Role of feline ANP32 proteins in regulating polymerase activity of influenza A virus

Recently,increasing natural infection cases and experimental animal challenge studies demonstrated domestic cats are susceptible to multiple subtypes influenza A virus(IAV)infections.Notably,some subtype IAV strains could circulate in domestic cats after cross-species transmission and even infected humans,posing a threat to public health.Host factors related to viral polymerase activity could determine host range of IAV and acidic nuclear phosphoprotein 32(ANP32)is the most important one among them.However,role of cat-derived ANP32 on viral polymerase activity and host range of IAV is still unknown.In the present study,a total of 10 feline ANP32(feANP32)splice variants(including 5 feANP32A,3 feANP32B,and 2 feANP32E)were obtained from domestic cats by RT-PCR.Sequence alignment results demonstrated amino acid deletions and/or insertions occurred among feANP32 variants,but all feANP32 proteins were primarily localized to cell nucleus.Minigenome replication systems for several representative IAV strains were established and the support ability of feANP32 on IAV polymerase activity was estimated.The results indicated that most feANP32A and feANP32B splice variants were able to support all the tested IAV strains,though the support activity of a single feANP32 protein on polymerase activity varied among different IAV strains.In addition,the role of feANP32 in supporting H3N2 canine influenza virus was determined by investigating viral replication in vitro.Collectively,our study systematically investigated the support activity of feANP32 on IAV,providing a clue for further exploring the mechanism of susceptibility of cats to IAV.

Isolation of a feline-derived feline panleukopenia virus with an A300P substitution in the VP2 protein and confrmation of its pathogenicity in dogs

Feline panleukopenia virus(FPV)is a single-stranded DNA virus that can infect cats and cause feline panleukopenia,which is a highly contagious and fatal disease in felines.The sequence of FPV is highly variable,and mutations in the amino acids of its capsid protein play crucial roles in altering viral virulence,immunogenicity,host selection,and other abilities.In this study,the epidemiology of FPV was studied using 746 gastrointestinal swab samples derived from cats that presented gastrointestinal symptoms specifcally,diarrhea or vomiting during the period spanning from 2018 to 2022.The overall prevalence of FPV-positive patients among these samples was determined to be 45.4%.Capsid(virion)protein 2(VP2)gene of each FPV-positive sample was sequenced and amplifed,yielding 65 VP2 sequences.Among them,six VP2 gene sequences were detected in the majority of the samples test positive for FPV,and these positive samples originated from a diverse range of geographical locations.These isolates were named FPV-6,FPV-10,FPV-15,FPV-251,FPV-271 and FPV-S2.Additionally,the substitution of Ala300Pro(A300P)in VP2 was detected for the frst time in feline-derived FPV(FPV-251).FPV-251 isolate,with this substitution in VP2 protein,exhibited stable proliferative capacity in Madin-Darby canine kidney(MDCK)cells and A72 cells.FPV-271 was selected as the FPV control isolate due to its single amino acid diference from VP2 protein of FPV-251 at position 300(FPV-271 has alanine,while FPV-251 has proline).After oral infection,both FPV-251 and FPV-271 isolates caused feline panleukopenia,which is characterized by clinical signs of enterocolitis.However,FPV-251 can infect dogs through the oral route and cause gastrointestinal(GI)symptoms with lesions in the intestine and mesenteric lymph nodes(MLNs)of infected dogs.This is the frst report on the presence of an A300P substitution in VP2 protein of feline-derived FPV.Additionally,FPV isolate with a substitution of A300P at VP2 protein demonstrated efcient replication capabilities in canine cell lines and the ability to infect dogs.

Nitric oxide activation of a potassium channel (BK_(Ca)) in feline lower esophageal sphincter

