Mitigating an undesirable immune response of inherent susceptibility to cutaneous leishmaniosis in a mouse model: the role of the pathoantigenic HISA70 DNA vaccine

ABSTRACT: Leishmania major is the major cause of cutaneous leishmaniosis (CL) outside of the Americas. In the present study we have cloned six Leishmania genes (H2A, H2B, H3, H4, A2 and HSP70) into the eukaryotic expression vector pCMVbeta-m2a, resulting in pCMV-HISA70m2A, which encodes all six pathoantigenic proteins as a single polyprotein. This expression plasmid has been evaluated as a novel vaccine candidate in the BALB/c mouse model of CL. The DNA vaccine shifted the immune response normally induced by L. major infection away from a Th2-specific pathway to one of basal susceptibility. Immunization with pCMV-HISA70m2A dramatically reduced footpad lesions and lymph node parasite burdens relative to infected control mice. Complete absence of visceral parasite burden was observed in all 12 immunized animals but not in any of the 24 control mice. Moreover, vaccinated mice produced large amounts of IFN-gamma, IL-17 and NO at 7 weeks post-infection (pi), and they showed lower arginase activity at the site of infection, lower IL-4 production and a weaker humoral immune response than infected control mice. Taken together, these results demonstrate the ability of the HISA70 vaccine to shift the murine immune response to L. major infection away from an undesirable, Th2-specific pathway to a less susceptible-like pathway involving Th1 and Th17 cytokine profiles.     

Testis-specific histone variants H2AL1/2 rapidly disappear from paternal heterochromatin after fertilization

Before fertilization, the genome packaging of male and female gametes is very different. Indeed, whereas the female haploid genome is associated with histones in a somatic-like chromatin structure, most of the male genome is tightly bound to protamines. However, it has recently been demonstrated that the pericentric heterochromatin regions of the male genome are associated with specific H2A-like histone variants, named H2AL1 and H2AL2, suggesting a heterogeneous organization. The fate and role of the sex-specific genome packaging transmitted by germinal cells to the embryo are not well understood. The aim of the present study was to follow reprogramming of the parental genomes in early embryos after in vivo fertilization. We show here that two typical epigenetic markers, trimethylated lysine 9 of histone H3 (TriMethylH3K9) and acetylated H4, are asymmetrically distributed between the parental genomes in one-cell mouse embryos, confirming data from embryos obtained after intracytoplasmic sperm injection (ICSI) or in vitro fertilization (IVF). Indeed, whereas the maternal genome is highly enriched with trimethylH3K9, this mark is not detected in the paternal genome. On the contrary, histone H4 incorporated in the paternal genome is highly acetylated at an early stage, while in the maternal pronucleus, the level of acetylated H4 remains low in early one-cell embryos and becomes enriched at a later stage. Moreover, our results suggest a very quick disappearance of histone H2A variants H2AL1 and H2Al2 from the paternal pericentric heterochromatin regions after sperm-egg fusion.     

DNA vaccine encoding avian influenza virus H5 and Esat-6 of Mycobacterium tuberculosis improved antibody responses against AIV in chickens

The H5 gene of avian influenza virus (AIV) strain A/chicken/Malaysia/5744/2004(H5N1) was cloned into pcDNA3.1 vector, and Esat-6 gene of Mycobacterium tuberculosis was fused into downstream of the H5 gene as a genetic adjuvant for DNA vaccine candidates. The antibody level against AIV was measured using enzyme-linked immunosorbent assay (ELISA) and haemagglutination inhibition (HI) test. Sera obtained from specific-pathogen-free chickens immunized with pcDNA3.1/H5 and pcDNA3.1/H5/Esat-6 demonstrated antibody responses as early as 2 weeks after the first immunization. Furthermore, the overall HI antibody titer in chickens immunized with pcDNA3.1/H5/Esat-6 was higher compared to the chickens immunized with pcDNA3.1/H5 (p < 0.05). The results suggested that Esat-6 gene of M. tuberculosis is a potential genetic adjuvant for the development of effective H5 DNA vaccine in chickens.     

