Environmental Surveillance of Human Enteroviruses in Shandong Province,China, 2008 to 2012: Serotypes,Temporal Fluctuation,and Molecular Epidemiology

Environmental surveillance is an effective approach in investigating the circulation of polioviruses (PVs) and other human enteroviruses (EVs) in the population. The present report describes the results of environmental surveillance conducted in Shandong Province, China, from 2008 to 2012. A total of 129 sewage samples were collected, and 168 PVs and 1,007 nonpolio enteroviruses (NPEVs) were isolated. VP1 sequencing and typing were performed on all isolates. All PV strains were Sabin-like, with the numbers of VP1 substitutions ranging from 0 to 7. The NPEVs belonged to 19 serotypes, and echovirus 6 (E6), E11, coxsackievirus B3 (CVB3), E3, E12, and E7 were the six main serotypes, which accounted for 18.3%, 14.8%, 14.5%, 12.9%, 9.0%, and 5.7% of NPEVs isolated, respectively. Typical summer-fall peaks of NPEV were observed in the monthly distribution of isolation, and an epidemic pattern of annual circulation was revealed for the common serotypes. Phylogenetic analysis was performed on environmental CVB3 and E3 strains with global reference strains and local strains from aseptic meningitis patients. Shandong strains formed distinct clusters, and a close relationship was observed between local environmental and clinical strains. As an EV-specific case surveillance system is absent in China and many other countries, continuous environmental surveillance should be encouraged to investigate the temporal circulation and phylogeny of EVs in the population.     

Elucidation of Echovirus 30's Origin and Transmission during the 2012 Aseptic Meningitis Outbreak in Guangdong,China, through Continuing Environmental Surveillance

An aseptic meningitis outbreak occurred in Luoding City of Guangdong, China, in 2012, and echovirus type 30 (ECHO30) was identified as the major causative pathogen. Environmental surveillance indicated that ECHO30 was detected in the sewage of a neighboring city, Guangzhou, from 2010 to 2012 and also in Luoding City sewage samples (6/43, 14%) collected after the outbreak. In order to track the potential origin of the outbreak viral strains, we sequenced the VP1 genes of 29 viral strains from clinical patients and environmental samples. Sequence alignments and phylogenetic analyses based on VP1 gene sequences revealed that virus strains isolated from the sewage of Guangzhou and Luoding cities matched well the clinical strains from the outbreak, with high nucleotide sequence similarity (98.5% to 100%) and similar cluster distribution. Five ECHO30 clinical strains were clustered with the Guangdong environmental strains but diverged from strains from other regions, suggesting that this subcluster of viruses most likely originated from the circulating virus in Guangdong rather than having been more recently imported from other regions. These findings underscore the importance of long-term, continuous environmental surveillance and genetic analysis to monitor circulating enteroviruses.     

Prevalence of Multiple Enteroviruses Associated with Hand,Foot, and Mouth Disease in Shijiazhuang City,Hebei Province,China: Outbreaks of Coxsackieviruses A10 and B3