AIM:To assess the effect of nitric oxide (NO) on the large conductance potassium channel (BKCa) in isolated circular (CM) and sling (SM) muscle cells and muscle strips from the cat lower esophageal sphincter (LES) to determine its regulation of resting tone and relaxation.METHODS:Freshly enzymatically-digested and isolated circular smooth muscle cells were prepared from each LES region.To study outward K + currents,the perforated patch clamp technique was employed.To assess LES resting tone and relaxation,muscle strips were mounted in perfused organ baths.RESULTS:(1) Electrophysiological recordings from isolated cells:(a) CM was more depolarized than SM (-39.7 ± 0.8mV vs-48.1 ± 1.6 mV,P < 0.001),and maximal outward current was similar (27.1 ± 1.5 pA/pF vs 25.7 ± 2.0 pA/pF,P > 0.05);(b) The NO donor sodium nitroprusside (SNP) increased outward currents only in CM (25.9 ± 1.9 to 46.7 ± 4.2 pA/pF,P < 0.001) but not SM (23.2 ± 3.1 to 27.0 ± 3.4 pA/pF,P > 0.05);(c) SNP added in the presence of the BK Ca antagonist iberiotoxin (IbTX) produced no increase in the outward current in CM (17.0 ± 2.8 vs 13.7 ± 2.2,P > 0.05);and (d) L-NNA caused a small insignificant inhibition of outward K + currents in both muscles;and (2) Muscle strip studies:(a) Blockade of the nerves with tetrodotoxin (TTX),or BK Ca with IbTX had no significant effect on resting tone of either muscle;and (b) SNP reduced tone in both muscles,and was unaffected by the presence of TTX or IbTX.CONCLUSION:Exogenous NO activates BK Ca only in CM of the cat.However,as opposed to other species,exogenous NO-induced relaxation is predominantly by a non-BK Ca mechanism,and endogenous NO has minimal effect on resting tone.

Isolation and phylogenetic analysis of feline calicivirus strains from various region of China

Feline calicivirus(FCV)is an important feline pathogen mainly causing upper respiratory tract disease,conjunctivitis,and stomatitis,and it is classifed into genotype I and genotype II.To investigate the prevalence and molecular characteristics of FCV,this study collected 337 cat swab samples from animal hospitals in diferent regions of China from 2019 to 2021.The positive detection rate of FCV was 29.9%(101/337)by RT-PCR.Statistical analysis showed that FCV prevalence was signifcantly associated with living environment(p=0.0004),age(p=0.031)and clinical symptoms(p=0.00),but not with sex(p=0.092)and breed(p=0.171).The 26 strains of FCV were isolated using F81 cells.Phylogenetic analysis showed that 10 isolates belonged to genotype I,and 16 isolates belonged to genotype II.These 26 isolates were highly genetically diverse,of which HB7 isolate had three same virulence-related amino acid loci with VSD strains.Potential loci distinguishing diferent genotypes were identifed from 26 isolates,suggesting the genetic relationship between diferent genotypes.In addition,selection pressure analysis based on capsid protein of 26 isolates revealed that the protein is under diversifying selection.This study reveals the genetic diversity of FCV and provides a reference for the screening of vaccine candidate strains and the development of vaccines with better cross-protection efects.

Expedited Management of Canine and Feline Vomiting and Diarrhea. Observational Study in 3952 Dogs and 2248 Cats Using Sucralfate-Like Potency-Enhanced Polyanionic Phyto-Saccharide—Elm Mucilage

A potency-enhanced polyanionic phyto-saccharide of elm mucilage (PEPPS) was prescribed by 197 small animal veterinarians in an open-labeled field trial. Clients provided informed consent to veterinarians to prescribe PEPPS to 3952 dogs and 2248 cats. A 2 day/4 dose response rate, determined by veterinarians’ consensus, provided clinical threshold for a significant clinical outcome. Data was collected through phone interviews conducted over a period of 3.5 years from June 2003 through December 2006. 82% of 1928 vomiting dogs and 77% of 1064 vomiting cats responded to PEPPS within 2 days or four doses. 93% of 2024 dogs and 79% of 1184 cats with diarrhea responded to PEPPS within 2 days or four doses. PEPPS appears useful for managing vomiting and diarrhea in dogs and cats. However, a randomized blinded placebo controlled trial is needed to quantify true clinical efficacy.

Case Report on Feline Polycythemia Vera

Polycythemia vera has been reported as a known condition in cats as early as 1966. This condition manifests as an increased mass in red blood cells and elevated hematocrit and is defined as an idiopathic chronic myeloproliferative disorder. The patient described in this paper presented with hyperemic gums and pinna and an acute onset of progressive ataxia and lethargy. Several possible underlying primary conditions such as cardiac disease and renal malignancy were excluded by running basic blood work and radiographic imaging. Initial blood work revealed a significantly elevated packed cell volume (88%). After diagnosis, treatment with phlebotomy and chemotherapy lead to a reduction in hematocrit and elimination of neurologic signs. This case study represents the diagnosis and successful management of this disease in a private practice setting. Polycythemia vera is relatively uncommon in dogs and cats, but should still be considered in cases of neurologic disorders, especially with the presence of bright red ears, paws, or gums.