Histone H4 Modification During Mouse Spermatogenesis

The core histone is composed of four proteins (H2A, H2B, H3 and H4). Investigation of the modification patterns of histones is critical to understanding their roles in biological processes. Although histone modification is observed in multiple cells and tissues, little is known about its function in spermatogenesis. We focused on the modification patterns of histone H4 during murine spermatogenesis. We demonstrated that the individual N-terminal sites of H4 show different modification patterns during the differentiation of male germ cells. The methylation pattern varied depending on the residues that were mono-, di-, or tri-methylated. All the H4 modifications were high during the meiotic prophase, suggesting that histone H4 modification plays an important role during this stage of spermatogenesis. Elongating spermatids showed increased acetylation of histone H4, which may be associated with a histone-to-protamine substitution. Our results provide further insight into the specific relationship between histone H4 modification and gene expression during spermatogenesis, which could help to elucidate the epigenetic disorders underlying male infertility.     

Involvement of histone H2B monoubiquitination in the regulation of mouse preimplantation development

Histone H2B monoubiquitination (H2Bub1) plays an important role in developmental regulation in various vertebrate species. However, the role of H2Bub1 in mammalian preimplantation development remains unclear. In the present study, we examined the role of H2Bub1 in the regulation of mouse preimplantation development. Based on immunocytochemical analysis using an anti-H2Bub1 antibody, no H2Bub1 signal was detected in the metaphase chromosomes of unfertilized oocytes or the pronuclei of early 1-cell stage embryos, but a weak signal was observed in late 1-cell stage embryos. The signal increased after cleavage into the 2-cell stage, and thereafter a strong signal was observed until the blastocyst stage. To assess the significance of H2Bub1 in the regulation of preimplantation development, RNF20 (an H2B-specific ubiquitin E3 ligase) was knocked down using small interfering RNA (siRNAs). In embryos treated with siRNA, the levels of Rnf20 mRNA and H2Bub1 decreased at the 4-cell and morula stages. Although these embryos developed normally until the morula stage, only one-third developed into the blastocyst stage. These results suggested that H2Bub1 is involved in the regulation of preimplantation development.     

绵羊肺炎支原体pcDNA3.1-TBP30-Hsp70融合表达质粒的构建及对小鼠细胞免疫应答的影响

为探究绵羊肺炎支原体（Mycoplasma ovipneumoniae,Mo）pcDNA3.1-TBP30-Hsp70融合表达质粒对小鼠细胞免疫应答影响,本试验构建了绵羊肺炎支原体pcDNA3.1-TBP30-Hsp70融合表达质粒。用已构建的pMD19T-P30和pMD19-Hsp70质粒为模板,采用基因定点突变（SDM）原理设计引物,应用SOE-PCR扩增目的基因片段,并将其定向克隆至表达载体pcDNA3.1（+）,构建重组质粒pcDNA 3.1（+）-TBP30和融合重组质pcDNA3.1（+）-TBP30-Hsp70。使用pcDNA3.1-TBP30、pcDNA3.1-TBP30-Hsp70、pcDNA3.1（+）和Elution Buffer对小鼠进行免疫,应用ELISA试剂盒检测小鼠血清中细胞因子白细胞介素-2（IL-2）、IL-4、干扰素-γ（INF-γ）分泌水平。结果显示,pcDNA3.1-TBP30-Hsp70酶切后可见大小分别约为1 413 bp的目的基因片段和5 400 bp的载体条带。与空白对照组和pcDNA3.1（+）组相比,免疫重组质粒组均可引起小鼠血清中细胞因子INF-γ、IL-2和IL-4分泌水平的增强,与空白对照组和pcDNA3.1（+）组相比差异显著或极显著（P<0.05;P<0.01）;而空白对照组和空质粒组之间差异不显著（P>0.05）;免疫pcDNA3.1-TBP30和pcDNA3.1-TBP30-Hsp70组小鼠血清IL-2、INF-γ和IL-4终分泌量增加,表明重组质粒组可刺激小鼠血清中IL-2、INF-γ和IL-4的变化,并且在时间上都呈现出先增多后减少的规律。本试验结果表明,重组质粒pcDNA3.1（+）-TBP30-Hsp70免疫小鼠后,IL-2和INF-γ分泌水平的升高,增强了机体的细胞免疫功能,进而调节机体细胞免疫影响T细胞和巨噬细胞的分泌,从而提高机体细胞免疫能力;IL-4分泌水平升高,促进机体Th2向Th1分化,维持Th1的优势状态,增强了机体的细胞免疫功能。本试验结果为绵羊肺炎支原体基因工程疫苗的研制提供了参考依据。     