Hand, foot, and mouth disease (HFMD) has been one of the most common infectious diseases in Shijiazhuang City, as is the situation in China overall. In the National HFMD surveillance system, the pathogen detection was focused on EV-A71 and CVA16, and therefore, information on the other EVs is very limited. In order to identify the circulating EV serotypes in the HFMD outbreaks in Shijiazhuang City during 2010–2012, 4045 patients presented with HFMD were recruited in the study, and clinical samples were investigated. Typing of EV serotypes was performed using the molecular typing methods, and phylogenetic analyses based on entire VP1 sequences of human enterovirus 71 (EV-A71), coxsackievirus A16 (CVA16), CVA10 and CVB3 was performed. The results revealed that EV-A71 and CVA16 were the 2 most important pathogens but the circulating trends of the 2 viruses showed a shift, the spread of EV-A71 became increasingly weak, whereas the spread of CVA16 became increasingly stronger. CVA10 and CVB3 were the third and fourth most prevalent pathogens, respectively. Co-infection of two viruses at the same time was not found in these samples. Based on entire VP1 region sequences, the phylogenetic analysis revealed that C4a subgenotype EV-A71, B1a and B1b subgenotype CVA16 continued to evolve. The CVA10 strains were assigned to 4 genotypes (A–D), whereas the CVB3 strains were assigned to 5 genotypes (A–E), with clear geographical and temporal-specific distributions. The Shijiazhuang CVA10 sequences belonged to 4 epidemic lineages within genotype C, whereas the Shijiazhuang CVB3 sequences belonged to 2 epidemic lineages within genotype E, which may have the same origins as the strains reported in other part of China. CVA10 and CVB3, 2 pathogens that were previously infrequently detected, were identified as pathogens causing the HFMD outbreaks. This study underscores the need for detailed laboratory-based surveillances of HFMD in mainland China.     

Assessment of an enterovirus sewage surveillance system by comparison of clinical isolates with sewage isolates from milwaukee, wisconsin, collected august 1994 to december 2002

The quantity and serotypes of enteroviruses (EVs) in the influent of a local sewage treatment plant were compared to local clinical EV cases to determine if testing of sewage is adequate for an EV surveillance system. The study was carried out from August 1994 to December 2002. Monthly influent specimens were processed by organic flocculation, and dilutions of concentrate were inoculated onto a number of different cell types for virus isolation. EVs were detected in 88 of 100 monthly influent samples. Sewage EV titers were calculated by using software provided by the U.S. Environmental Protection Agency for most-probable-number determination. All 1,068 sewage EV isolates were further grouped (echovirus, coxsackievirus B, coxsackievirus A, or poliovirus) by cell culture host range analysis (growth pattern of isolates on passage to seven cell lines), and 39.0% of the 1,022 EV isolates categorized as non-poliovirus EVs were specifically serotyped. For clinical cases, primary virus isolation tests were performed on specimens submitted by local hospitals and EV isolates submitted by hospitals were serotyped. Clinical EVs were documented for 81 of the 100 months studied. In all, 694 EV isolates from clinical cases were serotyped. Annually, between 4 and 11 different serotypes of non-poliovirus EVs were identified in sewage and from 9 to 19 different non-poliovirus EV serotypes were identified from clinical specimens. Usually, the most commonly detected sewage EV serotypes were similar to the most commonly detected clinical serotypes; e.g., for 1997, echovirus 6 accounted for 53.1% of the typed sewage isolates and 39.4% of the clinical infections, while in 1998, echovirus 30 accounted for 50.0 and 46.1%, respectively. In 1999, 60.3% of the EVs from clinical cases and 79.7% of the sewage isolates were echovirus 11; in 2000, 33.3% of the EVs from clinical cases and 40.7% of the sewage isolates were coxsackievirus B5; and in 2001, 44.1% of the EVs from clinical cases and 36.2% of the sewage isolates were echovirus 13. Annual peaks of both sewage EV titers and clinical cases occurred in late summer or early fall. In some years, early spring sewage EVs portended some of the EVs that would predominate clinically during the following summer.     

Assessment of an Enterovirus Sewage Surveillance System by Comparison of Clinical Isolates with Sewage Isolates from Milwaukee, Wisconsin, Collected August 1994 to December 2002

