001: HI antibody reactivity against swH1N1 and H1N1pdm viruses in SWs (Italy, 2008–2010).Serum samples were collected from swine workers (SWs) in the pre-pandemic peak (15 December 2008–1 November 2009) and post-pandemic peak (2 November 2009–3 October 2010) periods and tested by haemagglutination inhibition (HI) assay. Individual HI results referred to the three cutoff levels (≥10, ≥20 and ≥40) chosen for the statistical analysis of data, and ranging from 10 (minimum level of detection) to 40 (protective antibody titer). No significant difference in seroprevalence rate (SPR) was found in SWs sera tested by HI assay against swH1N1 (Figure 1A) and H1N1pdm (Figure 1B) viruses (viruses details and SPRs are shown in Table 5).
Mentions: Taking into account the conventional 1 November 2009 cutoff date (pre- and post- pandemic peak), seroprevalences to swH1N1 and H1N1pdm viruses were compared, as shown in Table 5, Figures 1 and Figure 2. Binary logistic regression showed higher SPRs in SWs in both pre- and post-pandemic period (Table 5), at all cutoff levels with the exception of cutoff ≥40 for swH1N1 in the post-pandemic period, where very low cell frequency was observed.

Bottom Line: In both pre-pandemic and post-pandemic peak subperiods, SWs showed significantly higher swH1N1 seroprevalences when compared with Cs (52.4% vs. 4.7% and 59% vs. 9.7%, respectively).Comparable HI results were obtained against H1N1pdm antigen (58.3% vs. 7.7% and 59% vs. 31.7%, respectively).A significant increase of H1N1pdm seroprevalences occurred in the post-pandemic peak subperiod in the Cs (p<0.001) whereas SWs showed no differences between the two subperiods, suggesting a possible occurrence of cross-protective immunity related to previous swH1N1 infections.

View Article: PubMed Central - PubMed

Affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Rome, Italy. mariaalessandra.demarco@iss.it

ABSTRACT

Background: Pigs play a key epidemiologic role in the ecology of influenza A viruses (IAVs) emerging from animal hosts and transmitted to humans. Between 2008 and 2010, we investigated the health risk of occupational exposure to swine influenza viruses (SIVs) in Italy, during the emergence and spread of the 2009 H1N1 pandemic (H1N1pdm) virus.

Methodology/principal findings: Serum samples from 123 swine workers (SWs) and 379 control subjects (Cs), not exposed to pig herds, were tested by haemagglutination inhibition (HI) assay against selected SIVs belonging to H1N1 (swH1N1), H1N2 (swH1N2) and H3N2 (swH3N2) subtypes circulating in the study area. Potential cross-reactivity between swine and human IAVs was evaluated by testing sera against recent, pandemic and seasonal, human influenza viruses (H1N1 and H3N2 antigenic subtypes). Samples tested against swH1N1 and H1N1pdm viruses were categorized into sera collected before (n. 84 SWs; n. 234 Cs) and after (n. 39 SWs; n. 145 Cs) the pandemic peak. HI-antibody titers ≥10 were considered positive. In both pre-pandemic and post-pandemic peak subperiods, SWs showed significantly higher swH1N1 seroprevalences when compared with Cs (52.4% vs. 4.7% and 59% vs. 9.7%, respectively). Comparable HI results were obtained against H1N1pdm antigen (58.3% vs. 7.7% and 59% vs. 31.7%, respectively). No differences were found between HI seroreactivity detected in SWs and Cs against swH1N2 (33.3% vs. 40.4%) and swH3N2 (51.2 vs. 55.4%) viruses. These findings indicate the occurrence of swH1N1 transmission from pigs to Italian SWs.

Conclusion/significance: A significant increase of H1N1pdm seroprevalences occurred in the post-pandemic peak subperiod in the Cs (p<0.001) whereas SWs showed no differences between the two subperiods, suggesting a possible occurrence of cross-protective immunity related to previous swH1N1 infections. These data underline the importance of risk assessment and occupational health surveillance activities aimed at early detection and control of SIVs with pandemic potential in humans.

Show MeSH
Related in: MedlinePlus