Induction of a protective immune response against swine Chlamydophila abortus infection in mice following co-vaccination of omp-1 DNA with recombinant MOMP

Chlamydophila abortus is the causative agent of abortion in pigs and pregnant women. Seroconversion rates were arranged from 11% to 80% in piglets and sows in China. These very high rates illustrate the scale of the problem in China and highlight the urgent need for the development of a C. abortus vaccine. An efficacious anti-chlamydial vaccine should induce not only strong mucosal and systemic T-helper type 1 (Th1) immune response but also give a humoral response that enhances Th1 activation following infection. In order to evaluate an active immune response of a combination of the major outer membrane protein (MOMP) DNA- and protein-based vaccines, 54 BALB/c mice were randomly assigned to six groups and inoculated intramuscularly with: (i) 100 microg pcDNA::MOMP, (ii) 10 microg r-MOMP, (iii) primed with 100 microg pcDNA::MOMP and boosted with 10 microg r-MOMP, (iv) primed-boosted with a combination of pcDNA::MOMP and r-MOMP simultaneously, (v) live-attenuated 1B vaccine, (vi) 100 microg pcDNA3.1 vector. All animals were vaccinated two times at 14 days intervals. Results showed that mice given DNA and r-MOMP induced higher antibody levels, higher T cells proliferation and an elevated level of chlamydial clearance in spleen, which was equivalent to the clearance of 1B vaccine. Mice administrated the DNA-primed/MOMP-boosted approach elicited moderate antibody levels, less T-lymphocyte proliferation and lower chlamydial clearance as compared with 1B vaccine. Co-immunization with DNA- and r-MOMP vaccine may provide novel ways for active immunization strategy against swine C. abortus.     

Improved immune responses against avian influenza virus following oral vaccination of chickens with HA DNA vaccine using attenuated Salmonella typhimurium as carrier

This study evaluates the immune responses of single avian influenza virus (AIV) HA DNA vaccine immunization using attenuated Salmonella enterica sv. Typhimurium as an oral vaccine carrier and intramuscular (IM) DNA injection. One-day-old specific-pathogen-free (SPF) chicks immunized once by oral gavage with 10(9) Salmonella colony-forming units containing plasmid expression vector encoding the HA gene of A/Ck/Malaysia/5858/04 (H5N1) (pcDNA3.1.H5) did not show any clinical manifestations. Serum hemagglutination inhibition (HI) titer samples collected from the IM immunized chickens were low compared to those immunized with S. typhimurium.pcDNA3.1.H5. The highest average antibody titers were detected on day 35 post immunization for both IM and S. typhimurium.pcDNA3.1.H5 immunized groups, at 4.0±2.8 and 51.2±7.5, respectively. S. typhimurium.pcDNA3.1.H5 also elicited both CD4(+) and CD8(+) T cells from peripheral blood mononuclear cells (PBMCs) of immunized chickens as early as day 14 after immunization, at 20.5±2.0 and 22.9±1.9%, respectively. Meanwhile, the CD4(+) and CD8(+) T cells in chickens vaccinated intramuscularly were low at 5.9±0.9 and 8.5±1.3%, respectively. Immunization of chickens with S. typhimurium.pcDNA3.1.H5 enhanced IL-1β, IL-12β, IL-15 and IL-18 expressions in spleen although no significant differences were recorded in chickens vaccinated via IM and orally with S. typhimurium and S. typhimurium.pcDNA3.1. Hence, single oral administrations of the attenuated S. typhimurium containing pcDNA3.1.H5 showed antibody, T cell and Th1-like cytokine responses against AIV in chickens. Whether the T cell response induced by vaccination is virus-specific and whether vaccination protects against AIV infection requires further study.     

Different evolutionary trends of swine H1N2 influenza viruses in Italy compared to European viruses

