Myofibroblastic fibrosarcoma with multifocal osseous metaplasia at the site of equine influenza vaccination

We describe a fibrosarcoma in a 12-year-old Quarterhorse × Arabian gelding as a sequela to equine influenza vaccination. Shortly after the second vaccination, swelling at the site was noticed by the owner and it continued to increase in size over the following 6 months. Biopsy of the mass indicated a fibrosarcoma had developed at the vaccination site. It was approximately 20 cm in diameter and elevated well above the level of the skin. There was no clinical evidence of metastases to the lungs or local lymph nodes. Surgical resection of the mass was performed and the wound healed by first and second intention. Histopathological examination and immunohistochemical staining confirmed a myofibroblastic fibrosarcoma with multifocal osseous metaplasia. To the authors' knowledge, this is the first equine case of a vaccine-associated fibrosarcoma.     

Antibody responses after vaccination against equine influenza in the Republic of Korea in 2013

In this study, antibody responses after equine influenza vaccination were investigated among 1,098 horses in Korea using the hemagglutination inhibition (HI) assay. The equine influenza viruses, A/equine/South Africa/4/03 (H3N8) and A/equine/Wildeshausen/1/08 (H3N8), were used as antigens in the HI assay. The mean seropositive rates were 91.7% (geometric mean antibody levels (GMT), 56.8) and 93.6% (GMT, 105.2) for A/equine/South Africa/4/03 and A/equine/Wildeshausen/1/08, respectively. Yearlings and two-year-olds in training exhibited lower positive rates (68.1% (GMT, 14) and 61.7% (GMT, 11.9), respectively, with different antigens) than average. Horses two years old or younger may require more attention in vaccination against equine influenza according to the vaccination regime, because they could be a target of the equine influenza virus.     

Accelerated vaccination schedule provides protective levels of antibody and complete herd immunity to equine influenza

Reasons for performing study: During the 2007 Australian equine influenza (EI) outbreak, an accelerated primary course 14 day intervaccination schedule was proposed, but not widely implemented. Expert opinion was divided as to the efficacy of such a schedule given the lack of published data. This study determined the level and duration of humoral immunity following administration of a recombinant canarypox‐vectored vaccine (ALVAC‐EIV) with a primary intervaccination interval of 14 days and booster at 105 days. Objectives: To examine whether protective levels of immunity of adequate duration were achieved following a primary course reduced from a minimum interval of 28 to 14 days. Antibody responses to 2 H3N8 American lineage virus strains (including A/equine/Sydney/6085/2007) were assessed and compared to previous challenge studies using ALVAC‐EIV at conventional intervaccination intervals. Methods: Fourteen Thoroughbred horses and 2 ponies from a rural racehorse training property in Victoria, Australia, were vaccinated with ALVAC‐EIV on Days 0, 14 and 105. Serial blood samples were collected over the next 32 weeks and tested with haemagglutination inhibition and single radial haemolysis (SRH) in full assays to evaluate the serological response. Results: All horses and ponies responded to the accelerated ALVAC‐EIV vaccination schedule. Mean SRH antibodies remained above those consistent with clinical protection for the duration of the study period. All vaccinates demonstrated high SRH antibodies 14 days following V2, thereby achieving 100% herd immunity to homologous viral challenge. Conclusions: An accelerated vaccination schedule conferred long‐lasting protective antibody levels despite a >50% reduction in the recommended V1–V2 interval. Potential relevance: High levels of rapidly acquired herd immunity are critical in containing an outbreak of such a highly contagious pathogen as EIV. In a strategic vaccination programme, it is important that horses remain protected for sufficient time to allow control programmes to succeed. An accelerated 14 day primary course intervaccination interval and booster at 105 days achieves both of these objectives.     

马流感A/马/京防/74-1(H7N7)毒株HA基因的序列分析

流感病毒(Influenza Virus)根据血凝素(HA)和神经氨酸酶(NA)两种表面抗原蛋白分为不同的亚型,马流感I型(H7N7)和Ⅱ型(H3N8)是其中比较重要的两个亚型.本研究应用无特定病原体(SPF)鸡胚增殖马流感病毒A/马/京防/74-1(H7N7)毒株,TRIzol LS Reagent提取病毒RNA,RT-PCR扩增HA基因全片段,克隆到PMD18-T载体上,并进行了鉴定和序列测定.所获得的HA基因片段长1 727 bp,编码563个氨基酸残基.根据推导的氨基酸序列进行预测,有7个潜在的糖基化位点和16个半胱氨酸残基,通过序列分析推断,A/马/京防/74-1(H7N7)株病毒的HA来源于禽类,是一株通过基因重排出现的重组病毒.     

