2.2.1 豬圓環病毒2型
Porcine circovirus type 2
豬圓環病毒2型(PCV2)是一種無包膜小DNA病毒，屬於圓環病毒科、圓環病毒屬。豬同時感染PCV2並出現其他相關疾病，一般統稱為PCV2相關疾病[63]。感染PCV2病毒後，母豬會出現繁殖障礙，如晚期流產和死胎，但在實際生產中並不常見。感染PCV2的成年公豬通常不會出現臨床症狀及病變[24,26]。自然感染和實驗感染的公豬精液中，已檢測到該病毒[24]。實驗感染中，分別在感染後第2天和第5天，於血清和精液中檢測到PCV2 DNA [24,26]。檢測精液相關病毒之前，先進行PCV2病毒血症檢測，但即使未出現病毒血症，精液也可能散毒。實驗感染公豬後，一些研究發現公豬精液間斷散毒[24,25]，而其他研究則發現精液持續散毒[26]。McIntosh等人[27]表明，自然感染的公豬在長達27周的時間內，精液偶爾散毒。這些數據表明，精液可能是PCV2的重要載體。病毒常汙染精漿，但是在精漿和精子中均能檢測到PCV2 [23,33]。精子很少發生形態、活力和濃度方面的變化[26]。能繁母豬感染PCV2後也很少表現臨床症狀[64]。
Porcine circovirus type 2 (PCV2) is a small nonenveloped DNA virus that belongs to the family circoviridae, genus Circovirus. Infections with PCV2 in pigs are associated with different disease conditions commonly referred to as PCV2-associated disease [63]. Reproductive problems in sows such as late-term abortions and stillbirths have also been described but are considered to be rare under field conditions. Mature boars infected with PCV2 generally lack clinical signs and lesions [24,26]. The virus has been detected in semen of naturally and experimentally infected boars [24]. On experimental infection, PCV2 DNA has been detected in serum and semen at 2 and 5 days after infection, respectively [24,26]. Detection of PCV2 viremia commonly precedes the detection of semen-associated virus, but semen shedding may occur in the absence of viremia. After experimental infection of boars, some studies found intermittent shedding in semen [24,25], whereas other studies observed continuous shedding of the virus [26]. McIntosh et al. [27] showed that naturally infected boars shed the virus sporadically in semen for up to 27 weeks. These data suggest that semen may be a significant vehicle for PCV2. The seminal plasma is usually contaminated, but PCV2 is not only detected in the non–sperm cell fraction but also in the sperm one [23,33]. Changes in semen morphology, motility, and concentration are not commonly found [26]. Clinical signs on PCV2 infection in breeding sows are rare [64].
在精液中加入PCV2，對未免疫過的母豬進行實驗感染，則會出現繁殖障礙、胎兒感染[41]。但是，自然感染情況下，精液內PCV2病毒數量是否足以感染母豬或其胎兒，尚不明確。該病毒能夠在無透明帶的胚胎中複製，從而導致胚胎死亡[65,66]。在PCV2相關疾病中，不常見到分娩推遲或假妊娠。受PCV2影響的窩，仔豬死亡數量可能會增加[67]。
Naïve sows inseminated with semen experimentally spiked with PCV2 exhibited reproductive failure, and their fetuses became infected [41]. However, it is not known if the quantity of PCV2 naturally shed in semen is sufficient to infect sows or their fetuses. The virus is able to replicate in zona pellucida–free embryos, leading to embryonic death [65,66]. Delayed farrowing or pseudopregnancy is less frequently observed with PCV2-associated reproductive failure. An increased number of nonviable piglets may be present in PCV2-affected litters [67].
2.2.2. 豬巨細胞病毒
Porcine cytomegalovirus
豬巨細胞病毒或豬皰疹病毒2型是一種DNA病毒，屬於皰疹病毒科，皰疹病毒亞科，但不屬於任何屬。成年豬只感染豬巨細胞病毒，通常為亞臨床感染。公豬感染後，在睪丸和附睪中能檢測到病毒[28]。射出的精液是否散毒，尚未明確。
Porcine cytomegalovirus or suid herpesvirus type 2 is a DNA virus that belongs to the subfamily betaherpesvirinae of the family herpesviridae but is not assigned to any genus. Infection with porcine cytomegalovirus is usually subclinical in adults. After infection in boars, the virus was detected in the testis and epididymis [28]. Shedding of virus in ejaculated semen has not been determined.
2.2.3. 豬細小病毒豬細小病毒(PPV)是一種無包膜小DNA病毒，屬於細小病毒科，細小病毒屬。該病毒在豬群中很常見。PPV主要的傳播途徑是口鼻傳播和胎盤傳播。已多次從自然感染的公豬精液中分離出該病毒。急性感染期，公豬精液可散毒[34]；雖尚未證實之後階段是否繼續散毒，但是由於子宮早期感染，可能導致PPV免疫耐受個體產生[68]。也可能是含有病毒的糞便微粒，或雄性生殖器官，導致精液汙染[45,46]。公豬群中，感染後通常無臨床症狀。實驗感染公豬，其繁殖力或性慾[46]，精子數量、精液量、精子活力或形態[47]等方面鮮有變化。能繁母豬群感染PPV後，通常只表現出繁殖障礙：返情、窩仔數減少、木乃伊胎數量增加[69]。被PPV汙染的精液，在造成繁殖障礙時所起的作用，尚未明確。
Porcine parvovirus (PPV) is a small nonenveloped DNA virus that belongs to the family parvoviridae, genus Parvovirus. The virus is ubiquitous in the pig population. The main transmission routes of PPV are oronasal and transplacental. The virus has been isolated many times from semen of naturally infected boars. Boars can shed the virus in semen during the acute phase of infection [34]; shedding beyond this phase has not been demonstrated, but the possibility of immunotolerant carriers of PPV as a result of early in utero infection has been suggested [68]. Semen may also become contaminated by fecal particles containing virus, or within the male reproductive tract organs [45,46]. In boars, usually no clinical signs after infection are observed. On experimental infection in boars, no alternations in fertility or libido [46] or in sperm output, ejaculate volume, motility, or morphologic defects [47] were found. In breeding females, the major and often only clinical sign of PPV infection is reproductive failure: return to estrus, fewer pigs per litter, and increased numbers of mummified fetuses [69]. The role of semen contaminated with PPV in creating clinical reproductive problems has not been clearly established.
近期，在13份精液樣本[70]中的5份(38.5%)中檢到一種新型細小病毒，即PPV4，該病毒屬於細小病毒科、博卡病毒屬，且在Csagola等人[71]的研究中，一半的精液樣品也檢測到該病毒。尚不確定該病毒對豬群健康的影響。在匈牙利不同的豬群中，發現有其他新型豬細小病毒(PPV2, PPV3，豬細小病毒1和2，其他標記6V、7V的豬博卡病毒，豬類博卡病毒)，但無法在精液中檢測到[71]。
Recently, a novel parvovirus namely PPV4, belonging to the family parvoviridae, genus Bocavirus, was detected in 5 out of 13 (38.5%) semen samples [70], and in one out of two semen samples in a study by Cságola et al. [71]. The role of this virus in swine health has not been determined. Other novel porcine parvoviruses (PPV2, PPV3, porcine bocaviruses 1 and 2, other porcine bocaviruses labeled 6V and 7V, porcine boca-like virus) were found in pigs from different herds in Hungary, but they could not be detected in semen [71].