Generalizations of the Feline and Texas Chainsaw Josephus Problems

We define and study the Extended Feline Josephus Game, a game in which n players, each with &#8467;lives, stand in a circle. The game proceeds by alternating between hitting k consecutive players—each of whom will consequently lose a life—and skipping s consecutive players. This cycle continues until every player except one loses all of their lives. Given the nonnegative integer parameters n, k, s and &#8467;, the goal of the game is to identify the surviving player. In this paper, we show how the defining parameters n, k, s, and &#8467;affect the survivor of games with specific constraints on those parameters and our main results provide new closed formulas to determine the survivor of these Extended Feline Josephus Games. Moreover, for cases where these formulas do not apply, we provide recursive formulas for reducing the initial game to other games with smaller parameter values. For the interested reader, we present a variety of directions for future work in this area, including an extension which considers players lying on a general graph, rather than on a circle.

Comparative evaluation of acute phase proteins by C-reactive protein(CRP)and serum amyloid A(SAA)in nonhuman primates and feline carnivores

The feasibility of a commercially available assay for C-reactive protein(CRP,CRP for humans:hCRP,and CRP for dogs:vCRP)and a trial reagent of serum amyloid A(SAA,vSAA for animals)were applied to the measurement of acute phase proteins in zoo animals,particularly in nonhuman primates and feline carnivores was evaluate.Results showed that hCRP and vSAA methods were applicable to measure CRP and SAA in Haplorhini.There was a highly signifcant correlation between both parameters with remarkably high correlation coefcient.A higher proportion of Bonnet macaques in Haplorhini,and the linear regression with good correlation between hCRP and vSAA levels were observed.Reference values in healthy Bonnet macaques were hCRP(46.86±30.97 nmol/L)and vSAA(9.06±1.95μg/mL).Although Ring-tailed lemur,which belonging to Strepsirrhini,showed low vSAA concentrations(reference values:1.08±0.47μg/mL),vSAA in patients was apparently elevated.The vCRP and vSAA methods were applicable to measurements of CRP and SAA in feline carnivores for highly signifcant correlation between both parameters.Theses two methods were also been deteded in lions,tigers and cheetahs.vSAA assays can be applied to measure SAA levels in other carnivores and herbivores.In conclusion,vSAA systems have potential utility as diagnostic tools for health screening and prediction in zoo animals.

Diagnosis,Treatment and Experience of A Case of Feline Lower Urinary Tract Syndrome

In February 2018,a 2-year-old American shorthair was treated conservatively for cystitis caused by crystalluria.However,as long as drug withdrawal was proceeding,the condition would be repeated,and the condition worsened since August.In order to diagnose and treat the sick cat,clinical examination,laboratory examination,X-ray,B-type ultrasound and other methods were used for diagnosis,and treatment was conducted according to the diagnosis results.The results showed that the cat was caused by ammoniomagnesium phosphate crystals blocking urethra,complicated with postrenal azotaemia and hyperkalemia.The relapse continued after conservative treatment,and the cat finally recovered by modifying urethra surgically.The results showed that the deficiency of drinking water,the change of urine pH,and high dietary magnesium and fiber content could promote the occurrence of the disease.For the problem of urethral obstruction that could not be solved by conservative treatment,operation was done to modify urethral stricture.