湖北株H3N8亚型马流感病毒HA基因的序列测定及其HA蛋白遗传特性分析

2008年从湖北省分离到1株H3N8亚型马流感病毒A/equine/Hubei/6/08。以2002年美国KENTUKY株为模板设计HA基因测序引物,进行RT-PCR,然后测定该分离株的HA基因核苷酸序列。经NCBI上Blast同源性比较发现,与A/equine/Newmarket/5/2003(H3N8)同源性较高为98.7%。HA蛋白遗传进化分析表明该毒株隶属于H3N8亚型马流感病毒中的美洲系福罗里达亚系。该株与OIE现在推荐的疫苗候选株A/equine/Kentuck-y/5/2002(H3N8)HA1蛋白氨基酸序列比对发现有3处氨基酸替换位点;与OIE以往推荐的疫苗候选株A/e-quine/Kentucky/1/1994(H3N8)比对发现有11处氨基酸替换位点。研究结果表明该分离株可作为中国研制马流感疫苗的候选株。     

马流感病毒A/马/青海1/94株亚型鉴定及其HA基因序列特征

本试验用AI标准阳性分型血清对我国马流感病毒A／马/青海/1／94进行了血凝素(H)和神经氨酸酶(N)的鉴定，并与马流感病毒吉林株、黑龙江株、北京株及国际标准株A／切ukx／Mgxd／2／63进行了对比，结果显示，1944年在我国青海省暴发的马流感病毒的亚型为H3N8；以反转录。聚合酶链式反应(RT-PCR)扩增该株的血凝素基因，并克隆到pGEM-Teasy载体上，采用双脱氧末端终止法测定该cDNA片段共1738个核苷酸序列，并推导出其编码的565个氨基酸的序列。利用Genbank blast和基因进化树分析软件分析各毒株之间的亲缘关系，发现A／马/青海/1/94与1992年香港马流感分离株存在较近的亲缘关系。     

First recovery of A/equine/Fontainebleau/1/79 influenza viruses in Italy

In Italy epizootics of equine influenza often occur, but no virus isolation has been reported since 1971. This paper describes the antigenic and biochemical characterization of two equine influenza viruses isolated in Italy from 1985 to 1989. The virus isolates were shown to differ antigenically from earlier strains of the same subtype, A/equine/Miami/1/63 (H3N8). Monoclonal antibody analysis showed that the haemagglutinins of these strains were serologically indistinguishable from A/equine/Fontainebleau/1/79, a variant of A/equine/Miami, never isolated in Italy before. One of the two virus isolates was obtained from a horse immunized with a bivalent inactivated influenza vaccine, not containing A/equine/Fontainebleau/79 antigens.

The vaccine failure underlines the importance of antigenic relatedness between currently circulating viruses and vaccine strains. Therefore, to improve the protection afforded by equine immunization, the vaccine composition should be decided according to the results of a virological surveillance activity, systematically conducted among horses.     

Comparison of two modern vaccines and previous influenza infection against challenge with an equine influenza virus from the Australian 2007 outbreak

During 2007, large outbreaks of equine influenza (EI) caused by Florida sublineage Clade 1 viruses affected horse populations in Japan and Australia. The likely protection that would be provided by two modern vaccines commercially available in the European Union (an ISCOM-based and a canarypox-based vaccine) at the time of the outbreaks was determined. Vaccinated ponies were challenged with a representative outbreak isolate (A/eq/Sydney/2888-8/07) and levels of protection were compared. A group of ponies infected 18 months previously with a phylogenetically-related isolate from 2003 (A/eq/South Africa/4/03) was also challenged with the 2007 outbreak virus. After experimental infection with A/eq/Sydney/2888-8/07, unvaccinated control ponies all showed clinical signs of infection together with virus shedding. Protection achieved by both vaccination or long-term immunity induced by previous exposure to equine influenza virus (EIV) was characterised by minor signs of disease and reduced virus shedding when compared with unvaccinated control ponies. The three different methods of virus titration in embryonated hens’ eggs, EIV NP-ELISA and quantitative RT-PCR were used to monitor EIV shedding and results were compared. Though the majority of previously infected ponies had low antibody levels at the time of challenge, they demonstrated good clinical protection and limited virus shedding. In summary, we demonstrate that vaccination with current EIV vaccines would partially protect against infection with A/eq/Sydney/2888-8/07-like strains and would help to limit the spread of disease in our vaccinated horse population.     