The quantity and serotypes of enteroviruses (EVs) in the influent of a local sewage treatment plant were compared to local clinical EV cases to determine if testing of sewage is adequate for an EV surveillance system. The study was carried out from August 1994 to December 2002. Monthly influent specimens were processed by organic flocculation, and dilutions of concentrate were inoculated onto a number of different cell types for virus isolation. EVs were detected in 88 of 100 monthly influent samples. Sewage EV titers were calculated by using software provided by the U.S. Environmental Protection Agency for most-probable-number determination. All 1,068 sewage EV isolates were further grouped (echovirus, coxsackievirus B, coxsackievirus A, or poliovirus) by cell culture host range analysis (growth pattern of isolates on passage to seven cell lines), and 39.0% of the 1,022 EV isolates categorized as non-poliovirus EVs were specifically serotyped. For clinical cases, primary virus isolation tests were performed on specimens submitted by local hospitals and EV isolates submitted by hospitals were serotyped. Clinical EVs were documented for 81 of the 100 months studied. In all, 694 EV isolates from clinical cases were serotyped. Annually, between 4 and 11 different serotypes of non-poliovirus EVs were identified in sewage and from 9 to 19 different non-poliovirus EV serotypes were identified from clinical specimens. Usually, the most commonly detected sewage EV serotypes were similar to the most commonly detected clinical serotypes; e.g., for 1997, echovirus 6 accounted for 53.1% of the typed sewage isolates and 39.4% of the clinical infections, while in 1998, echovirus 30 accounted for 50.0 and 46.1%, respectively. In 1999, 60.3% of the EVs from clinical cases and 79.7% of the sewage isolates were echovirus 11; in 2000, 33.3% of the EVs from clinical cases and 40.7% of the sewage isolates were coxsackievirus B5; and in 2001, 44.1% of the EVs from clinical cases and 36.2% of the sewage isolates were echovirus 13. Annual peaks of both sewage EV titers and clinical cases occurred in late summer or early fall. In some years, early spring sewage EVs portended some of the EVs that would predominate clinically during the following summer.     

Sporadic Isolation of Sabin-Like Polioviruses and High-Level Detection of Non-Polio Enteroviruses during Sewage Surveillance in Seven Italian Cities,after Several Years of Inactivated Poliovirus Vaccination

Sewage surveillance in seven Italian cities between 2005 and 2008, after the introduction of inactivated poliovirus vaccination (IPV) in 2002, showed rare polioviruses, none that were wild-type or circulating vaccine-derived poliovirus (cVDPV), and many other enteroviruses among 1,392 samples analyzed. Two of five polioviruses (PV) detected were Sabin-like PV2 and three PV3, based on enzyme-linked immunosorbent assay (ELISA) and PCR results. Neurovirulence-related mutations were found in the 5′ noncoding region (5′NCR) of all strains and, for a PV2, also in VP1 region 143 (Ile > Thr). Intertypic recombination in the 3D region was detected in a second PV2 (Sabin 2/Sabin 1) and a PV3 (Sabin 3/Sabin 2). The low mutation rate in VP1 for all PVs suggests limited interhuman virus passages, consistent with efficient polio immunization in Italy. Nonetheless, these findings highlight the risk of wild or Sabin poliovirus reintroduction from abroad. Non-polio enteroviruses (NPEVs) were detected, 448 of which were coxsackievirus B (CVB) and 294 of which were echoviruses (Echo). Fifty-six NPEVs failing serological typing were characterized by sequencing the VP1 region (nucleotides [nt] 2628 to 2976). A total of 448 CVB and 294 Echo strains were identified; among those strains, CVB2, CVB5, and Echo 11 predominated. Environmental CVB5 and CVB2 strains from this study showed high sequence identity with GenBank global strains. The high similarity between environmental NPEVs and clinical strains from the same areas of Italy and the same periods indicates that environmental strains reflect the viruses circulating in the population and highlights the potential risk of inefficient wastewater treatments. This study confirmed that sewage surveillance can be more sensitive than acute flaccid paralysis (AFP) surveillance in monitoring silent poliovirus circulation in the population as well as the suitability of molecular approaches to enterovirus typing.     