Feline Hypertrophic Cardiomyopathy Associated with the p.A31P Mutation in cMyBP-C Is Caused by Production of Mutated cMyBP-C with Reduced Binding to Actin

Hypertrophic cardiomyopathy (HCM) is a myocardial disorder, with complications including heart failure, thromboemboli and sudden death. Human and feline HCM (fHCM) are clinically comparable, thus fHCM may serve as a spontaneous animal model. fHCM in Maine Coon (MC) cats is associated with the p.A31P mutation in the cMyBP-C protein. The mutation is located in the cMyBP-C C0-domain which is known to interact with actin. The presence and levels of the wild type and mutated protein in heart tissue from mutant and wild type MC cats were examined by SDS-PAGE and mass spectrometry (MS). Quantitative yeast-2-hybrid (Y2H) protein-protein interaction analysis was used to assess the effect of the mutation on C0C1/actin interaction. The NMR-based structure of the C0 domain was used to calculate the energetic consequence of replacing alanine with a proline residue. In the homozygous MC cat, the mutated cMyBP-C protein was present, and cMyBPC-C levels were not reduced compared to that of the wild type cat. However, the interaction of actin with mutant cMyBP-C C0C1 was reduced compared to that of wild type. This may be because the substitution of the alanine with proline in position 31 was energetically highly unfavorable and resulted in only one hydrogen bond within the anti-parallel beta-strand compared to two hydrogen-bonds for alanine, possibly destabilizing the structure of the actin-interacting domain. The p.A31P mutation is present in cardiac tissue and the most likely pathogenic mechanism is interference with contractility by reducing binding of the C0C1 domain of cMyBP-C to actin.

猫泛白细胞减少症病毒A91S变异株对猫的致病性及基因组特征研究

猫泛白细胞减少症病毒(feline panleukopenia virus, FPV)是一种对猫危害严重的病原。近年来,一种VP2 91位氨基酸残基由A突变为S的FPV变异株(FPV A91S变异株)已经在国内广泛流行,但目前还未见该变异株对猫致病性的报道,本试验旨在探究FPV A91S变异株对猫的感染特性及其分子特征。利用F81细胞分离FPV A91S变异株,并研究其血凝特性、对猫的致病性及其基因组特征。成功分离到一株FPV A91S变异株,纯化后病毒滴度为10~(4.6 )TCID_(50)·mL^(-1);该毒株能在pH 6.0~6.5、4和37℃条件下有效凝集猪红细胞;分离株经口服成功感染幼猫,引起呕吐、腹泻、白细胞急剧降低、眼睑脓性分泌物等症状,并在5 d内导致猫死亡;大体和组织病理变化发现严重的肠道和肺出血。获得该毒株近乎全长的基因组序列,其VP2蛋白的关键位点氨基酸符合典型FPV特征。除了VP2 A91S的突变外,其NS1蛋白也有3个独特的氨基酸突变(D23N、I443V和H596Q),这些特征导致FPV A91S毒株在进化树中单独聚为一支,具有独特的遗传进化趋势。本研究首次探究了FPV A91S变异株的血凝性和对猫的致病性,为进一步了解FPV的生物学特性和遗传变异提供参考。

52例猫坏死性角膜炎病例报告

猫坏死性角膜炎是一种常见的猫角膜疾病,我国针对该病的研究较少,治疗方案不一。本试验收集2019年1月─2021年1月在中国农业大学动物医院就诊的52例猫坏死性角膜炎病例(共56只患眼),对病例统计分析,总结该病特征性的临床症状,讨论不同治疗方案的优缺点。结果显示,猫坏死性角膜炎高发品种为异国短毛猫(22/52,42.3%),高发年龄段为<7岁(50/52,96.2%),慢性角膜刺激是该病的常见病因。在52例患猫病例中,34例(共38只患眼)进行角膜切除术治疗,其中22只患眼同时进行了第三眼睑遮盖术,另外16只患眼同时进行了结膜瓣遮盖术。2例患猫病例术后出现坏死性角膜炎复发,均为年轻斯芬克斯猫。结果表明,角膜切除术是治疗猫坏死性角膜炎的首选治疗方案,坏死角膜的残留可能造成术后复发。

1例猫眼线虫伴有双侧第三眼睑腺脱出病例的诊治报告

文章报告了一例罕见的猫眼线虫病伴有双侧第三眼睑腺脱出的病例。一只3岁的英国短毛猫眼部红肿、畏光流泪等症状并伴有双侧第三眼睑腺脱出,之后进行全面的眼部检查和实验室检查,采用清除眼线虫和第三眼睑腺包埋手术进行治疗,患猫的眼睑消肿,分泌物减少。术后12 d,第三眼睑腺恢复到正常位置,眼部周围干净,预后良好。该病例提示猫眼线虫病可能在特定条件下感染,并罕见伴有第三眼睑腺脱出。治疗时应首先清除眼线虫,之后采用“口袋”技术包埋第三眼睑腺,取得了满意的矫正效果。在预防中,应注意避免苍蝇媒介,以降低感染的风险。

