Division of Virology, Department of Microbiology and Immunology, Tottori University Faculty of Medicine, Yonago City, Japan.
J Med Virol. 2013 Nov;85(11):1871-7. doi: 10.1002/jmv.23700.
A novel swine-origin influenza A(H1N1)pdm09 virus has been circulating in humans since March-April, 2009. The 2009-2010 epidemic involved predominantly a single subtype of A(H1N1)pdm09 (at 96%, 46/48) in the sentinel sites of this study. However, A(H1N1)pdm09 started to circulate together with other type/subtype (49%, 33/68) at the first peak in the next epidemic season in 2010-2011: A(H1N1)pdm09/A(H3N2) (9%, 6/68), A(H1N1)pdm09/B (35%, 24/68), and A(H1N1)pdm09/A(H3N2)/B (4%, 3/68). Single infection of A(H1N1)pdm09 became a rare event (8%, 5/65) at the second peak of the same season in 2010-2011 compared with that at the first peak (50%, 34/68). Concurrently with this decline, single infections of others, A(H3N2) or B, became evident (6%, 4/65; 14%, 9/65, respectively). Triple infections were more common (29%, 19/65) at the second peak than at the first peak (4%). The A(H1N1)pdm09 detected in 2010-2011 produced less virus upon 72 hr of incubation in vitro after the inoculations at 10(4) and 3,300 copies/ml (2.3 × 10(9) and 2.3 × 10(9) copies/ml on average) than that in 2009-2010 (3.7 × 10(9) and 1.3 × 10(10) copies/ml on average; P<0.05 by ANOVA test), respectively. As described above, the replication capacity of A(H1N1)pdm09 seems to have deteriorated in the 2010-2011 season presumably due to substantial herd immunity and allowed the existence of other type/subtype. These results suggest that assessment of replication capacity is indispensable for analysis of influenza epidemics.
一种新型的猪源流感 A(H1N1)pdm09 病毒自 2009 年 3 月至 4 月以来一直在人类中传播。本研究哨点监测显示，2009-2010 年的流行主要涉及单一亚型 A(H1N1)pdm09（96%，46/48）。然而，A(H1N1)pdm09 于 2010-2011 年下一个流行季的首个高峰时开始与其他型/亚型（49%，33/68）共同传播：A(H1N1)pdm09/A(H3N2)（9%，6/68）、A(H1N1)pdm09/B（35%，24/68）和 A(H1N1)pdm09/A(H3N2)/B（4%，3/68）。与上一个流行季的首个高峰（50%，34/68）相比，2010-2011 年的同一流行季的第二个高峰时，A(H1N1)pdm09 的单一感染已成为罕见事件（8%，5/65）。与此同时，其他型/亚型（A(H3N2)或 B）的单一感染变得明显（分别为 6%，4/65；14%，9/65）。与 4%相比，双感染在第二个高峰时更为常见（29%，19/65）。在 2010-2011 年检测到的 A(H1N1)pdm09 在接种 10(4)和 3300 拷贝/ml（平均 2.3×10(9)和 2.3×10(9)拷贝/ml）72 小时后在体外培养中产生的病毒量低于 2009-2010 年（平均 3.7×10(9)和 1.3×10(10)拷贝/ml；ANOVA 检验，P<0.05）。如前所述，A(H1N1)pdm09 的复制能力在 2010-2011 年可能由于大量的群体免疫而下降，从而允许其他型/亚型的存在。这些结果表明，对复制能力的评估对于流感疫情分析是不可或缺的。