Characterization of the Non-Polio Enterovirus Infections Associated with Acute Flaccid Paralysis in South-Western India

Non-polio enteroviruses (NPEVs) have been reported frequently in association with acute flaccid paralysis (AFP) cases during Polio Surveillance Programs (PSPs) worldwide. However, there is limited understanding on the attributes of their infections. This study reports characteristics of NPEVs isolated from AFP cases, investigated during PSPs held in 2009–2010, in Karnataka and Kerala states of south-western India having varied climatic conditions. NPEV cell culture isolates derived from stool specimens that were collected from 422 of 2186 AFP cases (<1–14 years age) and 17 of 41 asymptomatic contacts; and details of all AFP cases/contacts were obtained from National Polio Laboratory, Bangalore. The distribution of NPEV infections among AFP cases and circulation pattern of NPEV strains were determined by statistical analysis of the data. Genotyping of all NPEV isolates was carried out by partial VP1 gene sequencing and phylogenetic analysis. NPEV positive AFP cases were significantly higher in children aged <2 years; with residual paralysis; in summer months; and in regions with relatively hot climate. Genotyping of NPEVs identified predominance of human enteroviruses (HEV)-B species [81.9%—Echoviruses (E): 57.3%; coxsackieviruses (CV) B: 15%; numbered EVs: 8.9%; CVA9: 0.7%] and low levels of HEV-A [14.5%—CVA: 6%; numbered EVs: 8.5%] and HEV-C [3.6%—CVA: 2.6%; numbered EVs: 1%] species, encompassing 63 genotypes. EV76 (6.3%) and each of E3, CVB3 and E9 (4.97%) were found frequently during 2009 while E11 (6.7%), CVB1 (6.1%), E7 (5.1%) and E20 (5.1%) were detected commonly in 2010. A marked proportion of AFP cases from children aged <2 years; presenting with fever; and from north and south interior parts of Karnataka state was detected with E/numbered EVs than that found with CVA/CVB. This study highlights the extensive genetic diversity and diverse circulation patterns of NPEV strains in AFP cases from different populations and climatic conditions.     

Specific clinical, epidemiological patterns and laboratory diagnostics of enterovirus infection in the Republic of Belarus

The clinical and epidemiological patterns as well as the results of the laboratory verification of the outbreak of enterovirus infection (EVI) in Minsk during the period of summer-autumn, 2000, are presented. During this outbreak a variety of clinical forms were observed, the serous meningitis being prevalent (57.5%). Practically simultaneous occurrence of infection on the territory of all administrative districts of the city, the predominant involvement of children aged up to 14 years into the outbreak, a high proportion of simultaneous casualities in the multiple foci. A number of circulating enteroviruses (EV)--ECHO 30, ECHO 6 of three serotypes and Coxsackie B5--were simultaneously isolated from clinical material. EV of the same serotypes were isolated from tap drinking water, and neutralizing antibodies to these serotypes were often detected in the patients blood sera. Infectious EV were also present in samples of bottled water and in water reservoirs used for bathing. The routes of EV transmission and the improvement of EVI control are discussed.     

High Incidence of Mammalian Orthoreovirus Identified by Environmental Surveillance in Taiwan

Wild poliovirus (WPV) persists in diverse locales worldwide, spreading outward from endemic areas. In response to the international threat of WPV transmission and changes in the national vaccination policy, we established an environmental surveillance system to monitor the circulation of wild and vaccine-related poliovirus in Taiwan. From July 2012 to December 2013, we collected sewage specimens every month from 10 sewage treatment plants located throughout Taiwan. The specimens were concentrated by the two-phase separation method and then inoculated into L20B, RD, and A549 cells for virus isolation. Viral isolates were identified and serotyped by immunofluorescence assay or molecular analysis. A total of 300 sewage samples were collected, and the results showed 163 samples (54.3%) were positive for virus, and 268 isolates were identified. Among these, 75 samples (25%) were positive for enterovirus (EV), but no poliovirus was found. In addition, 92 isolates were identified as enteroviruses and the most common serotypes were coxsackievirus B4, coxsackievirus B3, and coxsackievirus B2. Interestingly, 102 (34%) and 82 (27.3%) specimens were positive for mammalian orthoreovirus (MRV) and adenovirus, respectively. This study confirmed that sewage surveillance can be a useful additional modality for monitoring the possible presence of wild-type or vaccine-derived poliovirus in wastewater, and can indicate the current types of viruses circulating in the population. Furthermore, since MRV was found in children with acute necrotizing encephalopathy and meningitis, the high incidence of MRV detected by environmental surveillance warrants further investigation.     