敲除CRFK细胞氨基肽酶N对猫传染性腹膜炎病毒复制影响的研究

猫氨基肽酶N(fAPN)参与猫传染性腹膜炎病毒(FIPV)的感染过程,为研究f APN对FIPV复制的影响,本研究针对f APN第14外显子设计了1对sg RNA,将sg RNA退火后克隆至p X458质粒中,构建同时含有Cas9蛋白和sg RNA的重组质粒。重组质粒经PCR及测序鉴定正确后,瞬时转染猫肾细胞(CRFK)中,24 h后通过流式细胞仪分选带有绿色荧光的单克隆细胞。单克隆细胞经稳定传代培养后,细胞中的绿色荧光消失,对细胞进行PCR和测序,结果显示:3株单克隆细胞在f APN第14外显子有1个碱基的插入,造成移码突变,导致f APN不能正常表达,表明敲除f APN蛋白的CRFK细胞系正确构建,命名为KO-APN14。将FIPV分别感染CRFK细胞及培养20代的KO-APN14细胞,48 h后通过间接免疫荧光试验(IFA)检测FIPV N蛋白的表达;将FIPV分别感染CRFK细胞及KO-APN14细胞,在感染4 h、12 h、24 h、36 h时采用RT-q PCR分别检测FIPV N基因、视黄酸(维甲酸)诱导基因I(RIG-I)、黑色素瘤分化相关基因5(MDA5)、Toll样受体3(TLR3)、干扰素β(IFN-β)、肿瘤坏死因子α(TNF-α)、白细胞介素-6(IL-6)、白细胞介素-10(IL-10)的转录水平。IFA结果显示:感染FIPV的CRFK细胞出现绿色荧光,未感染FIPV的CRFK细胞、未感染FIPV的KO-APN14细胞及感染FIPV的KO-APN14细胞均无绿色荧光;RT-q PCR检测FIPV感染各细胞后病毒N基因的转录水平,结果显示:与感染FIPV的CRFK细胞相比,感染FIPV的KO-APN14细胞能够极显著抑制FIPV N基因的转录(P<0.0001);RT-q PCR检测FIPV感染各细胞后上述各细胞因子的转录水平,结果显示:与感染FIPV的CRFK细胞相比,感染FIPV的KO-APN14细胞能够抑制RIG-I、MDA5、TLR3、IFN-β、IL-6、IL-10、TNF-α及f APN的转录。综上所述,f APN是FIPV在侵入细胞及病毒复制过程中发挥重要作用,并在FIPV引起的炎症反应过程中起关键作用。本研究为f APN在免疫炎症反应中作用的研究提供科学依据,并为培育基因编辑抗病育种猫奠定实验基础。

猫冠状病毒荧光定量PCR检测方法的建立

猫冠状病毒(FCoV)在全球猫种群中广泛流行,隐形感染的猫导致病毒在猫群中持续传播。提高样本检测率、早预防、早治疗可减少种群中病毒流行率。为建立可以灵敏、准确检测FCoV的Taq Man荧光定量PCR检测方法,根据GenBank公布的FCoV基因片段N保守区域设计了1对特异性引物和1条探针,通过优化反应体系,建立了FCoV Taq Man荧光定量PCR检测方法,对75份临床样品进行检测。结果表明,该方法在1.49×10^(11)~1.49×10^(2) copies/μL之间具有良好的线性关系,特异性强,敏感性高,对FCoV质粒标准品最低检测下限为1.49×10^(0) copies/μL,而普通PCR对FCoV质粒标准品最低检测下限为1.49×10^(5) copies/μL;重复性好,组内变异系数和组间变异系数均小于3%;75份临床样品,阳性率为37.33%。研究建立的FCoV检测方法扩增效率高、特异性强、敏感性好、稳定性高,且实用性好,可以用于FCoV的快速检测,可为流行病学调查提供有效的技术手段。