European H1N2 swine influenza viruses (EU H1N2SIVs) arose from multiple reassortment events among human H1N1, human H3N2, and avian influenza viruses. We investigated the evolutionary dynamics of 53 Italian H1N2 strains by comparing them with EU H1N2 SIVs. Hemagglutinin (HA) phylogeny revealed Italian strains fell into four groups: Group A and B (41 strains) had a human H1 similar to EU H1N2SIVs, which probably originated in 1986. However Group B (38 strains) formed a subgroup that had a two-amino acid deletion at positions 146/147 in HA. Group C (11 strains) contained an avian H1 that probably originated in 1996, and Group D (1 strain) had an H1 characteristic of the 2009 pandemic strain. Neuraminidase (NA) phylogeny suggested a series of genomic reassortments had occurred. Group A had an N2 that originated from human H3N2 in the late 1970s. Group B had different human N2 that most likely arose from a reassortment with the more recent human H3N2 virus, which probably occurred in 2000. Group C had an avian-like H1 combined with an N2 gene from one of EU H1N2SIVs, EU H3N2SIVs or Human H3N2. Group D was part of the EU H3N2SIVs clade. Although selection pressure for HA and NA was low, several positively selected sites were identified in both proteins, some of which were antigenic, suggesting selection influenced the evolution of SIV. The data highlight different evolutionary trends between European viruses and currently circulating Italian B strains and show the establishment of reassortant strains involving human viruses in Italian pigs.     

H9N2亚型禽流感病毒中和单克隆抗体的制备与应用

为建立H9N2亚型禽流感病毒（Avian influenza virus,AIV）免疫层析快速检测技术,本研究以差速离心法纯化H9N2亚型AIV免疫BALB/c小鼠,将免疫小鼠脾细胞与骨髓瘤细胞SP2/0进行细胞融合和HAT选择性培养;以H9N2亚型AIV感染MDCK细胞建立异源免疫过氧化物酶单层细胞试验（IPMA）的单克隆抗体检测方法,通过对杂交瘤细胞的IPMA筛选和连续克隆化筛选鉴定抗H9N2亚型AIV中和性单克隆抗体;以胶体金标记HA单克隆抗体,配对HA单克隆抗体和羊抗小鼠IgG为检测线和质控线,制备H9N2亚型AIV快速检测试纸条,测定其特异性和敏感性。结果显示,获得了11株稳定分泌抗H9N2亚型AIV单克隆抗体的杂交瘤细胞,其单克隆抗体腹水IPMA效价在1.28×10^-4至2.56×10^-5之间。单克隆抗体3A2、5H6、6B8、7E10和9G12血凝抑制试验（HI）显示血凝抑制活性,其（HI）效价在6log2~9log2之间。单克隆抗体3A2、6B8和9G12在病毒中和试验中对H9N2亚型AIV有显著病毒中和活性,中和效价分别1∶6 400、1∶25 600和1∶25 600。Western blotting结果提示,该中和单克隆抗体识别HA蛋白线性抗原表位。利用配对单克隆抗体3A2和9G12研制的H9N2亚型AIV检测试纸条检测H9N2亚型AIV尿囊液的效价为9log2,灵敏度与经典血凝试验（HA）相当,与其他亚型AIV （H1、H3、H5、H7）,以及新城疫病毒和鸡传染性法氏囊病病毒等相关病毒均无交叉反应。本研究制备了具有病毒中和活性的抗H9N2亚型AIV单克隆抗体,并初步研制了H9N2亚型AIV检测试纸条,为H9N2亚型AIV新型疫苗研制和快速检测奠定良好的研究基础。     

The occurrence and transmission characteristics of airborne H9N2 avian influenza virus

To better understand the transmission route of H9N2 avian influenza virus (AIV), two duplicate trials were conducted to observe the process of aerosol infection and direct contact in specific pathogen free chickens. Fifteen chickens (G1) were inoculated with H9N2 AIV and housed together with another 15 chickens (G2) in the same positive-negative-pressure isolator (A). Fifteen chickens (G3) were bred in another isolator (B) which was connected with A so that air could flow unidirectionally from A to B. Air, oropharyngeal and cloacal swabs, and blood samples were collected for the detection of aerosolized virus, virus shedding, and seroconversion. AIV aerosols were initially detected at day 2-3 post inoculation (dpi), reaching peak concentrations at 7 dpi. Virus shedding was detected in all chickens of G2, but only in a part in G3 (T1: 87%, T2: 80%). Antibodies were initially detected at 4-5 dpi, peaking at 14-21 dpi. The results showed that H9N2 AIV could be transmitted by both aerosol exposure and direct contact.     