A One-Step,Triplex, Real-Time RT-PCR Assay for the Simultaneous Detection of Enterovirus 71, Coxsackie A16 and Pan-Enterovirus in a Single Tube

The recent, ongoing epidemic of hand, foot, and mouth disease (HFMD), which is caused by enterovirus infection, has affected millions of children and resulted in thousands of deaths in China. Enterovirus 71 (EV71) and coxsackie A16 (CA16) are the two major distinct pathogens for HFMD. However, EV71 is more commonly associated with neurologic complications and even fatalities. Therefore, simultaneously detecting and differentiating EV71 and CA16 specifically from other enteroviruses for diagnosing HFMD is important. Here, we developed a one-step, triplex, real-time RT-PCR assay for the simultaneous detection of EV71, CA16, and pan-enterovirus (EVs) in a single tube with an internal amplification control. The detection results for the serially diluted viruses indicate that the lower limit of detection for this assay is 0.001–0.04 TCID₅₀/ml, 0.02 TCID₅₀/ml, and 0.001 TCID₅₀/ml for EVs, EV71, and CA16, respectively. After evaluating known HFMD virus stocks of 17 strains of 16 different serotypes, this assay showed a favorable detection spectrum and no obvious cross-reactivity. The results for 141 clinical throat swabs from HFMD-suspected patients demonstrated sensitivities of 98.4%, 98.7%, and 100% for EVs, EV71, and CA16, respectively, and 100% specificity for each virus. The application of this one-step, triplex, real-time RT-PCR assay in clinical units will contribute to HFMD surveillance and help to identify causative pathogen in patients with suspected HFMD.     

Continuous detection of norovirus and astrovirus in wastewater in a coastal city of China in 2014–2016

Norovirus (NoV) and human astrovirus (HAstV) are important causative agents of acute gastroenteritis in children and adults. They are comprised of multiple genotypes and attention should be paid to genotype changes or emergence of new genetic variants. To study the prevalence and diversity of NoV GI, GII, and HAstV circulating in eastern China, we conducted a three-year environmental surveillance in a coastal city of Yantai. Thirty-six sewage samples were collected, processed, and examined for the presence of viral genomes by PCR. The results showed that NoV GI, GII, and HAstV were detected in all 36 samples. Six NoV GI genotypes, 11 NoV GII genotypes, and 5 HAstV serotypes were identified; GI.6, GII.17, and HAstV-5 were the most prevalent types, respectively. Persistent existence of NoV GII.17 Kawasaki 308 variant was observed during whole study period. Phylogenetic analysis reflected multiple transmission lineages in local population for both viruses. Our results reflect continuous presence of enteric viruses in sewage, improve our understanding on their molecular epidemiology, and demonstrate surveillance on sewage is an effective approach in understanding the local circulation of enteric viruses.     