Facing the threat of equine parasitic disease

Horses worldwide are exposed to a complex mixture of intestinal parasitic helminths. When burdens are high, these parasites can seriously compromise health and welfare. Some helminth species have an extremely high prevalence and are difficult to control, not least because there is a limited understanding of their most basic biology. Furthermore, levels of resistance to some of the commonly used anthelmintics are widespread and increasing. The cyathostomins are the most common nematode species affecting equids worldwide. Within this group of parasites are more than 50 different species. Until recent research activities, little was known about the contribution that individual species make to clinical disease, parasite epidemiology and anthelmintic resistance. This review describes some of the recent research advances in the understanding of cyathostomins in these areas. As part of the research effort, molecular tools were developed to facilitate identification of the non-parasitic stages of cyathostomins. These tools have proved invaluable in the investigation of the relative contributions that individual species make to the pathology and epidemiology of mixed infections. At the more applied level, research has also progressed in the development of a diagnostic test that will allow numbers of cyathostomin encysted larvae to be estimated. This test utilises cyathostomin-specific serum antibody responses as markers of infection. As anthelmintic resistance will be the major constraint on parasite control in future, researchers are actively investigating mechanisms of drug resistance and how to improve the detection of resistance in the field. Recent developments in these areas are also outlined.     

Management and environmental factors involved in equine influenza outbreaks in Ireland 2007-2010

Reasons for performing study: Outbreaks of equine influenza (EI) in endemic populations continue to cause economic loss despite widespread vaccination. Hypothesis: To identify the key management and environmental factors that determine the risk of horses contracting EI in an endemic country and to identify control strategies. Methods: Real time‐polymerase chain reaction (RT‐PCR), virus isolation and haemagglutination inhibition were carried out on nasopharyngeal swabs and clotted blood samples collected from horses and ponies showing signs of respiratory disease. On premises where a diagnosis of EI was confirmed, the attending veterinary surgeon was asked to participate in an epidemiological investigation. Results: Between June 2007 and January 2010, EI outbreaks were diagnosed on 28 premises located in 13 of the 32 counties of Ireland. Veterinary advice was sought on average more than 5 days after the first clinical signs were observed. The majority of diagnoses were made by RT‐PCR. Data from 404 horses on 16 premises were used in the epidemiological analysis. In 15 premises, EI was identified following movement of horses. Housing type, teaser stallions or fomites/personnel contributed to virus spread. Vaccination status, number of years vaccination, time since last vaccination and age influenced disease expression. Isolation and vaccination were effective control measures on the premises where they were implemented. Conclusions: Preventative measures include: isolation, clinical monitoring, serological testing and vaccination of new arrivals, booster vaccination of horses at 6 monthly intervals, maintenance of effective boundaries between equine premises and avoidance of stabling in single air spaces. Control measures include: prompt isolation of suspected cases, rapid diagnosis by RT‐PCR, booster vaccination of cohorts and implementation of biosecurity measures to avoid transmission by fomites and personnel. Potential relevance: Implementation of these preventative and control measures should reduce the economic losses associated with outbreaks of EI.     

Detection of clade 2 equine influenza virus in an adult horse recently imported to the USA

A 4‐year‐old Warmblood mare presented to the William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California at Davis with bilateral mucoid nasal discharge and pyrexia. The mare had recently been imported from Germany, arriving at a quarantine holding facility 72 h prior to presentation. Based on clinical presentation and culture results of tracheal fluid, the mare was diagnosed with bacterial bronchopneumonia secondary to equine influenza. The equine influenza virus (EIV) identified in the imported mare displayed 99.1% nucleotide homology of the HA1 gene to the prototype Florida sublineage clade 2 isolate A/equine/Richmond/1/2007 (H3N8). This case illustrates the risk of introducing a clade 2 EIV in North America.     

马流感病毒血凝素基因甲病毒复制子重组表达质粒的构建及其免疫效力评价

为评价马流感病毒(EIV)HA基因核酸免疫效果,本研究以甲病毒复制子载体pSFV1CS分别构建了表达EIV H3N8亚型的美洲型和欧洲型HA基因的重组真核表达质粒。并将其转染293T细胞,经间接免疫荧光鉴定表明HA基因获得表达;以重组质粒免疫的BALB/c鼠能够检测到特异性抗体产生,而且HI抗体水平持续升高,同时小鼠体内IFN-γ、IL-4分泌水平也有所升高。攻毒后小鼠表现轻度临床症状,但病毒分离和RT-PCR均未检测到病毒。上述结果表明,该重组质粒pSFV1CS-EIV-HA具有良好的免疫原性并且可以诱导免疫动物产生较高免疫应答的能力。