10例猫特发性膀胱炎临床诊断和治疗的回顾性分析

为了分析猫特发性膀胱炎(FIC)临床现有治疗方法的效果,了解其治疗和转归情况,以提高临床兽医对本病的认识,本调查跟踪追访2017年10月—2019年3月在中国农业大学教学动物医院确诊为FIC的10例患猫病例,对其基本信息、临床症状、影像学检查、实验室检查、治疗和转归情况进行总结和分析。结果显示,10例病例患猫均为雄性,以商品化干粮为主食,在室内饲养,一半患猫体重超重,所有患猫在发病前均经历过可知的压力事件;患猫临床表现为泌尿道和消化道症状;影像学检查结果显示,患猫泌尿道均未见结石征象;实验室检查结果显示,患猫存在不同程度的白细胞升高、中性粒细胞升高、氮质血症、高血磷和高血钾等;尿液细菌培养结果均为阴性;镇痛镇静解痉挛药物、导尿和增加饮水量可有效缓解病情,修复膀胱黏膜药物的治疗效果不理想;10例病例患猫均使用镇痛镇静解痉挛药物治疗,7例临床症状缓解(有效率70%);2例实施尿道造口术治疗的患猫中,1例临床症状缓解,1例出现血尿和膀胱结石。结果表明,各种应激因素均可诱发FIC,急性发病期可通过镇痛镇静解痉挛和导尿的方式有效缓解病情、治疗疾病;日常管理中增加饮水量可有效预防FIC。复发性FIC或者无法用保守疗法治疗的病例,可以考虑进行尿道造口术,但是需要进行严格的术后管理以防止产生并发症。

猫传染性腹膜炎病毒N蛋白表达及其多克隆抗体制备

本研究旨在体外原核表达猫传染性腹膜炎病毒(feline infectious peritonitis virus,FIPV)SH2021株核衣壳蛋白(nucleocapsid,N),制备兔源多克隆抗体。根据FIPV SH2021株N基因序列设计引物,构建pCold-I-N重组表达质粒。随后,将重组质粒转化至表达感受态细胞BL21(DE3),在终浓度为1.0 mmol·L^(-1)的IPTG和16℃的诱导条件下进行表达。最后,利用His层析柱进行纯化,纯化后的重组蛋白免疫新西兰大白兔制备多克隆抗体。结果表明,纯化获得重组N蛋白大小约为45 ku,制备的N蛋白兔多克隆抗体效价可达1∶512000,该抗体对N蛋白具有良好的反应原性。本研究成功所制备了FIPV N蛋白兔多克隆抗体,该抗体具有良好的反应原性和特异性,为FIPV抗原抗体检测以及研究N蛋白生物学功能研究提供重要工具。

猫杯状病毒的分离纯化及遗传进化特征分析

猫杯状病毒(FCV)作为导致猫上呼吸道感染的重要病原,具有高度传染性,严重危害猫科动物健康。为了解山西省FCV分离株变异水平及遗传发育特征,使用猫肾细胞(CRFK)分离、纯化山西省FCV分离株,用透射电镜观察病毒形态,测定病毒半数感染量(TCID_(50))和生长曲线,基于结构蛋白VP1分析猫杯状病毒基因、氨基酸变异水平与遗传发育特征。结果显示,试验纯化得3株山西省FCV分离株(SX-2021-1、SX-2021-2和SX-2021-3),病毒大小约为40 nm,TCID_(50)为10^(-8.43)/mL,FCV感染CRFK细胞的6~72 h中,在24 h时病毒滴度达到最高(SX-2021-3)。SX-2021-1与SX-2021-2株的VP1基因同源性为99.8%,SX-2021-3株VP1基因呈现较高的变异性,与其他两株的同源性约为77%。FCV山西分离株与已公布FCV毒株同源性为70.7%~83.9%,其中SX-2021-1、SX-2021-2与我国黑龙江分离株(HRB-SS)同源性最高(83.9%),SX-2021-3与我国上海分离株(SH1)同源性最高(80.5%)。FCV山西分离株VP1蛋白在E区5′高变区和3′高变区均存在多个氨基酸位点突变,其中SX-2021-3株与其他两株的VP1蛋白氨基酸差异性明显。遗传进化分析结果显示,FCV山西分离株与疫苗株和VSD毒株亲缘关系均较远,SX-2021-1、SX-2021-2与我国黑龙江地区分离株(HRB-SS、WZ-1和XH)亲缘关系较近;SX-2021-3与上海毒株(SH1)处于同一分支。综上,本研究阐明了山西省FCV分离株变异水平及遗传发育特征,为FCV病原及疫苗研究提供了重要依据。