The relationship between some plasma clearance methods for estimation of glomerular filtration rate in dogs with pyometra

The purpose of the present study was to compare different pharmacokinetic models for estimation of glomerular filtration rate (GFR) in 50 dogs with pyometra. GFR was estimated by plasma clearance (CLplasma) of iohexol by four 1-compartment methods (CL1c), a 2-compartment method (CL2c), and the trapezoidal method (CLtr). Regression analysis was performed to establish correction formulas for prediction of CLtr from the CL1c values and to find optimal times of sampling. Standardization of clearance values to body weight (kg), body surface area (m2) and extracellular fluid volume (ECFV) was compared by ranking of values. CLtr and CL2c values were similar, whereas CL1c overestimated CLtr. CLtr could be predicted from 2 samples at 2 and 3 hours after injection, using the formula CLtr = 4.52 + 0.84CL1c - 0.00080(CL1c)2 (R2 = .97). Similar relationships were found when sampling at 2 and 4 hours or at 2, 3 and 4 hours after injection, whereas predictions from the 3- and 4-hour estimates were not optimal (R2 = .79). The 2-sample methods for calculating GFR/ECFV generally produced unreliable predictions of the complete curve GFR/ECFV values. For some dogs, the choice of standardization procedure substantially changed the apparent level of renal function relative to other dogs in the study. We conclude that by applying an appropriate correction formula, GFR may be estimated using 2 blood samples at 2 and 3, or 2 and 4 hours after injection of iohexol when renal function is normal or moderately reduced. The method of standardizing the analysis with respect to body size may influence interpretation of the results substantially.     

捻转血矛线虫免疫调节型DNA疫苗的构建及在山羊体内表达研究

为构建免疫调节型DNA疫苗,将山羊IL-2基因分别与捻转血矛线虫H11-1、H11-2和H11-3基因串联构建融合表达载体pcDNA/IL-2-H11-1、pcDNA/IL-2-H11-2和pcDNA/IL-2-H11-3。为检测疫苗在山羊体内的表达情况,将纯化的疫苗质粒肌肉注射山羊后取注射部位肌肉组织,于首次免疫7 d后和二次免疫10 d后分别用RT-PCR和Western Blot等方法检测H11抗原的转录和翻译情况。结果发现H11基因和IL-2基因均能在注射部位肌肉获得转录和翻译。     

Functions of histone H2A variants

One way that cells alter their chromatin structure is by incorporating histone variants into their nucleosomes. Unlike canonical histones, which are deposited behind the replication fork during the S‐phase of cell division, the accumulation of histone variants is independent of DNA replication. However, among the histone variants, H2A variants play an important role in DNA replication, damage repair, recombination and gene expression. This paper provides a review of H2A histone variants and their functions, exchange in the chromatin and depositional modes by specific chaperones.     

重配H9N1亚型流感病毒感染性克隆的构建及鉴定

为了研究禽流感病毒的反向遗传,试验采用霍夫曼发明的8质粒拯救系统,将分离得到的AIV Isolate3(H9N2)基因组,通过RT-PCR得到HA基因,并克隆到以pcDNA3质粒为骨架自行构建的双向转录/表达载体pHW2008上,得到HA转录/表达质粒,再将HA表达质粒与构建好的包含A/Puerto Rico/8/34(H1N1)7个内部基因双向转录/表达质粒共转染人肾上皮细胞(293T)与犬肾细胞(MDCK)混养细胞。结果表明:试验成功构建了重配H9N1亚型流感病毒减毒株。     