Characterization of a Novel Enterovirus Serotype and an Enterovirus EV-B93 Isolated from Acute Flaccid Paralysis Patients

Non-polio enteroviruses (NPEVs) are among the most common viruses infecting humans worldwide. Most of these infections are asymptomatic but few can lead to systemic and neurological disorders like Acute Flaccid Paralysis (AFP). Acute Flaccid Paralysis is a clinical syndrome and NPEVs have been isolated frequently from the patients suffering from AFP but little is known about their causal relationship. The objective of this study was to identify and characterize the NPEV serotypes recovered from 184 stool samples collected from AFP patients in Federally Administered Tribal Areas (FATA) in north-west of Pakistan. Overall, 44 (95.6 %) isolates were successfully typed through microneutralization assay as a member of enterovirus B species including echovirus (E)-2, E-3, E-4, E-6, E-7, E-11, E-13, E-14, E-21 and E-29 while two isolates (PAK NIH SP6545B and PAK NIH SP1202B) remained untypeable. The VP1 and capsid regions analysis characterized these viruses as EV-B93 and EV-B106. Phylogenetic analysis confirmed that PAK NIH isolates had high genetic diversity and represent distinct genotypes circulating in the country. Our findings highlight the role of NPEVs in AFP cases to be thoroughly investigated especially in high disease risk areas, with limited surveillance activities and health resources.     

2013年大连市手足口病病原监测结果分析

目的通过对2013年大连市手足口病（HFMD）的病原进行鉴定,以了解其型别分布。方法采用realtime-PCR方法对754份标本进行肠道病毒（EV）通用引物和肠道病毒71型（EV71）、柯萨奇病毒A组16型（CVA16）、柯萨奇病毒A组6型（CVA6）型特异性引物检测,对EV通用引物检测结果为阳性,但EV71、CVA16和CVA6检测结果均为阴性的标本采用巢氏PCR进行肠道病毒VP1基因部分序列的扩增、测序和生物信息学分析以鉴定其型别。结果 2013年引起大连市HFMD的主要病原CVA6占44.30%（334/754）、CVA16占19.12%（114/754）、EV71占11.54%（87/754）,另有少数病例由CVA2、4、5、8型,CVB2、4型,ECHO9型及EV的其他型别引起。结论 CVA6取代EV71和CVA16成为2013年大连市HFMD病原的主要流行型别,后续应加强对HFMD病原的监测,全面了解其型别分布及毒株变异情况以更有效地控制疾病流行。     

肠道病毒B组山东地方株的基因型分布

为明确源自急性弛缓性麻痹(AFP)病例的HEV-B组病毒山东地方株的基因型分布,探讨其优势基因型的变迁与疾病暴发之间的关系,本研究对山东省1994年~2008年AFP监测系统分离到的HEV-B组病毒进行了VP1区核酸扩增和序列测定。序列测定结果显示HEV-B山东地方株共包括29种基因型,其中CVA 1种(CVA9),CVB 5种(CVB1~5),ECHO 20种以及新型肠道病毒EV73、75、97。其中ECHO11、CVB3、ECHO6、ECHO14、ECHO25是AFP监测系统中最常分离到的B组病毒。同源性比较显示,相同血清型HEV-B山东地方株型内核苷酸同源性最小75.4%,最大99.6%,与原型株核苷酸同源性最小73.8%,最大85.2%,但氨基酸变异不大。研究表明,不同基因型病毒具有不同的时间循环模式,相同基因型毒株内部根据其遗传距离的远近又可划分为不同的基因亚型,从而帮助确定HEV的传播途径和传播范围。     

Isolation and Characterization of a Type 2 Vaccine-Derived Poliovirus from Environmental Surveillance in China, 2012

Environmental surveillance of poliovirus on sewage has been conducted in Shandong Province, China since 2008. A type 2 vaccine-derived poliovirus (VDPV) with 7 mutations in VP1 coding region was isolated from the sewage collected in the city of Jinan in December 2012. The complete genome sequencing analysis of this isolate revealed 25 nucleotide substitutions, 7 of which resulted in amino acid alteration. No evidence of recombination with other poliovirus serotypes was observed. The virus did not lose temperature sensitive phenotype at 40°C. An estimation based on the evolution rate of the P1 coding region suggested that evolution time of this strain might be 160–176 days. VP1 sequence analysis revealed that this VDPV strain is of no close relationship with other local type 2 polioviruses (n = 66) from sewage collected between May 2012 and June 2013, suggesting the lack of its circulation in the local population. The person who excreted the virus was not known and no closely related virus was isolated in local population via acute flaccid paralysis surveillance. By far this is the first report of VDPV isolated from sewage in China, and these results underscore the value of environmental surveillance in the polio surveillance system even in countries with high rates of OPV coverage.     