基因Ⅱ型猫杯状病毒XA20-2023株的分离鉴定及基因组序列分析

为了解猫杯状病毒(FCV)的生物学特性及遗传规律,本研究对从陕西西安地区采集的17份疑似FCV感染的口鼻咽样品经PCR检测,并经PCR扩增FCV阳性样品的VP1基因并测序。采用SnapGene软件分析GenBank中国内外23株FCV参考株与所测VP1的氨基酸序列,结果显示,17份拭子样品中有6份呈FCV阳性,阳性率为35.3%。氨基酸序列分析结果显示,所测VP1序列中有一条与GⅡ型FCV VP1氨基酸序列存在3处相同的变异,分别为N^(377)K、A^(539)V、G^(557)S,其余5条VP1氨基酸序列的变异与GI型FCV的VP1一致。表明所测VP1基因序列对应的FCV属于GⅡ型。将该FCV阳性样品接种CRFK细胞进行病毒的分离与传代,并在传代过程中观察细胞的CPE。将传至5代的病毒分别采用PCR与间接免疫荧光试验(IFA)鉴定,结果显示连续传5代后,每代CRFK细胞均产生稳定且典型的CPE,并能观察到FCV的特异性绿色荧光,表明分离到一株GⅡ型FCV并命名为XA20-2023株。经PCR分段扩增第5代分离病毒的全基因组序列,测序拼接后显示XA20-2023株全长7 687 bp。采用MegAlign软件分析该株病毒与GenBank中10株FCV的全基因组、非结构蛋白、VP1及VP2编码基因序列的同源性。采用MEGA 11软件中的NJ法构建XA20-2023株与GenBank中85株FCV参考株全基因组序列的系统发育树。同源性分析结果显示,XA20-2023株与GenBank中10株FCV全基因组序列的同源性为76.4%~84.2%,与GⅡ型FCV SH株全基因组序列的同源性最高为84.2%,与GI型疫苗株F9、F4及FCV 255株全基因组序列的同源性分别为76.4%、77%及77.1%。非结构蛋白编码基因序列的同源性差异最大的是NS2(74.6%~94.2%),差异最小的是NS6(77.3%~82.9%)。VP1及VP2编码基因序列的同源性分别为73.7%~83.8%及76.0%~87.5%。进化树结果显示XA20-2023株与GⅡ型分离株处于同一分支,与GI型疫苗株F9和F4的遗传距离较远。上述结果进一步表明,XA20-2023株为GⅡ型FCV,与FCV代表株尤其是GI型疫苗株的同源性较低,且其变异程度较高。本研究丰富了西安地区流行的GⅡ型FCV基因库,并为后续揭示国内GⅡ型FCV的流行状况、遗传变异及其所致疫病的防制具有重要意义。

猫上呼吸道疾病的病原、诊断与防治

猫上呼吸道疾病(feline upper respiratory tract disease, FURTD)是一种在猫中广泛传播的以上呼吸道、口腔和眼部症状为主的疾病。引起FURTD的病原多样,除常见的猫杯状病毒(feline calicivirus, FCV)、猫疱疹病毒Ⅰ型(feline herpesvirus type 1,FHV-1)、猫衣原体(Chlamydia felis,C.felis)、猫支原体(Mycoplasma felis,M.felis)、支气管败血波氏杆菌(Bordetella bronchiseptica,Bb)外,临床中还有许多其他的病原偶见感染。临床中常出现由多种病原体混合感染的情况,并且病原的不断进化容易造成致病性的增强和组织嗜性的改变,这种病因的复杂性往往使得FURTD的防治较为困难。同时,由于许多病原感染引起猫的症状相似,仅凭临床症状无法准确判断出病因,准确认识不同病原的特性、掌握不同的病原检测方法对FURTD的病因快速诊断和提出高效的治疗方案至关重要。目前,不同病原引起的FURTD病例常被报道,而针对FURTD的诊断方法、治疗以及疫苗研制都尚未成熟,本文将对该疾病的常见和新发病原、诊断方法、治疗手段和防控措施进行系统地阐述,旨在为FURTD的防治工作提供更多的思路。