CRISPR/Cas13d介导猪胎儿成纤维细胞SUV39H1/SUV39H2基因敲降

研究旨在利用CRISPR/Cas13d系统对猪胎儿成纤维细胞（PEF）中的胚胎发育相关基因SUV39H1/SUV39H2进行RNA水平的敲降，从而在猪上建立CRISPR/Cas13d介导的基因敲降系统。根据SUV39H1、SUV39H2基因的编码序列各设计3个靶向编码链的sgRNAs，并以单链寡核苷酸的形式合成，退火后与BspQⅠ线性化的sgRNA表达载体进行连接，构建SUV39H1-sgRNA和SUV39H2-sgRNA表达载体，用Sanger软件进行测序；将Cas13d表达载体和靶向SUV39H1/SUV39H2基因的sgRNA载体按照1∶1、1∶2、1∶4、2∶1和4∶1比例转染猪胎儿成纤维细胞，48 h后收集细胞，用流式细胞术分选检测细胞转染效率，用半定量PCR和实时荧光定量PCR检测敲降效率；用半定量PCR和免疫荧光检测敲降SUV39H1/SUV39H2基因后，靶基因转录水平及组蛋白H3K9me3水平的变化。测序结果表明，针对2个基因设计的各3条sgRNAs均成功连入载体中；流式细胞术分选结果显示，转染效率约70%；半定量PCR结果表明，与对照组相比，3个sgRNAs均极显著降低了SUV39H1和SUV39H2基因的表达（P<0.01），其中SUV39H1-sgRNA-2和SUV39H2-sgRNA-1均可使SUV39H1和SUV39H2的表达降低50%；Cas13d∶sgRNA为1∶1、1∶2和1∶4组细胞的存活率高于2∶1和4∶1组；实时荧光定量PCR结果表明，Cas13d∶sgRNA为1∶2、1∶4、2∶1和4∶1组敲降效率均显著高于1∶1组（P<0.05），且Cas13d∶sgRNA为1∶2组敲降效率最高（70%）。半定量PCR结果显示，转染SUV39H1-sgRNA-2和SUV39H2-sgRNA-1极显著降低SUV39H1和SUV39H2的表达，表达量为对照组的25%~30%（P<0.01）。免疫荧光检测结果表明，敲降SUV39H1和SUV39H2基因后，组蛋白H3K9me3水平显著降低（P<0.05）。因此，本研究利用CRISPR/Cas13d系统在猪胎儿成纤维细胞中成功敲降SUV39H1和SUV39H2，并下调其催化的H3K9me3水平。     

猪流感病毒H1N1、H1N2和H3N2亚型多重RT-PCR诊断方法的建立

对我国分离到的猪流感病毒和GenBank数据库中已有的猪流感病毒H1N1、H1N2和H3N2亚型毒株的HA、NA基因核苷酸序列进行分析,分别选出各个病毒亚型HA和NA基因中高度保守且特异的核苷酸区域,设计扩增猪流感病毒H1和H3、N1和N2亚型的2套多重PCR特异性引物,建立了猪流感H1N1、H1N2和H3N2亚型病毒多重RT-PCR诊断方法。采用该方法对H1N1、H1N2、H3N2亚型猪流感病毒标准参考株进行RT-PCR检测,结果均呈阳性,对扩增得到的片段进行序列测定和BLAST比较,表明为目的基因片段。其它几种常见猪病病毒和其它亚型猪流感病毒的RT-PCR扩增结果都呈阴性。对107EID50/0.1mL病毒进行稀释,提取RNA进行敏感性试验,RT-PCR最少可检测到102EID50的病毒量核酸。对40份阳性临床样品的检测结果是H1N1、H1N2和H3N2亚型分别为16份、1份和20份,其它3份样品同时含有H1N1和H3N2亚型猪流感病毒,和鸡胚分离病毒结果100%一致。试验证明建立的猪流感病毒H1N1、H1N2和H3N2亚型多重RT-PCR诊断方法是一种特异敏感的诊断方法,可用于临床样品的早期快速诊断和分型。     

Evaluation of transmission of swine influenza type A subtype H1N2 virus in seropositive pigs

OBJECTIVE: To examine clinical signs, virus infection and shedding, and transmission of swine influenza virus (SIV) subtype H1N2 among seropositive pigs. ANIMALS: Eighteen 3-week-old pigs with maternal antibodies against SIV subtypes H1N1, H3N2, and H1N2. PROCEDURE: Ten pigs (principal) were inoculated intranasally with subtype H1N2 and 2 groups of contact pigs (n = 4) each were mixed with principal pigs on day 7 (group 1) or 28 (group 2). Two principal pigs each were necropsied on days 4, 14, 21, 28, and 42 days after inoculation. Four pigs in each contact group were necropsied 35 and 14 days after contact. Virus excretion was evaluated after inoculation or contact. Lung lesions and the presence of SIV in various tissues were examined. RESULTS: Mild coughing and increased rectal temperature were observed in principal pigs but not in contact pigs. Nasal virus shedding was detected in all principal pigs from day 2 for 3 to 5 days, in group 1 pigs from day 2 for 4 to 9 days after contact, and in group 2 pigs from day 4 for 2 to 6 days after contact. Trachea, lung, and lymph node specimens from infected pigs contained virus. Antibody titers against all 3 subtypes in all pigs gradually decreased. CONCLUSIONS AND CLINICAL RELEVANCE: Protection from viral infection and shedding was not observed in pigs with maternal antibodies, but clinical disease did not develop. Vaccination programs and good management practices should be considered for control of SIV subtype H1N2 infection on swine farms.