Epidemiological, virological, and entomological characteristics of dengue from 1978 to 2009 in Guangzhou, China

To understand its unprecedented resurgence, we examined the epidemiological, virological, and entomological features of dengue in Guangzhou during 1978-2009. Cases reported to the Guangzhou Centre for Disease Control and Prevention and data from virological and entomological surveillance were analyzed from three periods: 1978-1988, 1989-1999, and 2000-2009. Although cases decreased over time: 6,649 (1978-1988) to 6,479 (1989-1999) to 2,526 (2000-2009), geographical expansion resulted in districts with an average incidence >2.5/100,000, increasing from five (1978-1988, 1989-1999) to seven (2000-2009). Age distribution (mean age: 34.9 years) provided a trend of increasing dengue incidence among adults, and there was a significantly higher incidence among men with a sex ratio of 1.15:1 (P<0.001). Cases occurred from May through November with a peak between August and October, and a long-term trend was characterized by a three to five-year cyclical pattern. The most frequently isolated serotypes were DENV-2 (1978-1988) and DENV-1 (1989-1999 and 2000-2009). Seasonal fluctuations in immature densities of Aedes albopictus (sole transmission vector in Guangzhou) were consistent with the dengue seasonality. After a 30-year apparent absence, DENV-3 had reemerged in 2009. The current epidemiological situation is highly conducive to periodic dengue resurgences. Thus, a high degree of surveillance and strict control measures in source reduction should be maintained.     

Decreased serologic response in vaccinated military recruits during 2011 correspond to genetic drift in concurrent circulating pandemic A/H1N1 viruses

Background

Population-based febrile respiratory illness surveillance conducted by the Department of Defense contributes to an estimate of vaccine effectiveness. Between January and March 2011, 64 cases of 2009 A/H1N1 (pH1N1), including one fatality, were confirmed in immunized recruits at Fort Jackson, South Carolina, suggesting insufficient efficacy for the pH1N1 component of the live attenuated influenza vaccine (LAIV).

Methodology/Principal Findings

To test serologic protection, serum samples were collected at least 30 days post-vaccination from recruits at Fort Jackson (LAIV), Parris Island (LAIV and trivalent inactivated vaccine [TIV]) at Cape May, New Jersey (TIV) and responses measured against pre-vaccination sera. A subset of 78 LAIV and 64 TIV sera pairs from recruits who reported neither influenza vaccination in the prior year nor fever during training were tested by microneutralization (MN) and hemagglutination inhibition (HI) assays. MN results demonstrated that seroconversion in paired sera was greater in those who received TIV versus LAIV (74% and 37%). Additionally, the fold change associated with TIV vaccination was significantly different between circulating (2011) versus the vaccine strain (2009) of pH1N1 viruses (ANOVA p value = 0.0006). HI analyses revealed similar trends. Surface plasmon resonance (SPR) analysis revealed that the quantity, IgG/IgM ratios, and affinity of anti-HA antibodies were significantly greater in TIV vaccinees. Finally, sequence analysis of the HA1 gene in concurrent circulating 2011 pH1N1 isolates from Fort Jackson exhibited modest amino acid divergence from the vaccine strain.

Conclusions/Significance

Among military recruits in 2011, serum antibody response differed by vaccine type (LAIV vs. TIV) and pH1N1 virus year (2009 vs. 2011). We hypothesize that antigen drift in circulating pH1N1 viruses contributed to reduce vaccine effectiveness at Fort Jackson. Our findings have wider implications regarding vaccine protection from circulating pH1N1 viruses in 2011–2012.